Dr. Philippe Woloszyn
email: philippe.woloszyn@univ-rennes2.fr

OF VULNERABILITY SYSTEMS 2-SUSTAINABLE MODELLING OF GLOBALIZATION CHALLENGE

ABSTRACT: A PROGRAMMING MANUAL TO VULNERABILITY Globalization as progress of economic development has increased population socioeconomical vulnerability when unequal wealth distribution within economic development process constitutes the main rule, with widening the gap between rich and poors by environmental pricing. Econological vulnerability is therefore increasing too, as dangerous substance and techniques should produce polluted effluents and industrial or climatic risk increasing [START_REF] Woloszyn | Territorial intelligence of vulnerability systems -A transitional viewpoint of sustainable development[END_REF]. To illustrate and model this process, we propose to introduce an analogical induction-model to describe both vulnerability situations and associated resilience procedures. At this aim, we first develop a well-known late 80's model of socio-economic crack-up, known as "Silent Weapons for Quiet Wars", which presents economics as a social extension of natural energy systems. This last, also named "E-model", is constituted by three passive components, potential energy, kinetic energy, and energy dissipation, thus allowing economical data to be treated as a thermodynamical system. To extend this model to social and ecological sustainability pillars, we propose to built an extended E(Economic)-S(Social)-O(Organic) model, based on the three previous components, as an open model considering feedbacks as evolution sources. An applicative illustration of this model will then be described, through this summer's american severe drought event analysis.

SILENT WEAPON AS A MODEL OF UNINTELLIGENCE SERVICE

Silent Weapons for Quiet Wars was claimed beeing uncovered quite by accident on July 7, 1986 when an employee of Boeing Aircraft Co. purchased a surplus IBM copier for scrap parts at a sale [START_REF] Cooper | Behold a pale horse[END_REF]. Silent weapons technology is an outgrowth of a simple idea discovered, succinctly expressed, and effectively applied by the quoted Mr. Mayer Amschel Rothschild, who discovered the missing passive component of economic theory known as economic inductance. Currency, or deposit loan accounts, has the required appearance of power that could be used to induce people into surrendering their real wealth in exchange for a promise of greater wealth (interests).

When applied gradually, the public adapts to its presence and learns to tolerate its encroachment on their lives until the pressure (psychological via economic) becomes too great and they crack up, depending on their resilience capacity.

THE E S O LOCAL/GLOBAL TRANSITION PARADIGMATIC MODEL; ECONOMY AND ENERGY CONCEPTS

In the study of energy systems, three elementary concepts, potential energy, kinetic energy, and energy dissipation, constitute the base of pure physical counterparts called "passive components".

In the science of physical mechanics, potential energy is associated with a physical property called elasticity or stiffness, and can be therefore represented by a stretched spring. In electronic science, potential energy is stored in a capacitor instead of a spring, which property is called capacitance.

Sitio web: http://territoriosposibles.fahce.unlp.edu.ar/ La Plata, 17 al 20 de octubre de 2012. 1

Second passive component, kinetic energy, is associated with a physical property called inertia or mass, and can be represented by a flywheel in motion. In electronic science, kinetic energy is stored in an inductor, a magnetic field, which property is called inductance. Endly, energy dissipation is associated with a physical property called friction or resistance, thus converting energy into heat.

Model E assumes that economics is only a social extension of a natural energy system, also constituted by its three passive components. To extend this model to social and ecological sustainability pillars, we claim that Social and Ecological pillars could therefore be defined as subsystems based on the three previous passive components, which constitute a global open sustainability model, as seen figure 1:.

ECONOMIC INDUCTANCE (MODEL E SILENT WEAPON)

An electrical inductor has an electric current as its primary phenomenon and a magnetic field as its secondary phenomenon (inertia). Corresponding to this, an economic inductor has a flow of economic value as its primary phenomenon and a population field as its secondary field phenomenon of inertia. This public inertia is a result of consumer buying habits, expected standard of living, etc., and describes generally a self-preservation process.

SOCIAL INDUCTANCE (MODÈL S SOFT CONDITIONING)

The social welfare program is nothing more than an open-ended credit balance system which creates a false capital industry to give nonproductive people a roof over their heads and food in their stomachs. Analogy considers social implying cooperation action as its primary phenomenon and integration process as its secondary field phenomenon of inertia. As in every social system approach, stability is achieved only by understanding and accounting for human nature (action/reaction patterns).

ECOLOGIC INDUCTANCE (MODEL O ORGANIC ERADICATION)

Ecosystem, involving interaction between air (athmosphere), water (hydrosphere), ground (litosphere) and life (biosphere), is preserved within natural cycle between natural life cycle between producers (vegetals), consumers (living organisms) and de-composers (chimical materials). Ecologic inductor considers ecological management as its primary phenomenon and ecosystemic interactions as its secondary field phenomenon. A further description is given following figure 2: Within those analogical models, if capacitance exceeds inductance, a leading power factor will result which could result in uncontrolled economic/social overflows and harmonic problems occurs, driving the system to crisis.

CASE STUDY: HISTORICAL DROUGHT IN UNITED STATES

The United States is grappling with a widespread drought this summer as severe as the historic drought of the 1950s. The US Department of Agriculture (USDA) reported that 55 percent of the pasture and rangeland was in very poor condition. On July 25, the USDA designated even more drought disaster areas, bringing the total for the 2012 crop year to 1369 counties in 31 states (Figure 3).

INDUCED EFFECTS FROM O (ORGANIC-ECOLOGIC-CLIMATE) -> TO E (ECONOMICS)

With more than 40% of US agricultural land now in extreme or exceptional drought, "Prices of both corn and soybeans soared to all-time highs, with corn climbing more than 50 percent in the past four weeks alone due to the worsening drought, squeezing livestock producer margins." [START_REF] Cooper | Behold a pale horse[END_REF]. doing this business, I never saw such prices fluctuations" (Reuters, 2012), it is not the price level that borrows producers, but their fluctuation periods, which have passed from seasonal (between summer and winter, namely) to daily frequency, which causes market uncertainity by unpredictible price variations. Thus, entropy of the whole E S O system is collapsing, implying a global crisis risk in agri-food sector as well. With the ongoing drought expected to destroy or damage a portion of the field corn crop in a number of States, increase in the farm price of corn affects the price of other crops, such as soybeans, and other inputs in the food supply such as animal feed. This first (Organic-Economic) induction effect sawn figure 6 will then be followed with a second (Economic-Social) induction effect (Figure 7), thus squaring the vulnerability-sustainability triangle to enter a first induction phase leading to global crisis emergence. While drought planning and mitigation responsibilities lie largely at the state and local level, the federal government also provides some drought planning assistance.

Equipo TAG Territorios Posibles UNLP-CONICET y Universidades asociadas del GDRI Groupe de Recherche CNRS INTI International Network of Territorial Intelligence Instituto IdhICS, Facultad de Humanidades y Ciencias de la Educación, Universidad Nacional de La Plata -CONICET

RESILIENCE TO DRAUGHT? GOVERNANCE RESPONSES

As illustrated figure 7, when a drought is declared for a locality or region, U.S. Secretary of Agriculture sets in motion a series of alerts, recommendations, activities, and possible restrictions at the local, regional, or state level, depending on the drought length and severity. Ultimately, a multi-year severe drought could initiate a federal response and transfer of federal dollars to the affected area. In response to the 2012 drought, USDA also has taken a variety of administrative actions. For example, it reduced the interest rate for emergency loans from 3.75% to 2.25%, a smaller reduction (10% instead of 25%) on rental payments, or the purchase of up to $170 million in livestock and fish products to help ease the financial effects of drought on meat and catfish producers. [START_REF] Shields | [END_REF]. Congress may evaluate whether current federal practices could be supplemented with actions to coordinate, prepare for, and respond to the unpredictable but inevitable occurrence of drought. In passing the National Drought Policy Act of 1998 (The National Drought Policy Act of 1998, P.L. 105-199), U.S. Congress found an increasing need at the federal level to emphasize risk management, albeit unpredictability, of severe drought occurring [START_REF] Leggett | CRS Report RL34266, Climate Change: Science Highlights, and CRS Report R41973, Climate Change: Conceptual Approaches and Policy Tools[END_REF]. It also may consider proposals to manage drought impacts, such as assisting localities, industries, and agriculture with developing or augmenting water supplies [START_REF] Folger | Drought in the United States: Causes and Issues for Congress[END_REF].

By increasing economical capacitance of agricultural product units (farms), the federal government enable socioeconomical resilience to increase social capacitance, and therefore, to avoid social risks due to insufficient feeding supply (see "Trespassing the Hunger Line", in [START_REF] Woloszyn | Platos poor city and rich city: Towards an inequality multidimensional evaluation[END_REF]. If this governance action increase the inductive fields of socioeconomical actions, this short-term federal response has to be completed with long-term policy rules concerning land use, polutant emissions, and environmental preservation, in order to enable socioecological resilience to "square" the whole E S O system resilience. As a major consequence, to solve climate-related production problems, the way people act together through coordinated cooperative actions will be essential for eco-social capacitance long-term increasing, and therefore, resilience induction enabling. The message from climate scientists may soon be sinking into the nation's consciousness, to enable convergence between decision-making and cooperation actin to take care of our common biosphere.

