Conclusions and Prospects

Abstract

In this monograph, we took Shanghai muddy clay as the study object and analyzed the characteristics of soil dynamic response under subway loadings based on field monitoring of earth pressure and pore water pressure within soils. Benefiting from the field test, some basic parameters were obtained for the laboratory tests. A series of laboratory tests were conducted with a dynamic triaxial apparatus with unidirectional excitation combined with a multifunctional dynamic triaxial test system. The research focused on four main aspects: (1) the increasing law of pore water pressure of soft clay under subway load, (2) the relationship between dynamic stress and strain, (3) the law of strength degradation under dynamic loading, and (4) creep behavior under dynamic loading. In addition to the experimental study above, 3D finite element model was established to simulate dynamic response of soil surrounding the subway tunnel when the subway trains goes through. Besides the macroscopical study of the research object, the microstructure of soil was studied as well based on mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). The former one provides access to quantitatively analyze the microstructure of soft clay before and after vibration (such as variations of pore size distribution, pore quantity, and other microcosmic parameters), while the images of SEM provided visible and qualitative analysis of soil structure.