Microstructural Mechanism of Long-Term Deformation of Soft Clay Relating to Time and Cyclic Loading Effects

par Dan Wang (Zhao)

Projet de thèse en Génie civil

Sous la direction de Mahdia Hattab et de Zhenyu Yin.

Thèses en préparation à l'Université de Lorraine , dans le cadre de EMMA - Ecole Doctorale Energie - Mécanique - Matériaux depuis le 01-10-2014 .

  • Résumé

    Abstract: Soft clay is widely distributed in the world, with the rapid development of urbanization, design and construction of infrastructure on soft soil deposits is increasing in the past decades. Engineering design on soft deposit is still a challenge owing to its low bearing capacity, long-term deformation instability and the very complex stress-strain behavior. A lot of research and practice has proved that the engineering properties of soil are closely related to its micro-structural factors, which play a domination and control rule, in addition to its composition and distribution. The complexity and randomness of soft soil’s micro-structure leads to the complexity of its macroscopic mechanical properties, the existing conventional tests and macro research methods provide a “fitting” analysis of the characteristics of soft soil, which cannot predict its engineering properties accurately for a lack of understanding on the determine factors of soft soil. Research on microstructural mechanism of soil aims at: explain the origin of some engineering properties qualitatively based on the results, which is the main content of the present study; combine the macroscopic properties with the mathematical processing of microstructure research to estimate and forecast the range and trend of soil properties. Researches on micromechanics deformation of soil under different stress levels, frequencies, and loading paths will be developed, the research objectives are: to investigate the connections between the deformation of soil structure at different scales and the micromechanical behavior of remolded kaolinite samples by triaxial tests, oedometer tests and scanning electron microscopy (SEM); to develop a micromechanical coupling model to simulate the long-term deformation of soft clay, to propose the predicted deformation trends of soft soil from micro to macro under long-time loading .