A CONCLUSION

As fundamental thermodynamics claims that in response to warming, dry regions will become drier and wet regions will become wetter, one can observe that "the 'rich get richer' " mechanism is already operating, enlighting the close relationships between socioeconomical and socioecological vulnerability processes. The observed speedup of the water cycle is "double the response projected by current-generation climate models, and suggests that a substantial (16 to 24%) intensification of the global water cycle will occur" in a world that will be 2° to 3°C warmer [START_REF] Durack | OCEAN SALINITIES REVEAL STRONG GLOBAL WATER CYCLE INTENSIFICATION DURING 1950 TO 2000[END_REF]. Severe drought can cause significant economic harm, by exacerbating water competition: uncertain availability of water is a greater risk to society than climate warming itself.

To manage this alea, reducing vulnerability through resilience process has to be a common goal between governments, organisations and citizens. Federal fragmented approach without local land uses acknowledgement can not assume that investment in drought preparation, mitigation, and coordination could produce significant socio-economical efficient outcomes. Therefore, response to systemic crisis like this recent USA drought has to be scaled from local level, at relatively short time scales (i.e. implying people's cooperative actions to bring immediate answers to water supply for agriculture) to global level, with implying long-term solutioning of the socioeconomical effects of climatic events, in order to reduce risk and uncertainty of climate change for vulnerable populations, through the increase of their resilience.

Figure 1 :

 1 Figure 1: Open-analogical model of sustainability involving territorial intelligence concepts

Figure 2 :

 2 Figure 2: The three passive components of the sustainability pillars

  Figure 3: U.S. Drought Monitor (Reuters, 2012)

Figure 4 :

 4 Figure 4: The three passive components of the U.S. climate event As said Bruce Williams, Kansas-Phillipsburg agricultural cooperative director: "since 31 years

Figure 5 :

 5 Figure 5: Temporal Phase Transition of E-O System Figure 5 illustrates the temporel phase transition between climate event and socio-economical outcomes. Severe drought of United States has immediately impacted the agricultural prices, with an incresing of +26% for corn and +41% for wheat at the international market.

  Figure 6: First (Organic-Economic) induction effect: phases 1&2

Figure 7 :

 7 Figure 7: Second (Economic-Social) induction effect: phase 3

Figure 8 :

 8 Figure 8: E S O System Resilience applied to U.S. 2012 Drought

  Equipo TAG Territorios Posibles UNLP-CONICET y Universidades asociadas del GDRI Groupe de Recherche CNRS INTI International Network of Territorial Intelligence Instituto IdhICS, Facultad de Humanidades y Ciencias de la Educación, Universidad Nacional de La Plata -CONICET

  Equipo TAG Territorios Posibles UNLP-CONICET y Universidades asociadas del GDRI Groupe de Recherche CNRS INTI International Network of Territorial Intelligence Instituto IdhICS, Facultad de Humanidades y Ciencias de la Educación, Universidad Nacional de La Plata -CONICET

Sitio web: http://territoriosposibles.fahce.unlp.edu.ar/ La Plata, 17 al 20 de octubre de 2012.


Of modernity as heritage, of heritage as future

Caecilia Pieri, Ph.D Head of the

spur of nation-building. 5 Last, the Mesopotamian period had being particularly highlighted by Saddam's regime to enhance a new legitimacy through an ideological continuity between the ancient and current Iraqi identity. 6 Nevertheless, in Iraq there is a general feeling that "the new" is more valuable than "the old", -given that the "old" in question is a "recent old" when compared to the "ancient". Lastly, the political troubles in Iraq since several decades, particularly severe during the 13 year-sanctions and the last war (2003), entailed functional instability resulting in the lack of qualified staff, evanescent or even lacking services in organizing appropriate administrative schemes with trained officers or servants. 7 All these factors explain how the study of modern architecture and urban planning as heritage became a kind of "blind spot" in Iraq. This heritage was rarely documented locally, to the exception of several attempts in the 80s and 90s, which never had time or opportunity to develop. 8 To sum up most of local opinions I have gathered for eight years, even within academic or professional circles, the 1920-1960 Baghdad suffers from the burden of an Orientalist prejudice: the mythical image of the vanished Abbassid Baghdad masks the real city, which is never seen for what it is, but for what it is no longer. This lack of consideration contests any identity to the modern city. 9 Also, it is not yet the new capital which emerged from the national revolution: this post-revolutionary Baghdad had created its own elite via the first Department of Architecture within the College of Engineering (1959), under the mastering of Iraqi foreign-educated architects who elaborated a new pride together within a new architectural environment. In other terms, until recently the Baghdad of the Hashemite monarchy was not even seen, stifled as it was into a despised "in-between" status.

I would like to propose a personal re-evaluation of the urban and architectural modernity of XXth century Baghdad by "reading" it in terms of heritage, i.e. of cultural achievement, societal process and collective memory, and perhaps in the light of a future collective project. My approach is based on the principles underlying the 220-year French experience in that domain, the theory, the practice and the management of modern heritage, itself based on the statement that the modern must be preserved for the present is the past of the future.

By producing such a voluntary statement, I hope to raise some public awareness about the vernacular, urban modern heritage of Baghdad seen as an important part of the Iraqi heritage, both prestigious and meaningful.

French heritage protection: main historical phases

The current corpus of French heritage was established in several phases.

The first French law protecting historical monuments was enacted in 1792, after three years of looting and voluntary destruction all over the national territory in the aftermath of the 1789 Revolution. 10 The first revolutionary government had to face the following debate: "What shall we do with the properties of the Kingdom and the Church: shall we destroy them as the symbol of a hated regime? Shall we preserve them as our History? Shall we keep them for we, the People, and transform them so that we can integrate them in our new collective project?" Most of the time, the third solution was adopted, so that the founding stone of the 5 On the use of archaeology as an ideological and symbolic stake during the XXth century in Iraq, see Bernhardsson 2005, passim. 6 . See Méténier 2006. 7 What happened in Iraq may be compared to other places, for instance in "reframed" 1990 Warsaw. See Czarniawska 2000. 8 See Bianca-Fethi 1983, but also the studies by Layth Raouf and Khalid al-Sultani. 9 See Pieri 2008. 10 The Church's properties were nationalized in October 1790 , those of aristocrats who emigrated abroad in November 1791, and those of the Kingdom in September 1792.

new society was actually a re-founding one, which kept the prestige [and the know-how] of the old one to turn it into a collective and prestigious framework for the new social and cultural vision of the country: 11 it seems quite a paradox, which was called the "revolutionary conservation of the Ancien Regime's properties". 12 The second stage occurred after another serious uprising, the French Revolution of July, 1830, when Louis-Philippe, the roi bourgeois (the "middle class King") appointed the historian Ludovic Vitet in 1831, then the writer Prosper Mérimée in 1834 to become the first "Inspectors of Historical Monuments"; he also created the official Commission des Monuments Historiques in 1837. 13 The third and capital stage happened once again after a Revolution, the third one, in 1848. Louis-Napoléon Bonaparte, who was elected President of the French Republic, became Emperor after a coup d'Etat in 1851. With the baron Haussmann, who was the governor of Paris district, he launched a new urban policy and transformed Paris according to their vision of what a capital should be: modern, and under control. The straightening of the urban design followed two main principles, which would become a topos among the European colonial urban policies: the tropisms of sanitation and modernization, inherent to any imperialist design; and the wide street, which, at the very centre of Paris 14 destroyed most of the urban pattern dating back to the Middle-Ages, in order to make urban revolts impossible such as that which had recently occurred during 1830 and 1848 revolutions. 15 In parallel to this ambiguous policy of "renewal by erasing", and as its exact counterpoint, the French Emperor launched the first policy of complete, systematic and accurate surveying, documenting, archiving, restoring and even reconstructing of the heritage all over the national territory. Teams of architects and painters were supervised by the architect, theorizer and conservationist Eugène Viollet-le-Duc. During the Third Republic, in 1882, the first Museum of Compared Sculpture was established, followed by the first academic teaching specialized in history of architecture and conservation/ restoration of heritage buildings. It is during this period that the corpus of theoretical and technical tools for the new scientific discipline of heritage/patrimonial process was forged.

