Hiba El Arja

Emmanuel Bourgeois

Sébastien Burlon

EFFET DU CHOIX DE LA LOI D'ECROUISSAGE SUR L'ESTIMATION DES TASSEMENTS INDUITS PAR DES EXCAVATIONS PROFONDES INFLUENCE OF THE HARDENING MODEL ON THE ESTIMATION OF SOIL SETTLEMENTS INDUCED BY DEEP EXCAVATIONS

Les tassements induits derrière le soutènement d'une excavation profonde dépendent des déformations plastiques du sol. On étudie deux modèles élastoplastiques, qui présentent respectivement une loi d'écrouissage isotrope et une loi d'écrouissage cinématique non-linéaire. Les deux modèles permettent d'obtenir des tassements (et non pas des soulèvements) derrière l'écran.

ABSTRACT -

The settlements induced behind the retaining wall by a deep excavation are linked to significant plastic deformations. In this article, two elastoplastic models are studied. They respectively present an isotropic hardening and a nonlinear kinematic hardening. Both constitutive models provide settlements (not heave) behind the retaining wall.

Introduction

En zone urbaine, les déplacements induits par la construction d'un écran de soutènement, en particulier les tassements, peuvent entraîner des désordres dans les ouvrages voisins. Les modélisations numériques sont le principal moyen d'évaluer ces déplacements. Les résultats des simulations dépendent beaucoup des modèles de comportement utilisés, et de leur aptitude à représenter les mécanismes de déformation du sol près de l'excavation.

Les modèles élastoplastiques combinent une partie élastique avec une partie plastique, définie par un critère, une loi d'écoulement et éventuellement une loi d'écrouissage. On discute ici l'importance de la partie plastique du modèle et notamment du type d'écrouissage. On étudie deux modèles : dans le premier, l'écrouissage est isotrope, il est défini par une homothétie centrée sur l'origine de l'espace des contraintes ; le deuxième modèle propose un écrouissage cinématique non linéaire. Dans les deux modèles, la loi d'écoulement est non associée.

On présente les formulations des modèles, puis on modélise un projet d'excavation réel. La comparaison avec le Hardening Soil Model [START_REF] Schanz | The hardening soil model: Formulation and verification[END_REF] montre que le premier modèle permet d'obtenir une estimation réaliste des déplacements horizontaux et verticaux induits par les phases de l'excavation. Le deuxième modèle, plus complexe, donne des tassements et des déplacements horizontaux plus grands.

Formulation du modèle H1

Le modèle H1 est basé sur le modèle MODSOL [START_REF] Chehade | Méthodologie pour la validation des modèles des géomatériaux-Application aux modèles élastoplastiques[END_REF][START_REF] Shahrour | Development of a constitutive elastoplastic model for soils[END_REF][START_REF] Azar | Problemes de sols satures sous chargement dynamique: modèle cyclique pour les sols et validation sur des essais en centrifugeuse[END_REF][START_REF] Zaher | Validation des modèles de sols sur ouvrages types[END_REF][START_REF] Shahrour | Numerical analysis of the behavior of piles in saturated soils under seismic loading[END_REF][START_REF] Khoshnoudian | Numerical Analysis of the Seismic Behavior of Tunnels Constructed in Liquefiable Soils[END_REF] développé pour modéliser le comportement des sables sous chargement monotone. Il combine une loi d'écrouissage spécifique et une règle d'écoulement qui permet de contrôler les déformations volumiques plastiques.

Partie élastique

Pour concentrer la discussion sur l'effet de la partie plastique du modèle sur l'estimation des déplacements, on se limite à une élasticité linéaire isotrope.

Critère de plasticité

Le critère du modèle H1 est un critère de Mohr-Coulomb «arrondi» : (2)

Loi d'écrouissage isotrope

La valeur actuelle de la variable R dépend de la déformation déviatorique plastique . Lorsque la déformation plastique devient grande, R tend vers la valeur R f qui donne la position limite de la surface de charge. Le paramètre b gère la vitesse à laquelle R se rapproche de sa valeur ultime :

avec (3)

Loi d'écoulement

L'incrément des déformations plastiques est divisé en incréments de déformations déviatoriques et de déformations volumiques plastiques :

. La loi d'écoulement se formule comme suit :

(4) où est le multiplicateur plastique. Les fonctions et qui définissent la direction des incréments volumiques et des incréments déviatoriques plastiques sont données par :

(5)

avec ( 6
)
Dans l'expression (5), le paramètre permet de faire tendre les déformations volumiques plastiques vers zéro pour des grandes déformations déviatoriques. Le modèle introduit également un angle caractéristique . Après l'entrée dans le domaine plastique, on peut avoir un comportement contractant tant que < ( + ) puis un comportement dilatant quand > ( + ). La loi d'écoulement vise à obtenir des tassements derrière l'écran lors de la modélisation d'une excavation. L'idée est de limiter le soulèvement du sol en considérant que le sol est contractant avant d'atteindre l'état caractéristique : les déformations volumiques plastiques compensent ainsi les augmentations de volume élastique.

Formulation du modèle H2

Le modèle H2 est basé sur la généralisation du modèle MODSOL aux chargements non monotones [START_REF] Chehade | Méthodologie pour la validation des modèles des géomatériaux-Application aux modèles élastoplastiques[END_REF][START_REF] Shahrour | Development of a constitutive elastoplastic model for soils[END_REF][START_REF] Azar | Problemes de sols satures sous chargement dynamique: modèle cyclique pour les sols et validation sur des essais en centrifugeuse[END_REF][START_REF] Zaher | Validation des modèles de sols sur ouvrages types[END_REF][START_REF] Shahrour | Numerical analysis of the behavior of piles in saturated soils under seismic loading[END_REF][START_REF] Khoshnoudian | Numerical Analysis of the Seismic Behavior of Tunnels Constructed in Liquefiable Soils[END_REF]. La formulation d'origine combine les deux types d'écrouissage isotrope et cinématique. Cet article vise plutôt à étudier séparément l'effet de chaque type d'écrouissage. On cherche à vérifier si un écrouissage cinématique rend compte d'une rigidité apparente supérieure, pour un chemin de contrainte en extension, à la rigidité apparente pour un chemin de contrainte en compression (dans le cas où K 0 < 1), et peut influencer les déplacements horizontaux et verticaux induits par les excavations. Comme dans le modèle H1, on adopte une loi élastique linéaire et isotrope.

Critère de plasticité

Dans le modèle H1, l'axe de la surface de charge coïncide avec la diagonale de l'espace des contraintes. Pour le modèle H2, une nouvelle quantité tensorielle notée est introduite pour définir la direction de l'axe de la surface de charge. La direction initiale de l'axe de la surface est définie à partir de l'état des contraintes initial :

(7)

Pour un état de contraintes initial isotrope, l'axe de la surface coïncide avec l'axe des contraintes isotropes. La surface de charge est définie en fonction d'un paramètre R 0 et de deux composants des contraintes notés et :

avec (8)
Les composants et généralisent la contrainte moyenne et le déviateur dans le cas d'une surface de charge dont l'axe n'est plus l'axe des contraintes isotropes. On les appelle respectivement contrainte moyenne locale et déviateur local. Ils sont définis par rapport à l'axe local de la surface de charge A ij . La contrainte moyenne locale correspond au tiers de la projection de l'état de contraintes sur l'axe de la surface de charge. Le déviateur local est alors relatif à la distance entre l'état de contrainte actuel et l'axe de la surface de charge. Ils sont donnés par :

où (9)
Dans le modèle H2, l'évolution de la surface de charge correspond à la rotation de son axe , qui correspond à un écrouissage cinématique non linéaire. est constant.

Loi d'écrouissage

La loi d'évolution du tenseur définit l'écrouissage cinématique de la surface de charge. Elle est basée sur celle donnée par [START_REF] Ghaboussi | Modelling and Analysis of Cyclic Behaviour of Sands[END_REF] Le taux de variation du tenseur est dirigé le long du tenseur déviatorique . Le paramètre contrôle la vitesse de rotation de l'axe de la surface de charge. Le terme permet de considérer la distance entre l'état de contraintes actuel et la surface de charge limite introduite implicitement dans le paramètre F. Comme dans le modèle H1, les paramètres R f et p c définissent le critère de rupture. Le paramètre E fait dépendre la rigidité du chemin de contraintes. Il dépend de la direction des tenseurs et :

;

(12)

Loi d'écoulement

Pour la loi d'écoulement, on adopte la même formulation que pour le modèle H1, dans un repère lié à l'axe de la surface de charge cinématique :

(13) (14)
Les deux modèles H1 et H2 ont été programmés dans une version « recherche » du code de calcul par éléments finis CESAR.

Application à une excavation dans les sables de Berlin

L'application choisie correspond à un projet d'excavation dans les sables de Berlin, qui a fait l'objet d'un concours de prévision [START_REF] Schweiger | Benchmarking in Geotechnics[END_REF]. Une analyse numérique avec différents types de modèles de comportement a été publiée. Elle montre que le modèle HSM constitue une bonne approximation de la réalité et peut être utilisé comme base de comparaison. Dans cette communication, on prend comme référence la version du modèle HSM implantée dans le logiciel CESAR. Cette version ne prend pas en compte le mécanisme volumique du modèle HSM de Plaxis ; elle donne des résultats en bon accord avec ceux obtenus avec Plaxis pour cet exemple.

Géométrie, phasage, conditions aux limites et maillage

L'exercice consiste à modéliser, en déformations planes, une excavation de 16,8 m de profondeur en quatre phases. Les conditions aux limites bloquent les deux composantes du déplacement au niveau du substratum et le déplacement horizontal sur les frontières verticales.

