Méthodologie de Diagnostic des Tunnels et Ouvrages Souterrains en Service – MéDiTOSS

The main goals of the project are:

1. the evaluation of the current state of the various components of the structure. Therefore, a set of monitoring tools adapted to the site constrains will be tested and the processing of some tools under development will be improved in order to provide the localization and the importance of the defaults.

2. the development of a diagnosis methodology containing the unification of the various obtained data in order to provide reliable and realistic input parameters to the models and to obtain a good evaluation of their spatial variability.

2. the development of a model which incorporates the soil and structure variability and takes really their interaction into account. The model will be characteristic of the problem handled (underground structure, damaged state, urban area), it will be fed by the input parameters developed at the point 2. and will provide an estimation of the global state of the structure portion.

3. the development of a basic tool to decision aid and risk analysis for the choice of a strategy of maintenance.

Majors Résults of the projet :
• The improvement of the current methodologies of diagnosis (in particular of the state of masonries) by means of the coupled use by the géoendoscopy and by the radar geophysics.
• A better estimation of the soils modulus from the penetration test.
• A realistic consideration in the numerical models of the interaction soil / structure by integrating the variability of the data.

The Méditoss project is an industrial research project manged by the Institut Pascal (Pierre BREUL). Four partners are involved in this project: two public laboratories (Institut Pascal - Université Blaise Pascal and LGCIE of INSA de Lyon) and two industrial partners (RATP and Sol Solution).

National conferences :
D. Llanca, P. Breul, A. Talon, C. Bacconnet, M. Sahli, Y. Haddani - Caractérisation de l’état de la maçonnerie d’un ouvrage enterré, 29èmes Rencontres de l’AUGC - 29, 30 et 31 Mai 2011 Tlemcen, Algérie

T. Kamel, F.L. Pellet, C. Silvani, P. Goirand et F. Emeriault - Modélisation numérique de la dégradation au cours du temps des propriétés mécaniques du revêtement d’une galerie de métro - Journées Nationales de Géotechnique et de Géologie de l’ingénieur – 4/6 Juillet 2012, Bordeaux

International conferences :
D. LLanca, P. Breul, A. Talon, Y. Haddani, C. Bacconnet, P. Goirand, L. Leuliet - Caractérisation des composants d'un ouvrage enterre en service, en vue de l’évaluation de son état, Congrès International AFTES: Espaces souterrains de demain, 17/19 Octobre 2011 – Lyon.

T. Kamel, F.L. Pellet, C. Silvani, P. Goirand et F. Emeriault - Numerical modeling of the time dependent degradation of the mechanical properties of a metro underground gallery, 1st Eastern European Tunnelling Conference – Budapest 2012

The infrastructure maintenance is of major concern for the management and the development of cities, in order to ensure good working conditions, security and to optimize the management cost of these structures. It is thus essential that the managers can improve their diagnosis techniques and have the adequate tools to better assess the current state of their structures. However, the methods that they currently have at their disposal are either deficient to give quantitative information of good quality or not adapted to the site constrains, especially for underground structures in use. This project proposes to develop a new diagnosis methodology for this type of structures and a tool for the study of their behaviour that better takes the various components and their interaction into account. The aim is to provide physical and mechanical indicators to managers in order to help them defining their maintenance policy, based on a more rational expertise. The application areas of this project are the infrastructures and the underground networks. The project consists of four parts: comparative experimental study, diagnosis methodology and data processing, modelling methodology, decision aid/risk analysis. The duration of the project would be 4 years with a total cost equal to 976,2 k' including solicited aid of 611,8 k'. The purpose of task 1 is to measure and evaluate the current state of the various components of the structure. Therefore, a set of monitoring tools adapted to the site constrains will be tested and the processing of some tools under development will be ameliorated. The proposed diagnosis methodology contains the unification of the various obtained data in order to provide input parameters for reliable and realistic models (task 2). Moreover, the data analysis methods should permit a good evaluation of their spatial variability. The development of a model which incorporates the soil and structure variability and takes really their interaction into account is planned during this project (task 3). The model will be characteristic of the problem handled (underground structure, damaged state, urban area) and will lean on existing modelling and/or modelling under development (discrete element modelling, coupling with a continuum modelling). This model will evaluate the global state of the structure portion and will be used as a basic tool to decision aid and risk analysis (task 4). For RATP, the expected spin-off in industrial and operational points of view are the validation of monitoring techniques that appears not very invasive and able to provide a rapid and reliable diagnosis, the development of tools giving an estimation of the current state of the monitored structures and the development of a diagnosis and decision aid methodology more rational and leading to less nuisances. This project would help the Sol Solution company to develop and optimize its tools and methods of diagnosis for the structures in use, in order to extend its panel of services. In a scientific point of view, the fall-out concerns mainly the improvement of the knowledge on the in-situ measurement tools for the material identification and on the methodology to unify results coming from various tests, in order to provide more relevant input data to models. Four partners are involved in this project: two public laboratories (LaMI of Université Blaise Pascal and LGCIE of INSA de Lyon) and two industrial partners (RATP and Sol Solution). The project is driven by the LaMI. The team of LaMI is specialized in the study and the characterization of surface soils and granular materials by the development of in-situ measurement tools, the development of techniques to process experimental data, methodologies to diagnose structure and methods to analyse risks. LaMI will manage tasks 2 and 4. The team of LGCIE is specialized in soil-structure interaction problems, dealt by observation, in-situ or laboratory experimentations and numerical modelling. The two main areas of interest are the urban underground structures in interaction with their surrounding and the mechanical behaviour of reinforced ground. LGCIE will drive the task 3. RATP owns, maintains and develops an important number of galleries and tunnels. Thus RATP performs inspections and controls, programs repairing and renovations of its infrastructures and instructs internal projects. Within these activities, RATP has got great expertise and experience in the maintenance and diagnosis and owns a large number of experimental data. RATP will drive task 1. The Sol Solution company develops and implements easy, economical and reliable solutions for the geotechnical characterization of shallow soils. It is specialized in the structure diagnosis, more particularly for underground structures. This partnership thus has an adequate structuring concerning the project objectives, as the various partners have transversal competences and complementary interests.