Before World War I, this "patrimonialization" policy 16 entailed the institution of heritage as a national good, and the birth of cultural tourism. The law of December 31, 1913, was enacted to protect historical monuments and the Caisse nationale des monuments historiques was created in July 1914. It was the first State organization entitled to manage public subventions for maintenance and paying visits of historical buildings which had formerly belonged to the Kingdom and the Church and now belonged to the State, and also historical sites such as prehistoric caves, Greek or Gallo-Roman ruins on the French territory. 17 Last, during the prosperous post war years preceding the petrol crisis, ("Trente Glorieuses" 1950-1980 period), the 1960s witnessed the booming of national and international tourism with different laws to protect and enhance not only the monuments, but also the country's environmental resources via a huge planning of land development (mountains, seaside, countryside, protected valleys and regions). Finally, in 1964, after 20 years of official Reconstruction in the aftermath of the terrible destructions due to the US and UK bombings during World War II, André Malraux, the reknown author and Minister of Culture, and André Chastel, an art historian specialized in the Italian Renaissance, founded the "Inventaire Général des Monuments et des richesses artistiques de la France" (General Survey of French Monuments and Artistic Treasures). Their purpose aimed explicitly at preserving endangered data, knowledge and memory, as both of them foresaw a new coming age of large-scale destructions in the name of modernizationand it would be the case all over the world from the 60s to the 80s… Thus, it can be said that the French policy, philosophy and economy of heritage, were born from the direct experience of wars, violence and destructions on the national territory: they gave a concrete application to the desire of preserving the built memory of the countryancient, but modern as wellin the name of the general interest. Also, the efficiency of this policy is mainly due to the fact that enjoying heritage is not seen as a cultural privilege reserved to privileged segments of the population; and it became a basis for most of ulterior heritage policies in the world.18 « From the cathedral to the spoon », or from unicum to typicum Since 1964, in France we protect all kind of items transforming the country daily into heritage, "from the cathedral to the spoon". 19 This is based on what modern techniques of investigation in archaeology can reveal from a simple spoon when found in a Mesopotamian grave, for instance: culture, techniques and craftsmanship (style, decor), economy, industry and trade (materials), sociology (owner, type of grave), anthropology (food remains), etc. According to the principles of the French Inventaire Général (General Survey), the notion of protection does not aim at "freezing" the object in a museum window. It consists in several phases :

APPENDIX I, Main phases of heritage protection in France

-identification and documentation, as accurately as possible, following a precise and scientific methodology established since 1964; -information available to everybody via a web data bank, under the shape of a descriptive catalogue; -decision about what will be done in terms of protection, or not; even when some items get destroyed for various reasons, the information about them remains to be used by historians, architects, urban planners, any other private or public decision makers.

Official referenced categories are architecture, including all elements of a building which range from grounds to roofs; also, its numerous sub-categories, such as social housing, garden-cities, seaside and resort heritage, private mansions, etc; built heritage with all kind of sub-categories: educational, commercial, rural, industrial, sports, infrastructures, public buildings such as administrations or hospitals, and, at last, "places of memory" and preserved sectors. Thus, some items can be recent or modest, but each of them has its exemplarity as a landmark of identity, whatever it is, or embodies collective or civilian values. In other words, nowadays the concept of heritage ranges from the unicum to the typicum.

Protecting items of a generic modernity

These items, sometimes whole ensembles, have been classified according several categories. The first one addresses what could be called a generic, or iconic modernity in the field of space-building. Modern urban sites include whole cities, such as Le Havre, a millenary city which was totally destroyed during World War II and then rebuilt in 1950 by Perret brothers arch. ; it became UNESCO World Heritage in 2005. But some low cost housing cities, too, are preserved not necessarily for their architectural value but because they represent a key stage in the building history of modern France. Some are famous, as buildings by Le Corbusier in Marseille, Rezé, Firminy, Briey or Pessac. Some other are less well known, such as the Cité des Dents-de-Scie (Gutton arch., 1931-MH 1992): but the heritage value here consists in the witnessing of a new kind of societal organisation, contemporary of a new stage of industrial development, of family organisation, of relationship individual/ community/ work.

Modern vernacular houses are preserved, even when they are private villas, such as picturesque mansions of the Belle Epoque or more recent architect's masterpieces dating back to the 1960s or 1970s. But modern buildings representative of specific constructive techniques can be listed too, such as the Tour Albert in Paris (Albert, Boileau and Labourdette arch., 1960), which is famous for its structure in steel tubes.

Space building and technological field include of course infrastructures, which are considered as important witnesses of the daily life: typical bridges, viaducts or dams; water supply, lighthouse, transports: airport, metro stations... A certain quantity of the XXth century railways stations are now protected although still in use, and it is also true of some airports: the Paris airport of Le Bourget (Labro arch., 1937) has been partly transformed into a museum of aviation and a place for trade fairs, but is still used as a small airport for official personalities.

APPENDIX II Databases of the French Ministry of Culture

http://www.culture.gouv.fr/culture/inventai/presenta/bddinv.htm http://www.inventaire.culture.gouv.fr Mérimée. Created between 1978 and 1995. Built heritage : domestic, religious, agricultural, industrial, military, funerary, commercial, of craftsmanship, schools and unviersities, hospitals and gardens. About 200 000 items aver about 20 000 towns. From Prehistory to 1970. Palissy. Created between 1978 and 1995 for objects which are in the buildings registered in « Mérimée » (for existing works or items, remains, destroyed items or projects) : fines arts (painting, sculpture, graphic arts), objects, domestic , monumental and religious furniture, glass-windows, music instruments, industrial heritage, navy heritage (sea and rivers), scientific tools, ironwork, etc. Mémoire : photos. Created in 1995 : 275 000 images. Urbanism and architecture : religious, public, domestic, industrial, of craftsmanship and commercial ; civil engineering, gardens, objects, religious, civil and domestic furniture; music instruments; scientific tools ; engineering machines, motors, etc. international exhibitions, historical events, reportages, portraits. Archidoc bibliographic files. Created in 1997 : about 70 000 files, for XIXth and XXth century only. Urbanism and architecture : religious, public, domestic, industrial, of craftsmanship, commercial ; civil engineering. Thésaurus gathers a set of common vocabulary to all these databases. Each database can be accessed separately. Common informations which are useful to identify the items are in each base, so that surfing from one database to any other is easy.

Of built heritage and its intangible meaning

Deriving from space building, a second category could include all what documents the life of the country considered in its ethnology/ethnography. Because of their activity, commercial buildings, hotels or simple shops are very often partly preserved, usually the façade. It is an interesting compromise which does not hamper business by allowing internal transformations or modernization. All kind of wide spaces were re-converted since the 1980s, for instance the area of the former main slaughterhouse of Paris-la Villette (XIXth century, 55 hectares), located in what was once the northern fringe of the capital. It has been reconverted into a huge natural and architectural area (design by Tschumi arch., 1980) which includes a palace for trade fairs, theatre performances, exhibitions (Reichen and Robert, eng.); the offices became a theatre. On the remaining area, a complex of new buildings was erected: museum of Sciences and Industry (Fainsilber arch., 1980-1986); City of Music, with museum and national school of music (Portzamparc arch., 1991-1995); there are also restaurants, cinemas, circus, huge playing-games area for children and walking paths along the Canal de l'Ourcq, along which the former mills and factories have been preserved and transformed into housing and artists workshops. On the green area, many families come on Sundays for picnics, and by Summer, a giant screen allows thousands of people to see movies in the openair, for free, at night. All this has transformed the whole neighbourhood into one of the most successful meeting point of social conviviality in Paris.

For the same reason, industrial buildings, including railways systems and mines are protected not only as structures but also as places of memory for industry: various kinds of factories are frequently converted into museums, or research and educational centres in the field of their former activity. For instance, a water supply factory (Loewy arch., 1901, listed 1993) became a research centre on hydraulics and waste water treatment.

Educational or leisure buildings are protected too, although still in use for culture, sports, entertainment, so that both the built envelope and the use of the building are seen as heritage. Swimming pools, stadiums (Gerland football stadium in Lyon, Tony Garnier arch. 1926, listed 1967) can become historical protected buildings…. As to the movies-theatres and cinemas in Paris, most of them were built in the 1930s and 1940s; many of them were destroyed in the 70s in the name of modernization. Now, almost all the remaining ones are protected, not only as buildings but as cultural intangible heritage. Urban objects can be protected, such as urban « furniture»: public fountains (Wallace fountains), advertising columns (Morris columns), road sign-posts...

Last, places of memory (referring to Pierre Nora's concept of "lieux de mémoire") must be understood in a very broad meaning, ranging from war memories to houses belonging to personalities, artists, writers, famous characters: the German concentration camp and gas chamber of Strutdhof (Alsace), the German batteries of concrete blockhaus all along the French Atlantic Coast, Le Corbusier's cabanon in the South of France, the sculptor Rodin's house in Meudon near Paris.... We can easily infer from such classifications that the notion of typicum is never neutral, as it results from something which lays between the arbitrary and the consensus, whatever it is. Actually the notion of built heritage, although it differs from intangible heritage, has nevertheless something intangible. Therefore, the built tangible envelope and its intangible meaning or context are not dissociable: it is what makes their ambivalence.

In Iraq: from the mosque to the isment balât?

To begin with, the Baghdadi river panoramas from Jadriya to Kadhimiya are highly noticeable, as they offer a remarkable example of horizontal river-cityscape typical of the traditional characteristic Arab-Muslim city. Baghdad is probably the last one among the Arab capitals to give such an example of a visual specific continuity, whose evidence is given by the striking parallel between XIXth century images of its panorama and contemporary views of it. In such respect, this urban river-panorama is in itself an exceptional historical testimony.