La paroi est soutenue par trois niveaux de tirants précontraints. Le calcul est divisé en 13 phases de calcul : initialisation des contraintes géostatiques (K o =1-sin ), activation de la paroi avec la méthode WIP (wished in place), une succession de 4 séquences comportant chacune une phase de rabattement de la nappe, une phase d'excavation et une phase d'activation d'un niveau de tirants (absente de la quatrième séquence). Le maillage comporte environ 5500 éléments quadratiques et 11000 noeuds.

Modèles

La hauteur totale de la paroi est de 32 m et elle fait 80 cm d'épaisseur. Son poids volumique est de 24 kN/m 3 et son comportement est élastique linéaire (E=30 000 MPa,  = 0,15). Elle est modélisée par des éléments de poutre.

Les tirants sont modélisés par des éléments de barre ; on distingue une partie libre et une partie scellée. Le module des tirants est égal à 210 000 MPa ; l'aire de la section pour la partie libre est égale à 5,94 cm 2 /m pour le premier niveau et 11,35 cm 2 /m pour les deux autres niveaux ; l'aire de la section pour la partie scellée est égale à 23,4 cm 2 /m pour le premier niveau et 40 cm 2 /m pour les deux autres niveaux. Les efforts de précontrainte sont égaux à 334, 700 et 726 kN/m pour les niveaux 1, 2 et 3.

L'interface entre le sol et la paroi est modélisée par des éléments sans épaisseur appelés 'éléments joints' ; leur module est pris égal à 100 fois la valeur du module E ur,ref du sol. L'angle de dilatance est nul pour ces éléments. On adopte pour l'interface des caractéristiques de résistance réduites par rapport à celles du sol :

; (15)
Pour le terrain, on distingue trois couches de sables en fonction de la profondeur. Un bouchon hydraulique imperméable est placé en pied de paroi. Il présente les mêmes caractéristiques mécaniques que le sol, et ne joue donc pas de rôle de butonnage. Le tableau 1 présente les paramètres du modèle HSM utilisés pour chaque couche. Pour le modèle H1, le module d'Young est calculé en fonction de la profondeur :

(16) où désigne la partie positive du réel : . Dans la formule ( 16), z représente la coordonnée suivant la verticale ascendante ; h est l'altitude de la surface de la couche considérée. Ses valeurs dépendent de l'origine des coordonnées verticales. vaut si z est inférieur à h, et au-dessus du plan d'altitude h. Comme on ne dispose pas de résultats d'essais en laboratoire, on détermine les paramètres du modèle H1 de la manière suivante : le coefficient de Poisson est pris égal au coefficient du modèle HSM. Les paramètres , k et n sont calculés de façon que le module donné par ( 16) soit égal à la valeur du paramètre du modèle HSM en haut, en bas et au milieu de chaque couche. La valeur du paramètre choisie, qu'on note R min, correspond à une surface de charge initialisée de manière que l'état initial est sur la frontière du domaine élastique au niveau de chaque point de Gauss. Pour les paramètres lt et lt, on retient les mêmes valeurs que pour le modèle HSM. Pour les autres paramètres du modèle H1, c, et b, on a modélisé des essais triaxiaux drainés avec le modèle HSM, pour les points situés à mi-profondeur de chaque couche avec les paramètres de la solution de référence, et on cale les paramètres du modèle H1 pour obtenir une réponse aussi proche que possible de celle obtenue avec le HSM. Pour mieux voir l'effet du comportement contractant sur les déplacements, on n'a pas retenu la valeur de b issue de ce calage mais adopté une valeur unique pour les trois couches b=0,015. Pour le modèle H2, les mêmes paramètres sont utilisés à l'exception des paramètres , et . On a choisi une valeur du paramètre faible pour que le sol se plastifie rapidement. Comme avec le modèle H1, l'angle est calé sur la courbe déformation axiale-déformation volumique des essais triaxiaux. Comme le paramètre b, la valeur de  est ajustée de manière que l'effet du comportement contractant sur les déplacements soit visible : on prend pour toutes les couches  =15000. Le tableau 2 présente les paramètres des modèles H1 et H2 utilisés. La figure 3 montre que les déplacements horizontaux calculés avec le modèle H1 sont presque les mêmes que les déplacements obtenus avec le modèle HSM. Des déplacements plus élevés sont obtenus avec le modèle H2.

E o (MPa) k (MPa) n (-)  (-) R o H1 (-) R o H2 (-)  c H1 (deg)  c H2 (deg)  (-)
Dans le concours de prévision, les mesures des déplacements horizontaux de la première et la dernière phase d'excavation seulement sont présentées. On peut noter que les deux modèles HSM et H1 sous-estiment les déplacements horizontaux par rapport aux mesures pour la première phase. Le modèle H2 donne des déplacements plus proches. Une meilleure estimation des mesures est observée pour la dernière phase notamment avec le modèle H1. Pour les moments fléchissants (non présentés ici), les trois modèles donnent des résultats très proches.

On peut aussi noter que la valeur maximale du déplacement horizontal u max obtenue avec le modèle H1, pour la dernière phase, vaut 0.18% de la hauteur libre de l'excavation H e . Le tassement maximal pour cette phase vaut 56%u max . La cuvette de tassement s'étend jusqu'à une distance égale à 3.5H e . Le tassement maximal est observé à une distance proche de 0.5H e . Ces valeurs sont en bon accord avec celles proposées par plusieurs auteurs à partir des méthodes empiriques [START_REF] Clough | Construction induced movements of in situ walls[END_REF][START_REF] Hsieh | Shape of ground surface settlement profiles caused by excavation[END_REF][START_REF] Moormann | Analysis of Wall and Ground Movements Due to Deep Excavations in Soft Soil Based on a New Worldwide Database[END_REF][START_REF] Ou | A simplified method for predicting ground settlement profiles induced by excavation in soft clay[END_REF][START_REF] Peck | Deep excavations and tunnelling in soft ground[END_REF].

Conclusions et perspectives

Cette communication porte sur l'effet de la partie plastique du modèle de comportement du sol sur l'estimation des déplacements induits par les excavations profondes. On compare les modélisations aux résultats du concours de prévision.

La comparaison des déplacements obtenus avec les modèles H1 et HSM est encourageante. La loi d'écoulement proposée permet de générer un comportement contractant qui produit des tassements derrière l'écran. La modélisation de l'interface solécran a une influence importante sur les tassements juste au contact de l'écran.

L'écrouissage cinématique non linéaire proposé pour le modèle H2 donne des tassements et des déplacements horizontaux plus grands que le modèle H1. La variation de rigidité selon les chemins de contraintes introduit dans l'écrouissage cinématique non linéaire n'a qu'un effet limité sur les soulèvements au niveau du fond de fouille. Ces déplacements sont gérés principalement par la partie élastique du modèle de comportement.

Dans le cadre du Projet Grand Paris Express, de nouvelles lignes de métro sont en cours de réalisation. La fouille de la future gare de Créteil L'Échat de la ligne 15 sud est choisie aussi comme cas d'étude avec le modèle H1. Les résultats numériques obtenus sont confrontés à des mesures réalisées dans cette gare pour plusieurs phases d'excavations. Les résultats montrent un bon accord avec les mesures. Ils sont présentés dans El Arja (2020).

Figure 1 .

 1 Figure 1. Déplacements verticaux du sol derrière la paroi pour les quatre phases d'excavation

  La figure 1 montre les déplacements verticaux derrière l'écran, pour les quatre phases d'excavation, avec les trois modèles HSM, H1 et H2. Le modèle H1 donne une cuvette de tassement derrière l'écran à partir de la 2 ème phase d'excavation et des tassements plus grands que le modèle HSM. Le modèle H2 donne des tassements plus grands dès la 1 ère phase d'excavation. Par ailleurs, la comparaison des tassements du modèle H1 avec les résultats présentés dans El Arja et al. (2019) montre que la modélisation de l'interface solécran a un effet considérable sur les tassements au voisinage de la paroi.La figure 2 représente les déplacements verticaux au fond de fouille. Pour les quatre phases d'excavation, les trois modèles donnent des résultats proches. Le modèle H2 améliore légèrement les soulèvements irréalistes observés au contact de la paroi par les modèles H1 et HSM où le sol est fortement plastifié.

	Sable 1	0-20	18	34	0,5	0,2	R min	0,15	29	43	10
	Sable 2	20-40	280	8	0,9	0,2	R min	0,15	32	50	10
	Sable 3	>40	413	8	0,9	0,2	R min	0,15	33	50	10
	4.3. Résultats


Youssef Atoini

Sotaro Kusumoto

Yoshihiro Koide

Shinya Hayami

Yang Kim
email: ykim@kumamoto-u.ac.jp

Jack Harrowfield
email: harrowfield@unistra.fr

Pierre Thuéry
email: pierre.thuery@cea.fr

,1ʹ-Dimethyl-4,4ʹ-bipyridinium as a multivalent structuredirecting counterion to anionic uranyl ion polycarboxylate complexes