In a way, many neighbourhoods and urban ensembles of the XXth century Baghdadi cityscape, taken as a whole, tell a meaningful urban history. This is true for the oldest ones, from 1915 to 1930: Rashid street in Rusafa, which, if properly restored, could pretend to become World Heritage including every building from Abu Nawas-Bab Shargi to Bab al-Muaddham and determining a preserved sector along both sides, East (Hafidh al-Qadi square, Shorja, Bab-es-Sheikh), West (Nahr Street ). It is also very true for Battaween (from 1926/ 1928) with its straight streets, open wooden sculpted verandahs, delicate brick decors, neotraditional schemes with covered centred halls, which testify to a successful example of composite new middle-class, typical of the formation of Iraqi nation-building. It is true, then, of Abu Nawas, the harmonious perspective of which along the Tigris is unique and punctuated with 1930-1970 houses which, for their most part, are gorgeous although sometimes in a dilapidated condition.

Among the 1930-1970s architectural period, some neighbourhoods are particularly rich in gorgeous houses and should be preserved as a whole, too, under certain conditions, 20 after getting rid of their degrading elements and without forbidding demolitions providing it would entail the strict control of any renovation or new construction: Waziriya -Aywadhiya, Adhamiya-Raghiba Khatoon north-east; Karrada -Abu Nawas, Saadoun, Masbah-Jadriya, south-east; Karkh-Salhiya-Shawaqqa centre-west. And, last but not least, one remarkable segment is the urban scheme formed by al-Amin/ al-Wathba/al-Kifah street, which was, in 1937-1939, the first modern urban tracing with two-story buildings designed under the supervision the first Iraqi architect, Ahmad Mukhtar Ibrahim, also the first to become Architect of the Government in charge of the Public Works.

Also, some neighbourhoods constitute the first examples of modern cooperative housing and access to ownership on a large scale ever built in Iraq: Tobshi, Washash, Baghdad Gharbia, the housing compounds built by the Iraqi Raiways, or by the IPC (Iraq Petroleum Company) in the North…..Advertizing publications of that time used to present them as an achievement to be proud of. If by chance some or part of these compounds were still intact, at least some items of them should be preserved not for their aesthetic performance but because they might be appropriate to new impulses and integrated processes of social restructuration.

From New-York to Dubai, and from Shanghai to Paris-La Défense, "Manhattan-type" neighbourhoods have become a compulsory parameter of globalization. But any perspective of sustainable development entails the re-thinking of the "BCD" concept (Business Centre Development), typical of US cities which had been built from nothing. Erasing the old citiescentres belongs nowdays to an obsolete ideology, which tends to be replaced by a new balance between existing areas and new areas, between preservation and development.

In Baghdad itself, several neighbourhoods could be more adapted to welcome such highrising developments, for instance al-Alawi which, on the Western bank, between Mansur, Shawaqqa and Salhiya, has already appropriate geographical and functional advantages. It is somehow a city-gate neighbourhood situated at a strategic crossroad between the two main axes coming from abroad (West and North-West). 21 Thus, Baghdad could become the last Arab capital capable of preserving its unique formal, chromatic, visual and functional centrecityscape as a whole, while allowing other neighbourhoods to be developed, as it has plenty of empty spaces within its boundaries.

The eclectic decor of typical Baghdadi housing during the 1930s and the 1940s, is far from being merely a blind mimicry of the West. Most of this housing was built by Iraqi ustawat at the maximum of their art, technique and invention. Each house represents a unique ensemble. The repertory of sculpted details testifies to a creative hybridity which mixes vocabularies coming from Mesopotamian tradition, Mediterranean Antiquity, Islamic and regional tradition, and European contemporary fashion. The resulting synthesis has its idiosyncrasy which differs from what is found in the neighbouring countries at that time, either in brick or in moulded concrete. This mastery, although not "avant-garde", is quite sophisticated and inventive, as it adapts a long tradition to new fashions. Some aspects of this symbiosis could constitute either what Anthony King calls a post-modern vocabulary, or even, an alternative modernism. 22 Most of the houses today still retain a large part of their decorative apparatus. Curtains of electric cables or new concrete walls very often hide elegant iron-works, such as the typical "peacock-feather" motive or Art Deco geometric patterns. Under the dust of oblivion or the machinery of a saw-mill, hundreds of cement tiles patterns (isment balât) transform the 21 Also, it is already punctuated with important buildings, such as the Ministry of Foreign Affairs, the National Iraqi Museum, the International Railways West Station, the Bunnia Mosque… It is not far from other important buildings such as ministries -Planning, Justice, Housing -, other administrations or cultural centres -Baghdad Governorate, Iraqi Contemporary Museum of Art, Rashid complex (to be restored). Lastly, it is very close to the Tigris and the city-centre, with the Tower of Telecommunications (in restoration), the buildings of the Mayoralty of Baghdad and Water Supply administration… house-floors into shimmering precious carpets. Not to mention the beautiful carved doors, the delicate brass handles, the aesthetic quality of solid interior furniture, in imported teck or even sometimes mahogany, or the coloured-glass windows whose modern shapes and patterns follow the technique and spirit of the ursi windows.

Among the modern "historical places", some played a specific role in the building of the modern spirit in Iraq: the first Olympic Club in Adhamiya23 , or the cinema Firdaous, (Ahmad Mukhtar Ibrahim arch.); the Zawra movie-theatre (Rasheed Street, Ibrahim al-Naddaf arch., 1933) which was a place for debates and meetings for the generation of the Revolution... or also famous artists' houses among which Jabra Ibrahim Jabra's or Faiq Hassan's house, which witnessed many meetings and discussions between artists, and could have been protected as a memory of the Baghdadi modernity.

From 1950 to 1980, lots of Iraqi and foreign architects, well known or less well known, gave Baghdad an amazing variety of "modern heritage" buildings on various scales, ranging from bridges to stations, administrations or anonymous modernist houses. Plot buildings, particularly, develop interesting solutions by adapting the modernist vocabulary and typologydouble skin façade, sun-breakers, columns, porches, etcas an alternative to traditional and regional demands.

What can be called "national" heritage?

What do we call French heritage in France? Above all, the style is not what makes an item become heritage: the French Parliament, for instance, is a mixture of Greek and Roman traditions. And among the 43 180 items which are officially listed as "XXth century Protected French heritage and historical monuments" we find a Greek style villa: Kérylos, South of France (Pontremoli arch. 1908, protected 1966); the main Mosque of Paris, of Moroccan style a cinema of Egyptian style, the Louxor (Zipzy arch. 1921, protected 1981); the Moresque building of the Art and Archaeology Institute in Paris ( Bigot arch., 1930, protected 1996); a German Bauhaus style villa Villa Cavrois, near Lille (Mallet-Stevens 1932, protected 1990); a Japanese pagoda, the Cinéma La Pagode in Paris etc.

Of course some periods led to characteristic "French styles" in architecture: the French Renaissance, the Loire castles, the French classicism "Grand siècle", i.e. the XVIIth century such as in Versailles, the French "Art nouveau", etc. But generally speaking, is considered as French heritage any kind of item which has been built on the French territory and to this extent, has become part of the French landscape, identity, history, whatever its style.

In fact, beyond the question of style, the idea of national heritage requires a process of appropriation of the heritage by the people. If we take the example of the shanashil, there is no doubt that it is Iraqi. But this typology of oriel can be found in many countries with conservative societies and narrow streets system because of the climate. Therefore, if it is Iraqi, it's not from its style (despite the specificities of the Iraqi shanashil), but rather because with the passing of time -since the Abbassidsit became part of the Iraqi urban landscape and was appropriated by the people, as the iconic symbol of the "traditional Iraqi house"24 .

We can find another and striking example of appropriation of an allogenic architecture in Erythrea, where the typically fascist Italian colonial architecture has been totally reappropriated by the people and reincorporated into their national heritage. It can be found now on the official website of African architecture. 25 In several other countries, (Syria, Lebanon, North Africa), European-style modern architecture of the former colonizers became "national" heritage. The same could be true of Iraq with its modern Iraqi heritage: I mean in particular not only the splendid buildings built by the British, but also the first "urban verticals" of the 50s, such as the Daftar Dar Building or the Khan Pasha building, both built by an Iraqi pioneer architect, Abdullah Ihsan Kamil, or the collection of "plot-buildings" 1930-1960 in Baghdad, which constitute a very special conservatory of urban housing forms.

Urban context as consensus -and sometimes as compromise

An urban context provides « something » which is much more than the mere addition of its parts: it is an intermingling of forms and functions, new and old, and often a compromise between successful facts and failures. This is the main reason why in most of the countries where laws exist since the early XXth century, the notion of heritage has been extended to blocks and neighbourhoods, even whole towns, such as landscape units or vast territories combining various natural elements or human, although it greatly complicates their management.