Keywords: Uranyl ion, 1, 1ʹ-Dimethyl-4, 4ʹ-bipyridinium, Metalorganic networks, Structure elucidation

come

Introduction

The affinity of uranyl ion for carboxylate donor ligands has led to the existence of a large number of anionic complexes, many, though not all, containing the [UO2(O2CR)3] -entity, both in isolation or as a unit in a polymer [1][2][3]. In their crystalline state [2][3][4], such complexes must be directly associated with a countercation and in the case of uranyl ion coordination polymers and oligomers, there is extensive evidence that the nature of this countercation can have a major influence on the structure adopted by the anion, defining various prospects for applications of these materials [5][6][7][8][9][10]. While incorporation of a countercation into the actual uranyl polymer chain is a case where a major influence is to be expected, many other instances where the countercation is simply coordinated as a decorative unit on the polymer chain or where it is formally an independent species are more complicated to interpret. The range of cations that might be employed is immense but of the large number that have been investigated, only a single study concerns the simple quaternized aza-aromatic, 1,1ʹ-dimethyl-4,4ʹ-bipyridinium (Me2bipy 2+ , "paraquat" or "methyl viologen", Scheme 1) [11], and it is outnumbered by studies where protonated aza-aromatics have been employed and where their structural influence appears to involve their NH-bond donor activity [12][13][14][15][16][17][18][19], a role unavailable to their quaternized derivatives. Viologens functionalized with metal ion binding groups have been more extensively studied [20,21], but in these cases the quaternary centre is covalently attached to the coordination polymer. In the present work, extension of the use of Me2bipy 2+ as a countercation to anionic uranyl ion complexes of previously well-studied polycarboxylate ligands has provided evidence of the peculiar behaviour of this cation. The polycarboxylic acids used cover a wide range of geometry and flexibility, including phthalic (H2pht), citric (H4cit), (2R*,3R*,4S*,5S*)-tetrahydrofurantetracarboxylic (H4thftc), 2,5-thiophenedicarboxylic (H2tdc) and pimelic (H2pim) acids (Scheme 1). The first cases of Me2bipy 2+ incorporation as a counterion in this study were obtained when using the zwitterionic dicarboxylate 4,4ʹ-bis(carboxylatomethyl)-4,4ʹ-bipyridinium (bcmbp) which underwent degradation into Me2bipy 2+ under the conditions used, in contrast to the 4,4ʹ-bis(2-carboxylatoethyl)-4,4ʹbipyridinium congener, which has been successfully used as a coligand in uranyl ion complexes [22,23], while other cases were synthesized using Me2bipyCl2. The resulting seven complexes have been characterized by their crystal structure and, where possible, their emission spectrum in the solid state. While the room temperature crystal structure of the complex involving 2,5thiophenedicarboxylate has previously been reported [11], we present here the low temperature structure for the sake of discussion.

Scheme 1. The zwitterionic carboxylate bcmbp, Me2bipy 2+ dication, and carboxylic acids used.

Experimental section

Synthesis

Caution! Uranium is a radioactive and chemically toxic element, and uranium-containing samples must be handled with suitable care and protection. Small quantities of reagents and solvents were employed to minimize any potential hazards arising both from the presence of uranium and the use of pressurized vessels for the syntheses.

Dioxouranium(VI) nitrate hexahydrate, [UO2(NO3)2(H2O)2]•4H2O (RP Normapur, 99%)
was purchased from Prolabo. 1,1ʹ-Dimethyl-4,4ʹ-bipyridinium dichloride (Me2bipyCl2), phthalic acid (H2pht), (2R*,3R*,4S*,5S*)-tetrahydrofurantetracarboxylic acid (H4thftc), 2,5thiophenedicarboxylic acid (H2tdc) and pimelic acid (H2pim) were from Aldrich, and citric acid (H4cit) was from Fluka. 4,4ʹ-Bis(hydroxycarbonylmethyl)-4,4ʹ-bipyridinium dibromide (bcmbpH2Br2) was prepared by a slight modification of the previously reported method [24].

For all syntheses, the mixtures in demineralized water/organic cosolvent were placed in 10 mL tightly closed glass vessels and heated at 140 °C in a sand bath, under autogenous pressure. The crystals characterized were those deposited under the reaction conditions and not from subsequent cooling and depressurization.

2.1.1. [Me2bipy]2[(UO2)4(pht)4(O)2] (1)
H2pht (9 mg, 0.05 mmol), [UO2(NO3)2(H2O)2]•4H2O (25 mg, 0.05 mmol), and bcmbpH2Br2 (22 mg, 0.05 mmol) were dissolved in a mixture of water (0.6 mL) and N,Ndimethylacetamide (DMA, 0.2 mL). A few yellow crystals of complex 1 were obtained within two weeks.

Crystallography

The data were collected at 100(2) K on a Bruker D8 Quest diffractometer equipped with an Incoatec Microfocus Source (IS 3.0 Mo) and a PHOTON III area detector, and operated through the APEX3 software [25]. The data were processed with SAINT [START_REF]SAINT, ver. 8.40A[END_REF], and absorption effects were corrected for empirically with SADABS [START_REF]SADABS, ver[END_REF]. The structures were solved by intrinsic phasing with SHELXT [28] and refined by full-matrix least-squares on F 2 with SHELXL, using the ShelXle interface [29]. All non-hydrogen atoms were refined with anisotropic displacement parameters. The hydrogen atoms bound to oxygen atoms in complexes 2, 3 and 4 were found on residual electron density maps and they were either refined with restraints or treated as riding atoms. All other hydrogen atoms were introduced at calculated positions and were treated as riding atoms with an isotropic displacement parameter equal to 1.2 times that of the parent atom (1.5 for CH3). In 3, one uncomplexed carboxylic group is disordered over two positions which were refined with occupancy parameters constrained to sum to unity and with restraints on bond lengths and displacement parameters. In complex 7, the carbon chains of two pimelate ligands are partially disordered and the different positions have been refined with occupancy parameters constrained to sum to unity and with restraints on bond lengths, angles and displacement parameters. Voids in the structures of 1, 2 and 6 are probably occupied by very disordered and unresolved solvent molecules, and the SQUEEZE software [30] was used to subtract the contribution of these solvent molecules to the structure factors. Complex 2 crystallizes in the space group P1 as an inversion twin with a Flack parameter of 0.239(3); the a and b unit cell parameters of 2 are accidentally equal to one another, and the  and  angles close to each other, but no solution with a higher symmetry was found.

Crystal data and structure refinement parameters are given in Table 1. Drawings were made with ORTEP-3 [31] and VESTA [32], and topological analyses were performed with ToposPro [33].

Table 1 Crystal data and structure refinement details.

Luminescence measurements

Emission spectra were recorded on solid samples using an Edinburgh Instruments FS5

spectrofluorimeter equipped with a 150 W CW ozone-free xenon arc lamp, dual-grating excitation and emission monochromators (2.1 nm/mm dispersion; 1200 grooves/mm) and an R928P photomultiplier detector. The powdered compounds were pressed to the wall of a quartz tube, and the measurements were performed using the right-angle mode in the SC-05 cassette.

An excitation wavelength of 420 nm was used in all cases and the emission was monitored between 450 and 600 nm. The quantum yield measurements were performed by using a

Hamamatsu Quantaurus C11347 absolute photoluminescence quantum yield spectrometer and exciting the samples between 300 and 400 nm.

Results and discussion

Crystal structures

A dicarboxylate ligand which alone has generated a considerable volume of uranyl ion coordination chemistry is phthalate [34][35][36][37][38][39][40][41][42][43][44]. Amongst the quite varied complex ion species identified, a small oligomer in which four U VI centres, two in pentagonal-bipyramidal and two in hexagonal-bipyramidal coordination, linked by triply-bridging oxide ions has been commonly encountered [34,35,43,44]. This same species is present in The last interactions can be considered as an initial step of nucleophilic addition to an activated at their junction (Fig. 3d). When viewed down [110], the packing defines channels occupied by the counterions, with small solvent-accessible voids being present (KPI, 0.68). As in complex 1, there is a significant twist of each of the two inequivalent Me2bipy 2+ units [dihedral angle for that involving N1 and N2, 18.1(3)°, for that involving N3 and N4, 26.8(3)°], with both having the same chirality, whereas in complex 1 the unique cation is present as both enantiomers.

Parallel-displaced -stacking interactions involving pht 9) Å] (Fig. 4). This results in formation of dimeric units {[UO2(Hcit)]2} 2- which are doubly connected to one another to form a monoperiodic polymer of a well-known form [54], here directed along [ Another ligand widely exploited in uranyl ion coordination chemistry is the dianion derived from 2,5-thiophenedicarboxylic acid (H2tdc) [11,15,46,[59][60][61][62][63][64][65][66]. The crystal structure of the complex {[Me2bipy][(UO2)2(tdc)3]}n (5) has previously been determined at room temperature [11], and we report only briefly here the structure determined at 100 K for the sake of discussion of weak interactions. The unique uranium atom is here tris( 2 O,O'-chelated) by three tdc 2-ligands to form the common diperiodic polymer with hcb topology [U-O(oxo), 1.7680(10) and 1.7771(10) Å; U-O(carboxylato), 2.4441(10)-2.5202(9) Å] (Fig. 6). In addition to the usual CH•••O interactions, the HS (Fig. 2) does indicate the centrosymmetric cation to be involved in two weak interactions with thiophene sulfur atoms, generally observed in other known structures not to be involved in any interaction beyond dispersion. These interactions involve only one of the two inequivalent tdc Aliphatic dicarboxylic acids are another well-studied source of uranyl ion ligands [12,[67][68][69][70][71][72], with the C7 species, pimelic acid (H2pim), commonly encountered. The complex {[Me2bipy][(UO2)2(pim)3]}n (6) has the stoichiometry suited to the provision of three carboxylate units for each uranyl but it is known [67] that this does not guarantee the formation of a simple honeycomb diperiodic array, even when hexagonal-bipyramidal coordination of the U VI centres is achieved, and in fact the length and flexibility of pimelate appear to enable its complexes to adopt a variety of more complicated forms. In the present case, the unique uranium atom is tris( 2 O,O'-chelated) by three pim 2-ligands [U-O(oxo), 1.783(8) and 1.790 (9) Å; U-O(carboxylato), 2.443(8)-2.499( 9) Å], and it is thus a 3-c node (Fig. 7). The diperiodic network formed, parallel to (001), is however not the common hcb, but it has the {8 2 .10} point symbol and the KIa topological type, previously found in several uranyl ion complexes with elongated ligands [12,46,70,73]. The layers are sufficiently thick (⁓8. possibly present in some of the complexes only, particularly 1, 2 and 4, with formation of columns of counterions in the last case. In most compounds, interactions between carboxylate groups or uranyl oxo atoms and the aromatic system are discerned from the HSs (Fig. 2). In complexes 1 and 2, they seem to involve more particularly N + , which is close to an oxo group, while in complexes 3 and 5-7, they involve carbon atoms located preferentially in ortho or meta positions with respect to nitrogen, possibly because these are sites susceptible to nucleophilic attack due to polarization of the pyridinium ring by N + (Scheme 2). It may be noted that interactions of oxo groups with the aromatic rings in the present series occur only in the case of pentagonal-bipyramidal uranium cations in complexes 1-3, and this is true also for hydrogen bonds formed by the terminal methyl groups in 5 and 7. These apparent distinctions in the interactions of the cation with uranyl ions having different coordination numbers may simply be a steric effect favoring the less hindered oxo groups in the pentagonal-bipyramidal species, as U=O bond lengths do not provide convincing evidence of a possible difference in basicity.

Scheme 2. Electron distribution within a pyridinium ring.

Luminescence

Emission spectra in the solid state under excitation at 420 nm were measured for complexes 2, 3 and 4. Complex 1 was not obtained in sufficient quantity, complexes 6 and 7 were only synthesized as a mixture, and complex 5 is non-emissive (while the previous report gave a very broad and extremely weak emission [11]), behaviour which is relatively common with complexes of the tdc 2-ligand [62]. Complex 2 is the most emissive, with a photoluminescence quantum yield (PLQY) of 17%, while 3 and 4 have much smaller PLQYs of <1% and ⁓2%, respectively. The three spectra, shown in Fig. 9, show the typical vibronic progression due to the S11  S00 and S10  S0 ( = 0-4) transitions of the uranyl ion [74,75]. The four most intense peaks are located at 489, 511, 534 and 559 nm for 2, 506, 527, 551 and 578 nm for 3, and 496, 518, 542 and 569 nm for 4. Uranium centres are in pentagonal-bipyramidal environments in all three complexes, and the maxima positions span the usual range for uranyl ion complexes with O5 equatorial environments [76]. The shifts between the three spectra may be related to the slight differences in the nature of equatorial donors, five carboxylate or four carboxylate and one water oxygen atoms in 2, three carboxylate and two alkoxide groups in 3, and four carboxylate and one ether group in 4. Bond valence parameters [77] calculated with PLATON [45] are consistent with this result for complexes 2 and 3 since the sums of the two bond valences for the axial donors are 3.393 and 3.183, respectively, the corresponding variation in bond strength inducing a redshift in the latter case, but not quite for 4, in which the sum is 3.684.

[Me2bipy] 2 [

 2 (UO2)4(pht)4(O)2] (1), shown in Fig. 1. The tetranuclear assembly is centrosymmetric, and the U-O bond lengths are unexceptional [U-O(oxo), 1.7833(13)-1.7953(13) Å; U-O(carboxylato), 2.5543(15)-2.6079(14) Å for the  2 O,O'-chelating groups, 2.3279(13)-2.4325(13) Å for the others; U-O(oxido), 2.2154(13)-2.2506(12) Å]. When viewed down [001], the packing displays a herringbone arrangement of tetranuclear units, with small solvent-accessible voids being present (see Experimental section), as shown by the Kitaigorodski packing index (KPI, evaluated with PLATON [45]) of 0.70. Analysis of short contacts with PLATON indicates the possible presence of two significant parallel-displaced stacking interactions involving both pht 2-ligands and the ring of the counterion containing N2 [centroidcentroid distances, 3.5996(11) and 3.7568(11) Å; dihedral angles, 3.63(9) and 10.23(9)°; slippages, 1.09 and 1.41 Å], and also one CH••• interaction between one hydrogen atom of the ring containing N2 and one pht 2-ring [Hcentroid distance, 2.62 Å; C-Hcentroid angle, 164°]. More unusual, an interaction may involve the uranyl oxo atom O1 and the ring

Fig. 1 .

 1 Fig. 1. (a) View of complex 1 with displacement ellipsoids shown at the 50% probability level and hydrogen atoms omitted. Symmetry code: i = 1 -x, 1 -y, 1 -z. (b) View of the packing with uranium coordination polyhedra colored yellow.

Fig. 2 .

 2 Fig. 2. Hirshfeld surfaces mapped with dnorm of the Me2bipy 2+ cations in complexes 1-7 with indication of the principal weak interactions formed. Not all CH•••O lateral interactions are indicated for clarity. Only one HS of the two very similar counterions in 7 is shown.

Fig. 3 .

 3 Fig. 3. (a) View of compound 2 with displacement ellipsoids shown at the 50% probability level. The counterions and carbon-bound hydrogen atoms are omitted, and hydrogen bonds are shown as dashed lines. Symmetry codes: i = x, y -1, z -1; j = x, y + 1, z + 1. (b) View of the monoperiodic polymer. (c) Packing viewed along the channels direction. (d) Nodal representation of the polymer (uranium nodes, yellow; pht 2-nodes and edges, blue).

Fig. 4 .

 4 Fig. 4. (a) View of one of the two independent units in compound 3 with displacement ellipsoids shown at the 30% probability level. The counterion, solvent molecule and carbon-bound hydrogen atoms are omitted, and only one position of the disordered groups is represented. Symmetry codes: i = 1 -x, 1 -y, 1 -z; j = 2 -x, 1 -y, 1 -z; k = x -1, y, z. (b) View of the monoperiodic polymer. (c) Packing viewed down the chain axis, with hydrogen bonds shown as dashed lines.

Fig. 6

 6 Fig. 6 (a) View of compound 5 with displacement ellipsoids shown at the 50% probability level and hydrogen atoms omitted. Symmetry codes: i = 1/2 -x, y + 1/2, 1/2 -z; j = 1/2 -x, y -1/2, 1/2 -z; k = 1 -x, y, 3/2 -z; l = 1 -x, 1 -y, -z. (b) View of the diperiodic network and the counterions closer to the rings. (c) Packing with sheets viewed edge-on.

  5 Å) to completely encompass the counterions, which have 2-fold rotation symmetry and a dihedral angle of 20.9(2)° between the two rings. The large separation between the counterions precludes any stacking interaction, and the HS (Fig. 2) shows interactions of carboxylate oxygen atoms with carbon centers adjacent to N + only, in addition to the ubiquitous CH•••O hydrogen bonds. The KPI of 0.66 indicates the presence of solvent-accessible voids.

Fig. 7

 7 Fig. 7 (a) View of compound 6 with displacement ellipsoids shown at the 30% probability level and hydrogen atoms omitted. Symmetry codes: i = x -1/2, y + 1/2, z; j = x + 1/2, y -1/2, z; k = 1 -x, y, 3/2 -z. (b) View of the diperiodic network and the included counterions. (c) Packing with sheets viewed edge-on. (d) Nodal representation of the KIa network (uranium nodes, yellow; pim 2-edges, blue).

Fig. 8

 8 Fig. 8 (a) View of compound 7 with displacement ellipsoids shown at the 30% probability level and hydrogen atoms omitted. Only one position of the disordered parts is represented. Symmetry codes: i = -x, 3 -y, 2 -z; j =x -1, 2 -y, 1 -z; k = x, y -1, z -1; l = x -1, y, z; m = x, y + 1, z + 1; n = x + 1, y, z; o = 2 -x, 1 -y, 1 -z; p = 1 -x, 2 -y, 2 -z. (b) View of the diperiodic network. (c) Packing with sheets viewed edge-on. (d) Nodal representation of the network (uranium nodes, yellow; pim 2-nodes and edges, blue). (e) Interdigitation of two

Fig. 9

 9 Fig. 9 Emission spectra of complexes 2, 3 and 4 in the solid state, under excitation at 420 nm.

1 ,

 1 1ʹ-Dimethyl-4,4ʹ-bipyridinium as a multivalent structuredirecting counterion to anionic uranyl ion polycarboxylate complexes Youssef Atoini, Sotaro Kusumoto, Yoshihiro Koide, Shinya Hayami, Yang Kim, Jack Harrowfield, Pierre Thuéry 1,1ʹ-Dimethyl-4,4ʹ-bipyridinium ("paraquat") was used as a structure-directing counterion in the solvo-hydrothermal synthesis of seven uranyl ion complexes with polycarboxylates, resulting in some novel arrangements and allowing an analysis of the weak interactions involved.

  Table of Contents Entry

Conclusions

We have reported the synthesis and crystal structure of seven uranyl ion carboxylate complexes with Me2bipy 2+ as structure-directing counterion, as well as the luminescence properties for three of them. These structures involve polycarboxylates which have all been used previously in the presence of different additional reagents. The structures obtained here are only partly different in nature from those already known, since the discrete, tetranuclear complex 1 with phthalate displays a rather common geometry and coordination mode, and the monoperiodic polymer with citrate (3) as well as the diperiodic hcb network with 2,5thiophenedicarboxylate ( 5) are also well-known motifs. The other complexes show that Me2bipy 2+ can in some cases give rise to new forms of anionic uranyl ion coordination polymers as a result of interactions not seen with other known cations. However, with respect to other counterions which are strong hydrogen bond donors, such as NH4 + or Co(en)3 3+ (en = ethylenediamine), or which easily interact with one another such as PPh4 + through phenyl embrace, the interactions involving Me2bipy 2+ are multiple and weak and there is no obvious tendency to aggregate, somewhat limiting the structure-directing capacity of this cation.

Appendix A. Supplementary data CCDC 2306528-2306534 contain the supplementary crystallographic data for 1-7. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.