Speaking of house, we speak of a living household made of interwoven relationships between educational and representational patterns, individual and collective projections, links with the cultural, social and political collective environment, etc. In this respect any urban reformulation which takes place at the core of the city must incorporate formal and functional continuity and diversity into innovation, at least to a certain extent. From that point of view, the overall reshaping of Baghdad that was planned in the 1980s,26 was much more than a physical change. What happened in Haifa Street was a total erasing of entire neighbourhoods in Karkh, on the West bank, of what either had kept traces of the pre-modern urban fabric, or had been built during the 1930s as a residential area for a high bourgeoisie and their westernized mansions. Then Saddam Hussein ordered the building of housing ensembles for chosen upper-middle classes, together with cultural and official facilities. Such a neighbourhood was supposed to embody the new affirmation of a new affluent class, in what became the grand axe leading from North toward the president's privileged neighbourhood, Karradat Maryam (today the "Green zone"). Of this gigantic demolition enterprise, only nine houses survived: they were perfectly restored from the architectural and technical point of view27 , but today it can be said that they have lost part of their meaning since the neighbourhood they were part of has disappeared. Haifa Street is still a residential area, but it offers a striking contrast between the deserted main artery with no shops, no passers-by, no activities, no trees, no life at all, and the vivid, teeming, overcrowded and busy areas next to it, all situated in the older neighbourhoods along the Tigris (Shawaqqa, Kraimat).

Today, modern urban utopias are becoming obsolete, because they cannot suit any sustainable long-term vision of development, and because they have proved to be often aggressively destructive or illusory. But thirty years ago, all around the world, the 1970s and 1980s were the more destructive decades in the name of the so-called "modernization", as they aimed at transforming the urban fabric and the way of life on radical basis. Paris itself is a good example of a successful ensemble with some huge mistakes dating back to both decades. One of the most visible of them is the Tour Montparnasse, with which Parisians must cope: it is a huge isolated tower, which spoils all the urban perspectives and panoramas of the very centre. 28 The worst was the destruction of the main Parisian market-hall (half covered/half open-air), Les Halles, built by Baltard in the XIXth century, which constituted a neighbourhood that was alive 24h out of 24h. It was replaced by a huge mall, the biggest problem of which is not its quite vulgar architecture, but its urban disruption. During daytime, it is crowded and safe; but at night it becomes dangerous (gangs, drug dealers' traffic…).

Obviously such an urban failure has complex reasons; but among the main ones is the fact that it erased a whole lively neighbourhood to transform it into a place of mere consumerism with no other social value. At night, shops are closed and consumerism is off: the place becomes a huge public vacuum, which cannot be secured by private guards. The failure is such that there was recently a public demand for a restructuring of the whole. After several years of public consultation, enquiries and an international competition, it will be implemented, and it will cost billions of euros.

The destruction of the Paris Halles became a point of no-return, and since then we, French, learnt from our mistakes: the Centre Pompidou was built without erasing anything (there was a car park before) (Piano and Rogers arch., 1976). From the beginning it was designed to be not only a museum for tourists, but above all a collective landmark and source of activities for citizens of Paris; thus, it has been the opportunity to create a new social and collective value. 29 The European notions of heritage and of city are linked: both entail that diversity should be preserved and organized as a whole and as a collective value, as the city is the place of shared space (even if only partially) by various people whatever they come from. For that reason, surgical gestures aiming at systematically levelling odd details or idiosyncratic uses of the city might be harmful on the long term. One aspect which has been emphasized by the French writer Victor Hugo, who was an activist in the field of national heritage, is the fact that « The building belongs to its owner, but its beauty belongs to the people »: this sentence was written in 1832 in a very famous article published with the title "Guerre aux démolisseurs" (Fighting against demolishers). Hugo vehemently advocated the notion of beauty as a national good and collective interest, which became one of the basic principles of French idea of heritage: the landscape, urban or natural, has and is a collective value which cannot be altered without a certain consensus. Such a consensus should imply at least a minimum adhesion between the individuals and the community. Their particular interest lays in the respect the law, as the law is not seen as something which deprives them of their liberty: it is a constraint which has a cost, but it is the price to pay to be part of a shared sense of civic space.

Highlighting the principle of reconversion/adaptive re-use. The patrimonialization of vernacular heritage is fairly recent and has to be envisioned in parallel to the development of globalization: in Europe, the heritage becomes the warrant of an identity threatened by open borders and barriers. In this respect, the re-conversion of existing structures or buildings may prove to be more expensive in the short term, but more successful in the long term, in terms of collective prestige and social cohesion. In France, as elsewhere in Europe, modern heritage buildings are either still in use, such as dams or private houses, or converted to other uses. For instance, because of its proportions and size, industrial heritage proved to be particularly adapted to educational uses -for universities, high schools and colleges-, or research activities -sometimes in continuity with the former use-. Rural heritage becomes often a centre for local/agricultural tourism and information, or for craftsmanship. According to the principle of re-conversion, the persistence of forms and spaces can be subject to renovation with no destruction, and to re-conversion toward another life. In such projects, the "soul" of the former function gives a place its unique character, its value, and this value has to be understood in terms of both real estate and prestige, economic and symbolic.

In an urban regeneration process, the city is not seen as a museum, as a fixed image forever, inasmuch as it generates a new attractiveness, new activities, new dynamics and new incomes. Once restored and rehabilitated, any kind of building or neighbourhoodfactory, mill, port, hospital, castle....can become a new starting point for the territory, such as occurred in the case of the La Villette neighbourhood of Paris. In some aspects, the new area which was developed in London around the Tate Modern museum is very similar: a former industrial heritage which was transformed into an art museum, with free entrance for the public, free areas which became a crowded place for walking, meeting, playing... Heritage implies an investment, but primarily, imagination: most neighbourhoods of the Paris centre before were poor, dirty and collapsing; they are now clean, extremely expensive -a new problem still to be solved in order to counterbalance speculation and gentrification. In the same way, some neighbourhoods of Baghdad-centre today, such as part of (among others) Battaween, Aywadhiya, Adhamiya, Waziriya, Kraimat or Shawaqqa which are poor, dirty and extremely dilapidated, could become a fantastic urban centre with beautiful houses if properly restored.

Conclusion:

no future without a (modern) past. Heritage is not isolated from the urban context, and this urban context is not only the product of collective practices: it is also the producer of them. Also, heritage is not only transmission of the past, it is mainly a collective project. So at this point we should ask: what collective memories shall we protect, to build what collective project? Understandably, the question is highly delicate in Iraq today, but Iraqis mustn't shun this issue, so they can come to terms with it, sooner or later, and whatever the solutions found.

The successful achievement of an urban context does not lie on abstract decisions on paper. It is a complex process, subject to negotiations and conflicts as it requires time and daily appropriation of the people itself. It is a paradox that the people, although the first stakeholders, are not the decision makers, and when heritage and development are articulated only in terms of "architecture" and "tourism", and when the capitalistic investment is the major triggering event, this kind of development is more a façade for business. On the contrary development, such as heritage, should embody negotiated consensus, whatever the shape and the extent this consensus take. Obviously, as the French notion of heritage derives from a specific history, this heritage became a landmark and a practice of city-making, itself linked to modes of leaderships and of governance. The participation of the citizens became part of urban policies because of the progression of the civilian society and urban middleclass.

But what does the "participation into public action" signify for individuals or citizens who have always been excluded from urban policies? Until today civilian societies in the Middle-East witnessed a gap between the experts and the simple citizens. These citizens were generally deprived of access to the destiny of their urban environment, which was characterized by the absence of negotiation, regulations or deregulations from above, or global laissez-faire. But this could change, not only because of the recent societal and political shift in the Arab world: several examples in countries of urban East Africa show that urban citizens, far from being inactive, launch various initiatives, most often outside formal structures. When their interests are threatened, they organize themselves in groups or local associations which negotiate with public institutions. 30 In Baghdad, one of the most delicate aspects of the question lies probably in the complexity of its fabric, which reflects the complexity of its population and history. In the 1980s, the Iraqi Palestinian critic Jabra Ibrahim Jabra wrote about "Baghdad in a perspective of time": he invoked Babylon a city of pluralities, where all languages, religions, races and cultures could be found. 31 But the immediate future of Iraq will have to deal withamong othersthe issue of sectarian antagonisms, which has led to a new urban fragmentation and will imply a delicate process of re-composition, re-vitalization of the city. This leads to raising the issues of institutional accountability and civil responsibilities of the rulers, together with the appropriation of the urban space, understood as a common/shared space for multiple communities. Shared heritage and shared public space should be enhanced in parallel, for a city with fragmented spaces, fragmented populations and fragmented social bodies goes back to pre-modern ages and cannot face the long term future properly.

In such a perspective, the XXth century heritage of Baghdad, if restored, renewed and incorporated into a perspective of development, could become a key "missing link" between the city's past and future. Once again, the challenge is not to "sanctuarize" Baghdad, from Kadhimiya to Jadriya, as a museum. Nevertheless, it would be risky for the Iraqis to deny the architectural and urban quality of such or such neighbourhood under the pressure of economy, as no identity can be built from scratch, even if it can seem easy to copy such or such model, in particular the so-called "Dubaisuccess-story-model": production of iconic images and spectacles which are detached from the "local" and reflect the global flows of money; short term valorization; territorial partitions and control, with clusters and specialized zones; terraforming as image-making, blurring the real present with an imaged future; non-sustainable over-mobilisation of critical resources, etc. 32 Last but not least, in Iraq as in any other country, but maybe more than in any other country, the dilemma of the XXIth century will be to re-evaluate the rich potentialities of its modern heritage. Indeed the main challenge will be firstly, to give this "inherited modernity" an opportunity to nourish the future and secondly, to protect it from the jeopardizing illusions of a quick -show off-ready-made "renewal" induced by the impersonal and alienating laws of the market. In other terms, rather than "bigger, higher, faster, further", I'd rather advocate Sonallah Ibrahim's phrase, Lâ mustaqbal bidûn mâdî: no future without a (modern) past.

22

  Anthony King, in Nasr-Volait 2003.

  Patrice Beghain, Le Patrimoine: culture et lien social, Paris, Presses de Sciences-Pô. Bernhardsson 2005: Magnus T. Bernhardsson, Reclaiming a plundered past: archaeology and nation building in modern Iraq, Austin, University of Texas Press. Bianca-Fethi 1983: Stefano Bianca, Ihsan Fethi, Giorgio Lombardi, Sohiko Yamada, « Baghdad Historical Center Rehabilitation Project »; vol 1: «Inventory of monuments of cultural interest »; vol. 2: «Social conditions»; vol. 3: «Macroframe Study», Baghdad (unpublished) 30 See Legros 2008. 31 Jabra 1985. 32 I am referering to Dr. Waleed Hazbun's lecture during the 2011 City Debates (American University of Beirut): 'The 'Dubai Model' and its Effects: Tourism and the Political Economy of Place-Making » .

1. September 16, 1792: temporary conservation of "art works threatened by the revolutionary troubles" 2. 1795: Creation of a General Council of the Civil Buildings 3. 1796: Creation of the Museum of French Monuments 4. 1837: Creation of the Commission des

	Monuments Historiques (Committee of Historical
	Monuments) 4. 1913: Label MH « Monument historique" for architecture, which entails a preserved surrounding
	perimeter of 500 metres, not to be built or changed without a special permit.
	5. 1964: Heritage listed among the « Inventaire général des monuments et des richesses artistiques de la France" (General Survey of French Monuments and Artistic treasures).
	6. 2003: ZPPAUP (Zones de protection du patrimoine architectural, urbain et paysager): preserved sectors, understood as "architectural, urban and landscaping heritage".
	7. 1989: Cities of Art and History: a special label given to municipalities which have demonstrated a
	consistent heritage policy in terms of preservation, funds, manifestations, educational programs; this
	label allows the mayoralties to ask subventions from the State as to such or such project.
	8. 2000: Special Label « XXth century Heritage »: to this very day, it concerns about 1500 items, which
	deserve special criteria

of analysis and possible restoration, adapted to modern materials and environments

http://www.culture.gouv.fr/culture/organisation/dapa/historic-dapa.htm. This short paper deliberately ignores the fields of ethnologic and intangible heritage, which would be beyond its scope.

In UK, the Royal Commission on the Historical Monuments of England, founded in

1908, protected first historic buildings dating back to "the early XVIIIth century." Then in 1921 the limit was postponed to 1714, after WWII to 1850, before being abolished in 1963. This means that anything of recognized heritage, even very recent (building, monument, landscape or neighborhood), may be protected from destruction. See Edelblutte 2008.19 A phrase which has always been used in France for 40 years to describe the extension of the field of heritage; it is also the subtitle of[START_REF] Heinich | La Fabrique du patrimoine. De la cathédrale à la petite cuiller[END_REF]

It would entail first important budgets to establish consulting, enquiries and social participation of local majlis for each mahalla, to re-think the complexity of the area in order to preserve the existing social links and create some new urban dynamics.

The name was Royal Sporting Club, then it was changed into the Republic Sports Club, then now the Adhamiya Club for Sports.

Some images among the Maqamat illustrated by the Baghdadi painter Al-Wasiti (XIII th century) represent stylized constructions which could be shanashil (seeWarren-Fethi 1983).

Website: www. archiafrika.org.

This was part of a whole remodeling of the city into eleven new areas. See "Madinat as-Salam", Process, special issue, 1985.

The restoration was led by a British-Iraqi team including John Warren, Ihsan Fethi, Nicholas Wood, etc.

There is also an urban highway along the Seine, (the "Voie sur Berge"), which proved to be such a failure that now on Sundays it is closed to cars and open to pedestrians; and even transformed into a beach one month every summer! This points out that an urban population cannot be deprived of a direct link with the river.

Speaking of compromise, the church of Montmartre in Paris was erected by a reactionary government to commemorate its triumph and the massacre of

000 persons during the French civil uprising of 1871 called "La Commune". For that reason, the people of Paris don't like this monument, but with time we accepted it: it became part of Paris' landscape and is visited by 10 million tourists a year. Source : http://www.paris.catholique.fr/-Saint-Pierre-de-Montmartre-.html.


available at the local level, and result in some heterogeneity of the geometry, arrangement and even strengths of the various stones of the wall, which are not taken into account by existing theoretical approaches:

• The model based on periodic homogenisation of masonry [START_REF] De Buhan | A homogenization approach to the ultimate strength of brick masonry[END_REF] as a regular block stack cannot take the stone variability or movement into account. • The Discrete Element Method (DEM) used to model dry stone masonry by Dickens [START_REF] Dickens | Use of distinct element model to simulate behaviour of dry stone walls[END_REF], Harkness [START_REF] Harkness | Numerical modelling of full-scale tests on drystone masonry retaining walls[END_REF] and Claxton [START_REF] Claxton | Rigid block distinct element modeling of dry stone retaining walls in plane strain[END_REF] gives remarkable results for large displacements, but knowledge of stiffness parameters is required. These parameters are difficult to determine by experiment, particularly because of the strong heterogeneity of the walls. Modelling the real geometry of all blocks requires considerable work. • the FEM used by Zhang et al. [START_REF] Zhang | A finite element analysis for the stability of dry stone masonry retaining walls[END_REF] has similar problems to DEM.

An alternative approach was therefore preferred, with a simpler model based on experimental observations, one more easily adopted in engineering practice. Experimental tests were conducted to characterize the constitutive elements of the wall (the stones, and the interfaces between them), and then the masonry itself, using hydrostatic loading of full scale walls.

This article is structured in three parts. The first part presents the experiments carried out in the laboratory on components of the wall: interface shear tests between two individual stones, and between two beds of stone.

The second part describes the proposed theoretical model, which considers the stability of the wall as a homogeneous structure on a rigid foundation. Its originality comes from the fact that it takes account of the characteristics of the material -the irregularity of the geometry of the stones and their arrangement -using the parameter Θ, measured on site, which is the slope of the internal shear band compared to the initial stone bed. It is shown that it is necessary to take into account this internal failure, because it leads to the instability of the structure.

The third part presents the experimental in situ loading test of five walls by hydrostatic pressure. These tests were carried out on dry stone walls of 2 and 4 m height, built by skilled masons, in conformity with current and traditional best practice. They made it possible to quantify and validate the parameters of the model for two types of stone: limestone and schist.

Close attention was paid to displacement measurement analysis during the experiments, because the model cannot give information on displacements. The use of stereophotogrammetry [START_REF] Desrues | Mesure du champ de déformation d'un objet plan par la méthode stéréophotogrammétrique de faux relief[END_REF] on the end elevation of a length of wall allows determination of local displacements on an entire section of wall, thus checking the two-dimensional displacement behaviour. This information was compared with observations using sensors on the front elevation, and with the direct measurement of the parameter Θ.

Mechanical behaviour of "dry stone" material

The integrity of a dry stone wall is related to the stones which make it up. But Villemus [START_REF] Villemus | Etude des murs de soutènement en mac ¸onnerie de pierres sèches[END_REF] showed that the compression strength of stone within a wall height lower than 6 m, which represents approximately 90% of existing walls in France on the national road network, seems sufficient. On the other hand, in the case of soft foundations, the compressive strength of the soil is critical in determining the dimensions of the wall.

Interface behaviour measured by the shear test

The shear strength of dry stone beds must be high enough to limit the displacement of the stone, in order to guarantee monolithic behavior of the wall. As a first investigation, the interface behavior between two cut stones was measured on samples 6 cm × 6 cm and 30 cm × 30 cm, using a shear box 30 cm × 30 cm at the LIRIGM of Grenoble and a traditional 6 cm × 6 cm, direct shear box. The cut sample faces removed the problem of macrorugosity.