THE BLOODY HAND Blaise Cendrars

Maria Tudosescu

Vie De Cendrars

BETWEEN REAL AND FICTITIOUS TRENCHES

The memoir lies somewhere at the crossroads between literature and document, offering a look into a shared past, but a very subjective one for that matter, obeying the voice of one author, who cannot write without creating some form of literature. As such, it becomes a very interesting literary genre: free to play with perspectives and with the senses of the reader, borrowing literary devices from fictional works, it is still deeply anchored in real life. The current article focuses on Blaise Cendrars' experience on the battlefields of the First World War as depicted in his memoir The Bloody Hand. First a writer, then a soldier, Blaise Cendrars could not escape the artist's natural instinct to turn his life into art, inviting the reader into his chaotic, fragmented, dirty, nostalgic, cruel, at times unbelievable experiences in the trenches. In order to better understand this intricate process of reviving memories and turning that very process into literature, the article proposes a look at the writer's use of literary devices -humour, surrealist elements, irony, metaphor or foreshadowing-to recreate an authentic, yet highly aestheticised war narrative.

Frédéric Louis Sauser in Search of Purpose

Blaise Cendrars' biography reads, at times, more like a work of fiction than a true story: from his name to his journeys, to his stories, one can never be quite sure where the border of reality crosses

among other intellectuals who urge young men to join the army and fight for their country. Moreover, he even signs an open letter to those other foreigners who, like himself, had been adopted by France and would be suited to join the Foreign Legion: "On the 29th of July 1914, two days after the declaration of war, I signed together with Riccioto Canudo, […] an 'AppeI' which was published in all Parisian newspaper and which had a great impact." Thus, the Foreign Legion, patched up by soldiers from 2 different corners of the world, became a somewhat controversial part of the army.

On the one hand, it was one of the most successful French army forces during the Great War; on the other hand, more often than not, it seemed like "a chronicle of dropouts, of misfits, of refugees, of men commonly regarded as out of place in normal society." Their motives for 3 fighting were, consequently, just as diverse and while some joined out of sincere belief in the French cause and out of genuine love for their adoptive country, Blaise Cendrars states, in a reply written down in his memoir, that he only went to war because of his deep hatred for the Germans. Whatever the reason, it is nevertheless worth observing that, 4 unlike many other soldiers, he and the other men fighting in the Legion were there solely by choice, because they wanted to take part in the war; they were never called to arms, they reached out for them -and most of them quickly regretted the decision.

Writers in and of the Trenches

The poet who seemed determined to escape any limitations that reality would impose both in his life, by changing his name and therefore his identity, and in his writings, by innovatively combining symbolist, expressionist and Dada elements, was suddenly thrown into a real chaos of bold sounds and shocking images: the battlefield. Extremely destructive, the Great War was a failure of the modern spirit, a proof that progress always comes with a cost. Nevertheless, it must also be said that the experience of war greatly influenced the arts of the 20th century. Surely, the war motif had always been a source of inspiration for artists, long before 1914. However, what is particularly interesting, especially in the French army, is the emphasis that was suddenly put on witnesses' accounts. Cendrars and many other soldiers, some of which had no connection to literature whatsoever, were encouraged to write down their daily experiences and were even published in special newspapers: Blaise "It became another facet of a soldier's duty-culturally, morally, and aesthetically-to capture his experiences in written word. This conception of the soldier as writer took root in cultural antecedents from Third Republic educational reforms, which helped make French soldiers more receptive, indeed dedicated, to writing from the trenches. The trench newspapers embraced the concept, routinely encouraging soldiers to write their experience. This confluence of factors resulted in the creation of the term-écrivain-combattant-with particular resonance in the French context." [START_REF] Fass | The Memoir Problem in Reviews in American History[END_REF] All of a sudden, it wasn't just writers writing anymore; indeed, all those who took part in the battle were invited to express themselves. Which, of course, meant that an impressive number of accounts surged amidst one of the greatest conflicts in the history of mankind, providing intimate details about life in the gutter. Whether all of these can be considered literature is debatable. Nevertheless, they remain as testament to that unique experience, to be compared and even placed into dialogue with historical writing.

Blaise Cendrars was also among those who scribbled down his war experience since 1914, when he joined the Foreign Legion until September 1915, when he lost his right arm in battle. Reading his accounts, it seems as though the writer's main purpose was not so much the description of the fight itself or of the surroundings, but rather finding the little humanity that was left amidst all the death: Blaise Cendrars is particularly concerned with the people he encountered in his serving time, creating a gallery of bizarre portraits of strange men, almost comically accentuating their most prominent feature, similar to a Van Gogh painting. However, unlike those "writers of the trenches", the poet kept his entries private even long after the war was already over: the writer only published his war memoirs in 1945, after the end of the Second World War. But, if he took his time, it was with good reason and when he did decide to publish, his memoirs became a valuable source of information: between 1945 and 1949 he publishes no less than four war memoirs: The Astonished Man (L'Homme foudroyé, 1945), The Bloody Hand (La main coupée, 1946), Planus (Bourlinguer, 1948), and Sky (Le Lotissement du ciel, 1949). [START_REF] Harari Yuval | Renaissance Military Memoirs: War, History and Identity[END_REF] It seems as though Cendrars had to give himself some time to ponder over his life in the trenches before he could turn that intense and confusing experience into literature. In fact, he is the one who explains his delay in turning real life into literature: "You are either combatant or writer. When you write, you don't shoot with a rifle and when you shoot with a rifle you don't write, you write afterwards." For the French writer, 8 writing and fighting are two antithetic activities, which cannot be done simultaneously -or, at least, not well. War is felt, lived intensely, fought to the last breath and observed attentively; literature comes subsequently, when the senses calm down and the mind has time to make sense of the chaos: "On the battlefield, I was a soldier. I shot. I didn't write. I left that activity for my men, who never ceased to create, create, create, writing to their women." He clarifies this process of creation once again in his 9 memoir, as he is recalling a conversation with a policeman, who is surprised that a poet would not be more inspired by the war, which, in turn, he finds sublime and a subject worthy of poetry. In his reply, Cendrars sums up his own opinion on it: "The war is filth […] The dangerous life might be convenient to an individual, certainly, but on the social plan, it leads directly to tyranny […] . 10 Overwhelmed by its intensity, the writer needs the experience of war to settle inside himself, before he can transform it in words, before he can restore it authentically, through literature. During his experience, he 'stocks' information, sensations and emotions in his mind, but only time can transform all that raw emotion into coherent fragments of literature. Perhaps the reality of war itself resisted its transformation into art and, aware of his limitations in reproducing the war truthfully, the writer needed time to create his own path, build a voice that would suit this strange reality, especially if it should focus on the stories of his dead fellow soldiers: "The war zone as elegiac space is a construct of postwar record narratives. […] War itself, however, in its own time, has no time for elegy. The war zone is destructive of elegy, warping the time needed to mourn, forcing the mourner to put that impression away, to be pondered at a later time." [START_REF] Mcloughlin | War and Words in The Cambridge Companion to War Writing by Kate McLoughlin[END_REF] Unlike many other war memoirs of the Great War, which centre on the battles and follow a chronological plot, the four volumes of memoirs written by Cendrars remind the reader more of a collage than of a story, being "an indissoluble continuum of reminiscences of people, places, readings, personal adventures lives or dreamt about, cross references to previous writings, reflexive pauses on the nature of writing or the directions the world and man are taking today, spiritual meditations, all woven into an intricate web through the consciousness of the author." [START_REF] Palmer | Memories from the Frontline: Memoirs and Meanings of The Great War from Britain, France and Germany[END_REF] However, this artistic approach might be more useful in representing the reality of war than one might originally think -in order to represent such anexperience as authentically as possible, writers might need to resort to different types of texts, especially an artist as enamoured with the surreal and the absurd as Cendrars. In fact, in her study about the Great War and its representation, Virginie Renard comments on this very aspect: "It seems that novels that evoke the First World War [...] have to borrow from the technique of the collage and incorporate other types of texts, as if literary prose alone could not convey a satisfactory image of the conflict." For Cendrars, the classical chronology does not serve the 13 accuracy of war -it is too clean, too organised. Like the war itself, his memories are chaotic and scattered, a hodgepodge of battles and all the moments in between, centred on random, ordinary people, each with their own little universe of experiences. Spontaneously, following the course of each random memory that pops into his head, Cendrars writes as he remembers, simulating with his style the intricate workings of his memory.

The Bloody Hand

The book that I have chosen to focus on, The Bloody Hand, is the second part of the tetralogy of war memoirs, being the most elaborate and complex of the four. Published in 1946, the book is dedicated to Cendrars' two sons, Rémy and Odilon, who were both killed in the Second World War. The first page of the book is covered in random texts (notes, a letter, a postal card) about and respectively from his son, Rémy, without any commentary; they are simply displayed at the beginning of the story, as if through them, Cendrars would also include his own son in his chronicles of war. Additionally, before diving into the story, the writer quotes a highly disputed biblical passage from Jeremiah's book: "The Lord has created a new thing on earth: the woman shall compass the man." While he never reveals the meaning behind the chosen paragraph, 14 it could be assumed that it refers to the reversed order of a world thrown into chaos, in which all the old, traditional values are thrown upside down.

As for the form of the book, it could be considered a bizarre kind of homage to the people Cendrars would meet during his serving time, in which retellings of stories are written down along with war songs, while bits of poetry make their way into fragments that describe a battle. Already in the second chapter, for instance, as the soldiers are described during their march, a war song is written down lyric for lyric , letting the 15 reader emerge into a world composed not only of words but of senses, where sounds and smells become just as important as images. The only thing that keeps all these dissipate fragments together to ultimately create a coherent account of the war is the narrator himself, not only as narrator, but as an active participant in the story, switching between being subject or object of his own narration. This double role, both as participant and observer, is also what links Cendrars to the other soldier writers and what gives him authority to claim accuracy for his stories: "Accordingly, authority in twentieth-century memoirs is experiential rather than factual, and depends on 'voice' rather than eye-witnessing. It is assumed that anyone can know the facts, even if they were not there -indeed, eyewitnesses are not necessarily the best source for the facts. However, only those who experienced can know how it felt, and hence only they can speak with an authoritative voice." [START_REF] Savage | The Functions of War Literature in South Central Review[END_REF] As I have already pointed out, it is harder to find a storyline in Cendrars' memoir than it is in other war memoirs. However, a quick look at the titles of the chapters can provide an insightful clue. Often enough the titles are names of the people that Cendrars fought alongside: Rossi, Lang, Robert Bellesort, Goy and many others. Sometimes, these names are followed by an interesting piece of information: the place and cause of death of that particular character, as if the narrator would be creating funeral stones, at the feet of which he buries the stories of those who were lost. For example, before reading the chapter about Rossi, the reader is already made aware of the fact that he will be killed in Tillolo , or before 17 the story of Goy the reader finds out that he was made prisoner at La Croix and never found again . A question that arises then is whether 18 these people, these names that follow each other in the form of chapters, are just a pretext to write a personal story which can be easily hidden behind a stranger's name, or whether the whole process of writing these episodes is, in fact, a way of remembering those people and making them immortal -at least, in writing. Moreover, as one reads the unbelievably absurd stories that make up the reality of the author, one can't help but wonder how much of it all is the writer's embellishment (also considering the amount of time that passed between the events and the writing) and how much is the authentic, accurate experience.