However, to measure in a more realistic way what occurs in situ, shear tests were also carried out using a very large shear box, allowing the effect of interactions between the stones due to a wall's vertical and horizontal joints to be taken into account. In addition, this made it possible to represent correctly the macrorugosity of the various stones. The prototype shear box of 100 × 100 cm 2 [START_REF] Aboura | Etude expérimentale et mise au point d'une boîte de cisaillement pour caractériser les déchets ménagers[END_REF] at LIRIGM of the Grenoble J. Fourier University was used. This allowed dry stone to be made in the lower box, to be sheared by a second bed, assembled in the upper box, Fig. 1.

For the filling of the lower half-box, the stones were selected so as to ensure a relatively flat upper surface of the stone bed, lying as close as possible to the shear plane of the box. Once arranged, the stones were wedged in place using small stones.

During the filling of the upper half-box, the vertical joints were crossed carefully to avoid continuous vertical joints across the shear plane. Wooden wedges and stiff barbed polymer geomembranes were placed between the stones and the horizontal plate of the shear box to ensure that all the stones had at least one contact with the plate transmitting the vertical load.

The vertical load produced an average normal stress varying from 30 to 130 kPa, roughly equivalent to the base of a wall 7.5 m high at the upper end. The shear rate was not constant, but was kept below 3 mm/min. The test was carried out on the same sample four times, with increasing values of normal stress. The displacement response from this procedure may not be equivalent to the real shear displacement, but this does not have serious implications on the calculation of the parameters c m and the ϕ of the Coulomb law. During the test, stones sometimes broke by flexure, especially under high loadings. The surface of the stones was abraded, especially by sand created by crushing of the stone, as shown in Fig. 2.

Cohesion is always neglected, since it is induced by the very large shear box. The angle of friction obtained is close to that found by the other shear boxes, Table 1. It is extraordinary that the test with the small shear box makes it possible to directly obtain the friction at the interface between two stone beds. Following this finding, the angle of friction of the schists of "St Germain de Calberte" used in Section 4 was only measured by the 6 × 6 cm 2 shear box.

Limit equilibrium analysis of a dry stone masonry retaining wall

Dry stone retaining walls are load bearing retaining walls, which have long been analysed by considering the equilibrium of forces and moments applied to the wall treated as a rigid solid. This assumption is checked by determining if the resultant force lies within the central third of the foundation. In current engineering, external forces are usually obtained using the earth pressure coefficients given by Caquot et al. [START_REF] Caquot | Tables de butée et de poussée[END_REF]. However, the test walls described here were loaded by water, giving simple hydrostatic pressure → p w , with no shear component on the back of the wall, see Fig. 3.

A priori, a dry stone wall cannot be regarded as a rigid solid, even if the middle third rule is satisfied at the level of each stone bed, so that the wall is carrying the vertical compression throughout. A potential internal shear failure within the masonry AO (see Fig. 3) is defined by the angle θ and the height h o where it emerges at the wall face, Fig. 3.

Wall behaviour assumptions

The following assumptions are made regarding the behaviour of the wall:

• There is no interaction between failure by the sliding/shearing of joints, and failure by rotation. • The friction mobilised in shearing in the joints in the wall is given by the stone-stone friction measured in the laboratory, and corresponds to a pure Coulomb type of angle of friction ϕ m , see Section 2.

• The inclination of the failure plane for shearing on the dry joints is given by an angle θ to horizontal, which may differ from the orientation of the construction bedding planes at an angle η to the horizontal. The inclination of the failure plane relative to the bedding planes is given by Θ, Fig. 3. This is because the irregularity of the stones allows rotation, crushing or displacement as the load is applied.

The two parameters, angle θ and height h o , are thus characteristics of the wall construction, geometry and loading. They must be measured by experiment. The height h o is a priori null if the foundation is a soft soil. The first stone bed will punch the soil, allowing rotation to the angle θ. In the case of the experimental walls, the foundation was rigid and one to two joints were necessary to enable rotation. We are assuming h o = 0 gives larger loads, and so errs in the direction of safety.

Internal stability

If a linear stress distribution is assumed within the stone beds, the sections of the wall always remain compressed when the resultant force stays inside the central third of the wall section, which limits the relative eccentricity to k = 1 6 . As the dry stone construction has no tensile strength in the joints, if the resultant lies in front of the middle third, then there is no compression at the back of the wall, and the linear stress distribution starts from zero at a point which moves closer to the wall face as the eccentricity increases. Considering the moment equilibrium about the front of the wall gives a limiting value k = 1 2 . Between 1 6 and 1 2 the wall is still potentially stable, but as the value approaches 1 2 , the vertical stresses increase rapidly, reaching infinity at k = 1 2 . The simple assumption of linear stress distribution would, of course, be incorrect well before this stage is reached, if it is ever even approximately correct in a dry stone wall, which tends to deform primarily in shear rather than in the pure bending which is implicit in the assumption of a linear stress distribution.

In order to evaluate internal shear stability, the equilibrium of the forces is examined, Fig. 3. There is stability when the interface friction angle ϕ m is high enough to allow the horizontal forces to be resisted. This is quantified by the safety coefficient F g :

F g = V tan(ϕ m -θ ) H (1)
with V and H being the resultant forces from the external forces applied to solid OACB. Though very simple, the calculation cannot be carried out without full-scale experiments to give the values of θ and h o , and to validate the method of calculation.

Loading test on full scale dry stone retaining walls

Five walls were constructed for this study, with varying geometries as shown in Fig. 4, with maximum heights up to 4 m (walls 3 and 5). The use of rough stones from local quarries, St Gens limestone for walls 1-4, and schist from St Germain de Calberte (France) for the fifth, conforms to local practice for construction of such walls. The use of schist for wall 5, a denser stone with lower friction, in thinner pieces, makes it possible to test the reproducibility of the model on a another type of stone.

Experimental device

The five walls were built by skilled dry stone masons (see acknowledgement). In Fig. 5 the particular heterogeneity of the geometry of the stones and the relatively regular stone beds can be seen. The presence of a batter (walls 1, 3, 4, 5) is in conformity with the majority of existing walls, and helps prevent overturning failure. Moreover, the batter makes the construction process slightly easier if the stone beds are perpendicular to the wall face (walls 4 and 5). The initial slope of the stone beds increases the internal shear strength of the wall.

Instead of using earth pressure to load the walls, hydrostatic pressure (in the form of water in a large PVC-lined bag) was applied. With no friction on the back of the structure, and a loading more precisely predictable than would be obtained from a compacted fill, this allowed the study to focus on the internal shear strength of dry stone masonry. These tests as a result do not make it possible to study the interaction between the wall and the embankment, but the effect of this can be estimated elsewhere using conventional practice, starting from the knowledge already established for the retaining walls, [START_REF] Caquot | Tables de butée et de poussée[END_REF]. Each wall was weighed after testing, so that together with measurements of the volume of the wall, the masonry's unit weight could be obtained, Table 2. For example, wall 3 was built with twenty-nine tons of stone.

Displacements measurement

From 8 to 10 displacement sensors measured the movement of the central section of the face of each wall during the loading. To supplement these measurements, photographic slides of one side of the wall were taken from a fixed point. The stereophotogrammetric analysis of these slides enabled the displacement of each stone to be determined, allowing the:

• comparison of the movement of the central part of the face measured by the sensors with the movements on one end of the wall at the same time, and hence validation of the assumption of plane strain.

• determination of the kinematics of failure, by observing the slip lines as well as the overall rotation.

The particular use of stereophotogrammetry in this project involves the photographic recording of two images of the same plane object undergoing a plane strain. The two images are photographed from the same place, but at two different times. Slides measuring 6 cm by 6 cm were used. When viewed with a stereoscope, a false relief appears where there has been displacement within the plane between the two images. This false relief is proportional to the displacements which have occurred, and can be observed and recorded using normal stereographic procedures. This work was done in Laboratory 3S of Grenoble (data stereo-scope and processing). Further details of the technique are given by Desrues [START_REF] Desrues | Mesure du champ de déformation d'un objet plan par la méthode stéréophotogrammétrique de faux relief[END_REF].

The displacements determined have an accuracy limited by the scale factor. The measurements on the images allowed an accuracy of +/-0.005 mm. Wall 3, which was 4 m high, was represented by 51 mm on the slide, giving a scale factor of 78.4. The resulting accuracy of displacement measurement was +/-0.4 mm, similar to that of the cable sensors.

The strain field was obtained using the Anadef software developed by Desrues [START_REF] Desrues | Mesure du champ de déformation d'un objet plan par la méthode stéréophotogrammétrique de faux relief[END_REF]. From the points measured by a stereoscope, this software carries out a triangulation of the measured displacement field, the material being regarded as continuous, and hence mapping the strain tensor. The fourmetre high walls comprised about 30 stone beds, each bed including 6-10 stones from the front to the back of the wall. The simplification of continuity for the purposes of stereographic mapping of displacements was thus found to be acceptable for qualitative interpretations.

Wall 5 loading test analysis

Only the results of wall 5 are presented in detail here. The full results are given in Villemus [START_REF] Villemus | Etude des murs de soutènement en mac ¸onnerie de pierres sèches[END_REF]. The model presented in Section 3 gives the following requirements for stability of the walls:

• k for overturning: marginal stability in the range |k| < 1 2 , certain stability for |k| < 1 6 , • F g for translation: stability for F g > 1.

Displacements of the front face

The study of the movement of the front face of wall 5 (Fig. 6) showed the following characteristics, which had also been shown by the other walls:

• As the load increased, the wall remained a monolith until a load corresponding to k = 1/6 (F g > 1.

2). Beyond this load, the internal displacements were high but the wall remained stable. • The wall is sheared from the base, the shear band increasing with the loading. The Fig. 7 shows the wall before and after the failure. The belly-shaped deformation may be seen from both ends of the wall. Even after high displacements, the wall remained stable thanks to internal reorientation of the masonry, which is characteristic of the material.

Fig. 8(a) shows the relationship between displacements of points of the facing obtained from the cable sensors at the middle of the wall and the height of the water applying pressure to the back of the wall. These curves are of the same type as those obtained by direct shear testing of the stone interface. Full frictional strength was mobilised with displacements of just a few mm.

Comparison with stereophotogrammetric data

Stereophotogrammetric measurements were obtained for the entire cross section of the wall on the end elevation, whereas the cable sensors relate to the median of the external face of the wall. It is thus useful to check if the movement of the wall was uniform along its length, so that the measurements obtained by the two methods were the same. In Fig. 8(b), for the slide pair 01-03, the results obtained by the two methods are seen to be close together. The levels of loading corresponding to the slides are shown in Fig. 8(a). This indicates that the hypothesis of plane behaviour was correct.

The maps of the displacement vectors from slide pairs 01-04 are given in Fig. 9(a). The end section of wall photographed was not visible entirely, because the formwork retaining the PVC liner containing the water hid 30 cm of the back of the wall. The contours of displacement measured by stereophotogrammetric analysis therefore do not cover the entire cross-section of the wall. Nevertheless, a good representation is given of internal displacements of the wall, since the visible part corresponds to 80% of the total surface of the section. For clarity, the displacement vectors are drawn to an exaggerated scale. The measured area after deformation is represented on Fig. 9(a) by the dotted line.

The displacement vectors of (Fig. 9(a)) highlight the kinematic nature of the failure, which is an overall horizontal slip (pair 02-03 and 03-04). There is a rearrangement of the stones at a downward angle of approximately 11 • (pair 01-02); for the following pairs, the slip tended to be approximately horizontal on the first "free" dry stone bed (located above the bed blocked by the foundation), and very slightly tilted (2.5 • downwards) for the second "free" bed.

The failure of wall 5 was localized at the base of the wall; the remainder of the wall had a behavior under loading which was close to a rigid behavior, Fig. 9.

Summary of the 5 tested walls at failure

A clear distinction has been drawn between the shear slip and internal overturning failure mechanisms, described by independent factors of stability. All the walls (given in Fig. 4 and Table 2) showed shear (slip) failure mechanisms, and therefore Eq. ( 1) can be used for all the five walls. Walls 2 and 4 also displayed overturning mechanisms in conformity with the model.

The dry stone retaining walls' specific mechanism of failure, namely internal shear, was characterised by means of the parameter θ, which is the inclination of the slip failure compared to the horizontal. It is then possible, using Θ = -η + θ, to define Θ in relation to the form of the construction, i.e. in terms of the stone shape and the masonry quality.

It is now possible to calculate the value of θ, and therefore Θ for the full-scale tests, using Eq. ( 1) and the experimental values of the failure load measured on site. φ m , η and h w were measured, the last giving p w and then H . The unit weight was measured on site, giving V ; then letting F g = 1 to represent the failure state enables the calculation of the theoretical θ, and hence Θ, in Table 3. The calculated values of Θ range from 5.5 • to 11 • , obtained on five tests and two types of stone (limestone and schist).

In order to use this simple model in practice, it is necessary to make the assumption that Θ will always be approximately in the range 5 • -11 • , on the basis of the observations of walls 3, 4 and 5 (Table 3), for two types of stone (limestone and schist). If this assumption were found to be valid for a wider range of geometries and loading conditions, then Θ could be regarded as characteristic of dry stone masonry retaining walls in general. Then the calculation of F g for any geometry and any load condition would enable simple design and assessment in practice.

Conclusions

The aim of sustainable construction and development has given rise to work within the European Region aimed at rehabilitating the use of dry stone masonry. This article aims to support the development of a scientific basis for its analysis and design, in order to reintroduce dry stone into current civil engineering practice.

In this article, our modelling follows a very pragmatic approach, by simplifying dry stone retaining walls as homogeneous, but taking into account their specific real characteristics, namely the problem of internal stability due to the shear planes naturally made by stone joints. Laboratory experiments showed that the interface shear behavior of these walls is governed by a pure friction law (non-cohesive), which does not depend on the sample size.

Then full-scale tests on dry stone retaining walls loaded by a hydrostatic pressure were analysed by stereophotogrammetry. This analysis described the internal mode of failure by shear (slip), which occurs after a local rearrangement of the stones that results in a rotation Θ of stones, leading to the failure slope θ. Knowing the initial slope η of the dry stone beds of a wall (compared to the horizontal), and having an estimate of the values of Θ for two stone types, the relationship θ = Θη may be checked.

Therefore, it is easy to take into account the internal shearing of a wall on a slope of θ, which differs from that of the initial stone bed, by using a simple equilibrium model. The calculated factor of stability of the slip, F g , describes this type of failure satisfactorily, with the sliding occurring for values of F g close to 1 (F g = 1 ± 0.07).

Fig. 1 .

 1 Fig. 1. Two stone beds inside the LIRIGM shear box 100 cm × 100 cm.

Fig. 3 .

 3 Fig. 3. Geometry at failure, η initial inclination of stone beds.

Fig. 4 .

 4 Fig. 4. Tested wall geometry. The hydrostatic load is applied on the left side.

Fig. 5 .

 5 Fig. 5. Wall 5 construction; left: stone size heterogeneity, right: wall basement construction.

Fig. 6 .

 6 Fig. 6. Wall 5, left: wall facing displacement for varying relative eccentricity k; right: horizontal displacement u versus stone position y 2 with a dilated scale.

Fig. 7 .

 7 Fig. 7. Wall 5, left: before loading, centre and right: after loading "belly shape".

Fig. 8 .

 8 Fig. 8. Wall 5, left: horizontal displacement u for 2 facing stones. Slides 02, 03 and 04 (resp. k = 0.173; 0.232; 0.296). Right: face stone displacement by 2 methods.

Fig. 9 .

 9 Fig. 9. Wall 5, from left to right slide pairs 01-02, 02-03, 03-04, (a) displacement vectors, (b) distortion.

Table 1

 1 Friction angle measured by 3 types of shear test

	Stone name	6 × 6 cm 2 box,	30 × 30 cm 2 box,	100 × 100 cm 2 box,
		cut samples	cut samples	uncut samples
	Limestone from fields	37 ± 2 •	37 ± 1 •	38 ± 2 •
	Limestone of "St Gens"	36 ± 1 •	36 ± 1

• Not measured Fig.

2

. Lower stone bed after shear testing of two stone beds 100 cm × 100 cm (limestone). The white zone consists of crushed pieces of stone.

Table 2

 2 Geometric and mechanical data about tested walls

		Wall 1	Wall 2	Wall 3	Wall 4	Wall 5
	Height h + h o (m)	2	2	4	2	4.25
	Free height unblocked at the basement (m)	1.85	1.85	3.85	1.90	4.10
	Top width (m)	0.6	0.9	1.2	0.65	1.16
	Basement width (m)	0.9	0.9	1.8	0.9	1.8
	Batter f1 (%)	15	0	15	12	15
	ε	0.5	0	0.5	0.38	0.5
	Volumic weight (kN/m 3 )	15.4	15.0	15.7	16.0	18.0
	Void percentage	25	27	24	23	32
	Stone friction angle (in degree)	36 limestone	36 limestone	36 limestone	36 limestone	28.5 schist
	Inclination of stone bed	Horizontal	Horizontal	Horizontal	η = 4

• η = 8.5 •

Acknowledgements

The authors would like to thank P. McCombie (University of Bath, United Kingdom) and A.S. Colas (ENTPE) for their valuable corrections to the text. The experiments could be made thanks to many partners: the dry stone masons from "muraillers de Provence" and "Artisans Bâtisseurs en Pierres Sèches", the "DIREN PACA", the "département de Vaucluse", the "commune du Beaucet" (R. Bouvier), the "Chambre de métier de Vaucluse" (C. Cornu), the APARE (P. Alexandre and J.B. Lanaspèze), the quarry "Mallet", the "Parc National des Cevennes", the FFB, "Chambre de métier de Lozère", "Maisons Paysannes de France", "commune de St Germain de Calberte". We thank also J.P. Gourc, H. Mora, P. Goteland and Y. Orengo from the LIRIGM for the use of the large shear boxes, and finally J. Desrues (Laboratory 3S) for allowing us to use the stereophotogrammetry device, and C. Rousseau for assistance in its use.