For one, the memoir is undeniably about people: fellow soldiers who were lost in action, veterans, who remained scarred after the experience, the anonymous individuals who are no longer remembered for all they were: "The conflict is omnipresent in his [Blaise Cendrars'] work, but essentially he used the war events as a literary source for inspiration, as well as an original and inexhaustible way of telling stories about people." This could be envisioned as a cry of the French writer 19 against the impersonality of the war experience and its overgeneralisation, when soldiers go from being individuals to being just a number, a barely human entity, lost among others: "In honouring the dead, survivors testified to their exclusion from the war's ultimate meaning -sacrifice -except vicariously as witnesses. The role of the living is to offer tribute, not receive it." By singling them out from the 20 crowd and giving them their own space in his memories, as well as in his memoirs, Cendrars fulfils his mission as a war survivor and lends his fellow soldiers a voice and therefore, a sense of self, making the point that "people remain the fundamental unit of historical experience and power of this memoir, as well as the most undeniable proof of its accuracy, is indeed a certain resistance to create a universal story about the war and the insistence on the personal detail; the stories of his fellow soldiers come to define his own sense of self, just as their shared views on the war become mixed with his own: "I didn't want to generalise. I'm only talking about what I have seen and the horizon of the soldier is limited and does not surpass the limit of his squad, his section, his company." If the universe of the combatant is little, then all the more 22 powerful are the influences of that universe on his sense of self.

Je Becomes Nous

So, if Cendrars is exposing the stories of his comrades, it is also because through them he can make better sense of his own war experience. Sometimes, the mingling of the squad's memories is noticeable in certain episodes of the memoir as well, when a character's side of the story would complete the author's lacking information. For example, Garnéro's supposed death is told from two perspectives: one time, as Cendrars remembers it and another time, as Cendrars hears it from Garnéro himself, ten years after the war, when the two meet randomly on the streets of Paris and start reminiscing about their days as soldiers. 23 Another interesting example for the way the collective memory of the squad and the remembered events of its combatants mix together are the battles from d'Artois, in the spring of 1915, which play an important part in Cendrars' memoir, being mentioned already in the second chapter of The Bloody Hand. However, according to the research of Laurent Tatu and Julien Bogousslavsky, the French writer couldn't have participated in these legendary battles, as his regiment was stationed near the Somme at the time. Nevertheless, they play an important role for the regiment that he would join later on, in July 1915, as well as for some of his soldier friends, who did actually fight at d'Artois. Therefore, by repeatedly hearing about the legendary battles, he comes to integrate those memories into his own, remembering something that he has never actually experienced. This mingling of sensations and memories is also conveyed in the use of the plural pronoun "nous" (we) rather than the individual "je" (I) in some instances of the narrative, especially during a battle, when the experience becomes one shared by everyone involved:

"We were at the end of the line. It was happening. Our legs were as if cut off. Out of breath. Our hearts were beating in our throats. The hands were shaking. A flood of sweat ran down our spines. [...] We therefore squeezed in the furrows, happy and dismayed, huddled against each other." 25 By using people as his main pretext to write about the war experience, Cendrars manages to deliver a very personal image of the Great War -not as it was experienced back then, but as it remains in the mind of one particular combatant, thirty years after the conflict.

When Remembering Takes Time

In the eyes of the writer, the immediacy of writing does not necessarily assure the accuracy of the account: often the witness can be too focused on one aspect, too shocked to process the events and the story would result in random impressions that would be more descriptive of the sensation itself than on the overall image: "If I would have written The Bloody Hand immediately after the war, it would have been a different book, more made-up, photographed, instant, but not more veridical because of that. Synthesising needs a certain distance. Forgetting too. And forgiveness!" 26 Moreover, this distance between the writing and the written lifts off some of the accuracy claims that would weigh immediate war memoirs down. Readers of the twenties were more concerned with the practical details of the war they had just lived through, seeking to find in a combatant's memoir a purpose for the war, as well as a way of remembering it through facts: the figures, the battles, the strategies. But the readers of The Bloody Hand, who had just been through two world wars in the span of fifty years, were perhaps less focused on the accuracy of every single detail and more interested in the act of creation as such, perhaps as a way of rebuilding a world from which only ruins remained, through the eyes of those who experienced it first-hand: once history fails to give any reassurance or meaning to all that suffering, it leaves place for the art to pick up the shambles and reconstruct the past in a way that anyone could find some kind of consolation in it.

For Cendrars, who is able to contextualise his story and analyse the war with a lucidity that only the passage of time can provide, the most noticeable trait of the Great War seems to be its chaotic character -the complete lack of any capable organisational force is what stands out in most of the battle scenes, when the word hasard (hazard) and pagaie (disorder) are repeated time and time again: "I hurry to say that war is not beautiful […].Of all the battles that I have witnessed, I have brought back only one image, that of disorder. I wonder what the people are going to look for, when they say that they have lived historical or sublime hours." Military institutions, armies, and strategies -they all obey only of the Great War turns towards his inner self, shifting his focus on the personal experience and the purpose it could have for him, making the experience not just a collective one, but also a very personal one. However, amid all the fire and the fighting, the soldier barely has time to process any of it: "We don't have the time to judge or to form an opinion. Time is pressing. [...] The fortune of the arms is a matter of hazard." 29 The challenge becomes then, through art and writing, to regain a sort of control over the chaotic universe of the battlefield, "impose verbal order" and avoid the overwhelming feeling of meaninglessness that 30 such an experience might bring once the war is over. One way of doing this is demystifying a war that had been one of the main topics of discussions, as well as the source of inspiration for artists and writers for decades: "The purpose […] of telling the war 'as it is' and not as it is supposed to be, may come from the desire to demystify a phenomenon that centuries of histories had glorified." 31 Cendrars tries to remain closer to the truth by revealing some of the less heroic moments from the battlefield. For instance, the writer admits that, most of the time, the soldiers were confused about their role and had no idea towards where they were being led: "But what pissed us off was not knowing where we were or what we were doing there, and also that real smell of shit we were plunging into and which was surrounding us." This chaos escalates to even higher proportions in a battle scene, in 32 which the squad of Cendrars is being shot by French troops, unaware that they are shooting at their own people: "They started shooting at us from behind. Not the Germans. The French! Volley fires. The friends. Our people." The absurdity of the scene is also highlighted by the fractured 33 language, paralleling the thoughts of the writer, shocked by the scene and by the inefficiency of military leadership. Powerless in the face of such a brutal reality, the writer seems to resort to his own imagination in order to tell a truth that can't be revealed through a simple confession: "With all his natural tendency towards hyperbole, Cendrar's war stories are probably the most moving and true-to-life texts ever written on the reigning spirit of the trenches during World War I." Through his lenses, 34 the reader experiences the complexity of war and the different kind of memories it leaves the soldier with. Interestingly enough, Blaise Cendrars never really ceases to believe in the cause, never forgets how high the stakes are, even in spite of the devastations and the unnecessary brutality of the war; he hates the way war must be fought, as well as being on the battlefield, but continues to fight until the end for his adoptive countryan attitude to which most soldiers of the Great War would eventually confess to. Additionally, another attitude to which veterans could relate 35 and which can be found in the memoirs of Cendrars is the special, intimate bond which forms between members of the same squad, the nostalgic memories of the companionship born in the depth of the trenches, which no one, except for those present there, can relate to. These episodes are rare, yet endearing nonetheless: "I couldn't speak." Cendrars writes, as he is describing the Christmas Eve of 1914, "A smile was playing on my lips. It was nerving. But, deep down, I was happy. I shook Sawo's hand. Deep down, all four of us were laughing." For, if 36 at times war seems to lead to a loss of individuality, it also destroys all barriers of social classes and allows for bonds to form outside of the customarily class lines: "Central for the positive experience of the war was the sense of comradeship, or solidarity, which is a central feature of many of the memoirs and of the public reception of them." This results 37 into yet another paradox: even after all the horrors, the writer still finds pleasant memories between all the painful ones.

(Re)Creating the Battlefield

If Cendrars never loses sight of the reason for fighting, he does lose hope both in civilisation and in God, who appears to have turned a blind eye, leaving the soldiers to their own miserable destinies. Embarrassed by the horrors around him, aware of the war that would follow and losing all hope, Cendrars doesn't hide the odious face of the war that is usually left out of other accounts: "Angéli had died asphyxiated, his head in German shit, his legs towards the sky. Two thighs widened in the shape of a 'V'. A detail. Another corpse among the other thousands and dozens of thousands, all more or less grotesque. It's not possible. I have already said it. God is absent from the battlefields. He stays out of it. He is hiding. It's an embarrassment." 38 Using different language registers, the writer appeals to all the senses of the reader, recreating an eerie atmosphere of fear and chaos, authentic to the reality of the Great War, creating an aesthetic of horror, while also unveiling what is hidden behind the glorified image of the battle. For example, Cendrars' memoir is full of French army slang, so as to give the reader an impression of what the conversations between the soldiers sounded like: "poilus" is the term most frequently used to talk about ordinary soldiers, while the writer refers to the Germans almost exclusively as "Boches," a pejorative term used by the French during the First World War. Furthermore, certain accents of the characters are pointed out, a detail that adds to the authenticity of the text; Guidicelli, for instance, a Corsican soldier, is described as having a particular accent, rolling his "r." In this way, the reader not only 'sees' some words on the 39 pages of a book, but can actually play the voice of the character in his mind. The conversations between the soldiers of his squad are reimagined as dialogue, almost as if nothing is omitted -not the inside jokes of the soldiers, nor the indecent comments: "Through his consummate balancing of all shades of humour (broad, wry, tender, malicious, bitter, salacious) and Gothic horror, he probably achieved the most candid iconoclastic portrayal of the colossal absurdity that war really is." 40 Moreover, in his attempt to regain the atmosphere of the battlefield, Cendrars often resorts to descriptions of smells, wrapping the reader up into a world of senses, where everything suggests war and misery: the odour of "chemistry and decomposing bodies" is what persists most 41 ardently in the mind of the French writer and just the mention of it is enough to suggest to the reader the apocalyptic universe of the war. In addition to this, Cendrars' language is also heavily influenced by his poetical sensibilities, which means that, at times, very familiar language can be found right next to powerful metaphors or stylistic devices, which turn the experience of war into a work of art. The French writer uses many repetitions and metaphors, like the phrase "God is absent," a 42 motif that echoes throughout the narrative. Moreover, if one considers the memoir a literary genre that is supposed to be as close to reality as possible, the writer's preference for the absurd and the symbolic is all the more noticeable: "It is a complex montage, where the real and fictive paths of the labyrinth, as well as the chronological modifications, attain their paroxysm." In this way, the small anecdotes of his squad can be 43 understood as standing in for the reality of the Great War, as experienced by the individual.

The central symbol of the war memoir is, nevertheless, the hand that the writer loses in 1915 at Navarin, which also serves as title for the book and is depicted on the cover of the French edition from Folio, along with his regimental number that would come to define his identity as a soldier. The amputation of his arm is surely the event that marks a new time in the life of Cendrars, for whom the loss of his right arm is not only a constant reminder of the brutality of war, but also a tragic loss of the natural instrument of the writer. From that moment on, he must go 44 against his nature and either give up writing or learn to adapt, to create in a new way and use his left arm (which he will learn to do). Although not frequently mentioned throughout the war account, the severed hand does get its own short chapter towards the end of the memoir, a chapter in which reality becomes entangled in the fictional, creating a strange, surreal scene, its title, "The Red Lily," being also a nod to the work of Anatole France, in which the imaginary and the real come together. This 45 then means that the anonymous hand, found by Faval in the grass, is a metaphor: "It reveals that the war also creates surrealistic works of art, it composes its own aesthetic." In this sense, Cendrars describes the kind 46 of art that can result after the war: a disturbing image, a collage in which beauty and torture stand side by side in a shocking way, that is meant to leave the reader with a frown and a strange mix of awe and disgust. Only in this way is the writer able to portray war: by distancing himself from it and turning it into something abstract, "perceived through the camera eye of his mind and heart." 47

Literature Becomes an Old Soldier's Therapy

Finishing his writings nearly thirty years after having fought in the Great War, it is no wonder that his memories are influenced by all the events happening in between; Cendrars writes not only with the image of the Great War in his mind, but also with that of the Second World War. The bitterness is therefore doubled, as he is aware that The First World War and all the misery that it meant would not bring any of the positive changes that people had expected of it, on the contrary: it would only start a violent flame that would eventually lead to disaster. The constant mention of the failure of civilisation is then not only alluding to the grotesque deaths witnessed on the battlefields in 1914 or 1915, but echoes all the devastation of the Second World War, as well as the horrors of the concentration camps. For the same reason, The Bloody Hand can't Claire Maingon, Main coupée, main errante, main absente: Allégorie réelle de la Grande Guerre in 44 Annales de Bretagne et des Pays de l'Ouest, 2016: https://doi.org/10.4000/abpo.3401, p. 58, (acc. 12 th of August 2020) Claire Maingon, Main coupée, main errante, main absente: Allégorie réelle de la Grande Guerre, 45 op.cit., p. 62 Ibid., p. 64 be a memoir which tries to find a sense for the Great War, for any purpose which others might have found before him becomes irrelevant in the face of the following conflict, which the writer was living through while writing this memoir. Instead, it turns into an aesthetic, which will influence his other works as well: "The unspeakable reality of war may very well be one of the decisive factors which led Cendrars to take refuge in the inner realm of fantasy and create the mythic version of the world that constitutes many of his stories." As the writer is telling the story of 48 his war experience, one can observe his own wonder at the memories that pour out of his mind: "If writing is thinking and discovery and selection and order and meaning, it is also awe and reverence and mystery and magic." 49 At the end of the narrative, the writer contemplates once again the destiny of the human being, thrown into the war, as he becomes reduced to the number of his identification number: "Death… Birth… To what good!…" . The memoir ends as he is chosen at random -as all things 50 happen in Cendrars' war -to spend his permission, on the 14th of July in Paris.

Beyond the trenches, it seems as if the writer is hopeless when it comes to finding a purpose in the war. However, through literature, which had been his passion before the war, he finds a refuge when the fighting ceases, a healing space where emotions can be articulated, put into order and made sense of, where old friends can be brought back to life and given a voice. In turn, the experience in itself teaches Cendrars how to adapt his literary style to his artistic purpose: as he is struggling to remember and to form those past impressions into a coherent narrative, the poet becomes a memoirist.

  Cendrars, La main coupée, Gallimard Folio, Paris, 1975, p. 140 (my own translation) 2 Douglas Porch, The French Foreign Legion, Harper Collins Publishers, New York, 1991, p.xiii 3 Blaise Cendrars, La main coupée, op.cit., p. 378 (my own translation)

  Nichole T. Gleisner, Soldier-Poet or Écrivain-Combattant: How the French Trenches of World War I 5 Defined Witnessing, Studies in 20th & 21st Century Literature: Vol. 41, 2, Article 10. https:// doi.org0.4148/2334-4415.1929, p. 1 (acc. 18 th of August 2020) Jean-Claude Lovey, La Situation de Blaise Cendrars, Editions de la Baconiere, Neuchatel, 1965, p.6 63

Adam Piette ,

 Piette War Zones, in The Cambridge Companion to the Literature of the First World War by 11 Vincent Sherry (Ed.), Cambridge University Press, Cambridge, 2005, p.42 Monique Chefdor, Blaise Cendrars, op.cit., p. 113 12 Virginie Renard, The Great War and Postmodern Memory: The First World War in Late 20th-13 century British Fiction (1985-2000), Peter Lang Publishing, Bern, 2013., p. 299

24

  Paula S. Fass, The Memoir Problem, in Reviews in American History, Volume 34, Number 1,The 21 Johns Hopkins University Press, Baltimore, 2006, p.111 Blaise Cendrars, La main coupée, op.cit., p. 156 (my own translation) 22 Ibid., pp. 129-131 (my own translation) 23 Lauren Tatu and Julien Bogousslavsky: Blaise Cendrars Temoin de la Grande Guerre: La Guerre du

Blaise Cendrars ,

 Cendrars La main coupée, op.cit., pp. 174-175 (my own translation) 25 Blaise Cendrars in Blaise Cendrars vous parle…, by Michel Manoll (Ed.), Denoël, Paris, 1952, p.

Blaise Cendrars ,

 Cendrars La main coupée, op.cit., p. 13 (my own translation)

14 Ibid., p. 20 (my own translation) 15 Yuval Noah Harari, Renaissance Military Memoirs: War, History and Identity, 1450-1600 (Warfare 16 in History), Boydell Press, Woodbridge, 2004, p. 68

Blaise Cendrars ,

 Cendrars La main coupée, op.cit., p. 23 (my own translation) Classique Garnier, no. 54, Paris, 2016, p. 66 Geoff Dyer, The Missing of the Somme,Vintage Books by Random House, New York, 2011, p.47

	17
	Ibid., p. 65

18 Lauren Tatu and Julien Bogousslavsky: Blaise Cendrars Temoin de la Grande Guerre: La Guerre du 19 Poet Devenu Prosateur,in Feuilles de routes,

  La main coupée, op.cit., pp. 93-94 (my own translation)

	27	Blaise Cendrars, La main coupée, op.cit., p. 93 (my own translation)
	28	Yuval Noah Harari, Renaissance Military Memoirs: War, History and Identity, 1450-1600 (Warfare
	in History), op.cit., p. 46
		Blaise Cendrars,

29 Kate McLoughlin, War and Words in The Cambridge Companion to War Writing by Kate 30 McLoughlin (Ed.), Cambridge University Press, Cambridge, 2009, p. 19

  Catherine Savage Brosman, The Functions of War Literature in South Central Review, vol. 9, No.1:

	31
	Historicizing Literary Contexts, John Hopkins University Press, Baltimore, 1992, p. 89
	32	Blaise Cendrars, La main coupée, op.cit., pp. 86-87 (my own translation)
		Ibid., p. 88

33 Monique Chefdor, Blaise Cendrars, op.cit., p.115 34 Jean-Jacques Becker and Stéphane Audoin-Rouzeau, Blaise Cendrars et "La Main Coupée" in

  Memories from the Frontline: Memoirs and Meanings of The Great War from Britain, La main coupée, op.cit., p. 335 (my own translation)

	36	Blaise Cendrars, La main coupée, op.cit., p. 175 (my own translation)
	Jerry Palmer, 37
	France and Germany, Palgrave Macmillan, London, 2018, p. 308
		Blaise Cendrars,

one single force: the force of chaos. This is a common method for war memoirist to signal the individuality of the soldier, who is no longer part of the military machine, as it used to be in the past, but rather stands alone, opposing any political leadership. Alone in the crowd, the soldier

Poet Devenu Prosateur, op.cit., p.73

they are sentient beings, not simply masses of faceless humanity." The


Cagnelle Joseph

Metailler Thibaut

Pascal Amandine

Diagnostic de la maturité pour accompagner la transformation digitale des PME : une approche par la gestion des connaissances

Diagnostic de la maturité pour accompagner la transformation digitale des PME : une approche par la gestion des connaissances.

Auteurs :

Cagnelle Joseph, doctorant en Sciences de gestion, Aix Marseille Univ, CNRS, LEST, Aixen-Provence, France, ingénieur de recherche, Groupe Reel iT, joseph.cagnelle@reelit.fr Metailler Thibaut, Enseignant/Chercheur à l'Ecole des Mines de Saint-Etienne, thibaut.metailler@emse.fr Pascal Amandine, Aix Marseille Univ, CNRS, LEST, InCIAM, Aix-en-Provence, France, amandine.pascal@univ-amu.fr Soumission dans le programme général du colloque.

Le contexte actuel ainsi que la forte croissance technologique influencent grandement les organisations, tant dans leur fonctionnement que dans leurs propositions de valeurs. A ce titre, la transformation digitale dispose d'une place importante dans les stratégies et la performance des entreprises [START_REF] Hess | Options for Formulating a Digital Transformation Strategy[END_REF]. Cependant, cette transformation vient bousculer les schémas organisationnels par l'acquisition de nouvelles technologies [START_REF] Karoui | Transformation digitale : De l'assimilation des technologies de collaboration à la mise en usage[END_REF]. Dès lors, la littérature [START_REF] Karoui | Transformation digitale : De l'assimilation des technologies de collaboration à la mise en usage[END_REF] a mis en lumière les conditions d'acceptation et d'assimilation de ces nouvelles technologies dans les organisations en s'appuyant sur le modèle des capacités d'absorption de Boynton et al. (1994). [START_REF] Karoui | Transformation digitale : De l'assimilation des technologies de collaboration à la mise en usage[END_REF] mettent alors en évidence le lien entre la transformation digitale et la gestion des connaissances comme une garantie à l'acceptation effective des technologies par les collaborateurs notamment par la mise en place d'un climat organisationnel favorable. La notion de climat organisationnel pourrait alors renvoyer à ce que la littérature spécifique dans la transformation digitale a nommé la maturité digitale d'une organisation. Néanmoins si ce concept a été travaillé théoriquement, il reste assez difficile à opérationnaliser pour les praticiens. L'approche pas la gestion des connaissances permet alors d'apporter une grille d'analyse à ce concept notamment pour faciliter le déploiement de ce type de dispositif en faveur d'une stratégie digitale centrée sur l'organisation. De nombreux modèles de maturité digitale [START_REF] Teichert | Digital transformation A systematic review of literature[END_REF] et de gestion des connaissances [START_REF] Jiankang | Knowledge Management Maturity Models : A Systemic Comparison[END_REF] Approche critique des modèles de la maturité digitale [START_REF] Henriette | Digital transformation challenges[END_REF] proposent de définir la transformation digitale comme un processus de changement disruptif ou incrémental qui commence par l'adoption et l'utilisation de technologies numériques, puis évolue vers une transformation holistique implicite de l'organisation. Cette dernière repose sur l'établissement d'une stratégie digitale, dont le succès repose sur la maturité digitale, « qui renvoie à l'acceptation et l'exploitation des connaissances identifiées à travers la capacité absorptive. Il s'agit, en d'autres termes, de créer les conditions pour développer, de manière systémique, des usages appropriés des technologies numériques pour (et par) l'ensemble des acteurs de l'organisation » [START_REF] Ettien | Maturité digitale et capacité absorptive : Déploiement d'une stratégie de transformation digitale dans une entreprise agroalimentaire[END_REF]p.114). Si plusieurs modèles ont été développés dans la littérature [START_REF] Teichert | Digital transformation A systematic review of literature[END_REF], ces derniers sont principalement pensés pour les grandes entreprises et très peu tiennent compte des spécificités des PME [START_REF] Williams | Digital maturity models for small and medium-sized enterprises : A systematic literature review[END_REF]. Les travaux réalisés autour des modèles de maturité digitales de ces dernières sont soit techno centrés, tel que le modèle proposé par [START_REF] Grooss | Balancing Digital Maturity and Operational Performance-Progressing in a Low-digital SME Manufacturing Setting[END_REF], soit complexes, mettant en jeu plusieurs dizaines de dimensions, et impliquant donc une difficulté d'appropriation [START_REF] Kljajić Borštnar | Multi-attribute assessment of digital maturity of SMEs[END_REF]. Ces modèles sont principalement mobilisés dans une fonction descriptive [START_REF] Berghaus | Stages in digital business transformation : Results of an empirical maturity study[END_REF], offrant une photographie à un instant t de l'état d'une entreprise, et ne présentant pas une approche dynamique d'accompagnement à la transformation digitale. Ils présentent donc un certain nombre de limites, soulevant des questionnements sur l'appropriation et l'acquisition des connaissances permettant de les appréhender. De plus, la stratégie digitale qui en découle a pour finalité de rendre optimale les performances métiers. Cela passe donc par une capacité de l'ensemble de l'entreprise à « accepter les changements fonctionnels et/ou structurels induits » (Ettien & Peron, 2019, p.116), tout en transformant les usages. Les questions d'apprentissage organisationnel [START_REF] Karoui | Transformation digitale : De l'assimilation des technologies de collaboration à la mise en usage[END_REF]) et de gestion des connaissances apparaissent alors comme fondamentales dans l'accompagnement au diagnostic de la maturité digitale. Ainsi, à la lumière de ce que nous venons de voir, nous proposons de relativiser les approches technocentrées des modèles de maturité digitale existants en PME par une approche de la maturité digitale axée sur l'organisation et la gestion des connaissances, définie comme « tous process ou pratiques de création, acquisition, capture, partage et utilisation de la connaissance, pour améliorer l'apprentissage et la performance dans l'organisation » (Scarbrough et al. 1999, p.669).

Le lien gestion des connaissancesmaturité au service de la transformation digitale des PME

Si les modèles de maturité sont principalement utilisés de façon descriptive, [START_REF] Berghaus | Stages in digital business transformation : Results of an empirical maturity study[END_REF] montrent qu'ils révèlent également les dimensions qui doivent être conçues, et dans leur fonctionnalité prescriptive, ils permettent aux entreprises de définir les plans d'action ou les capacités nécessaires pour atteindre le stade de maturité souhaité. Comme nous l'avons vu précédemment, si les modèle de maturité se sont fortement concentrés sur la question technologique, l'approche organisationnelle reste quant à elle encore opaque tant dans la littérature que dans la pratique. [START_REF] Teichert | Digital transformation A systematic review of literature[END_REF] ressence les axes les plus présents issus des modèles de maturité digitale généraux (non spécifiques à un secteur), à savoir les dimensions liées à la culture digitale, à la technologie, les opérations et processus, la stratégie digitale, l'organisation ainsi que les compétences digitales et l'innovation. Des modèles de maturité de gestion des connaissances ont également été développés [START_REF] Jiankang | Knowledge Management Maturity Models : A Systemic Comparison[END_REF]. Ces derniers reposent aussi sur un certain nombre de dimensions de l'entreprise. Les plus récurrentes dans la littérature sont les processus métiers, la technologie, le personnel et la culture d'entreprise [START_REF] Jiankang | Knowledge Management Maturity Models : A Systemic Comparison[END_REF]. Nous pouvons nous rendre compte qu'il existe des points de convergences stratégiques entre les modèles de maturité digitale et de gestion des connaissances en croisant les dimensions qui les structurent (tableau 1). Les notions de maturité digitale et de gestion des connaissances possèdent donc des dimensions similaires, que l'on pourra considérer comme la technologie, la gestion RH (compétences digitales, personnel), la culture et les processus organisationnels et métiers. A la lumière de ce qui a été développé dans cette partie, il est possible d'établir qu'un lien conceptuel étroit existe entre ces deux idées. Intégrer la gestion des connaissances à la notion de maturité aurait alors du sens dans une optique de transformation digitale.

Dimensions issues des

Selon une première analyse de la littérature spécifique à la transformation digitale, les principaux modèles de maturité ne nous offrent pas de cadre pertinent à l'opérationnalisation de la mesure de la maturité digitale. Centrés sur la technologie, trop complexes ou encore par manque de dynamisme, ces modèles ont donc des limites qui ne favorisent pas la transformation digitale dans les PME. L'enjeu de cet article est donc de proposer une grille de lecture de la maturité digitale centrée sur l'organisation en analysant les dimensions présentées de la maturité par la mobilisation des concepts et outils de la gestion des connaissances Nous observerons alors dans la pratique l'implantation de ce type d'approche pour valider empiriquement des dimensions favorables à l'opérationnalisation de ce diagnostic dans les PME. Cet article s'inscrit dans le cadre d'un projet de recherche avec le groupe REEL IT. Les praticiens rencontrés ont par ailleurs confirmé les limites identifiées dans la littérature proposant ainsi une collaboration scientifique dont l'enjeu est de développer une méthodologie d'accompagnement à la transformation digitale.

  sont développés dans la littérature, mais aucun ne questionne leur lien dans la transformation digitale. L'objet de cette proposition de communication est d'interroger le rôle de la gestion des connaissances dans l'établissement d'un diagnostic de maturité digitale d'une PME. Cette communication s'inscrit dans le cadre d'un projet de recherche mené entre le groupe REEL IT, et des chercheurs d'Aix Marseille Université et l'Ecole des Mines de Saint Etienne.