Three-dimensional finite-element analysis of panel installation of a ultra-deep diaphragm wall

It is well known that installation of diaphragm walls in heavily overconsolidated soils will cause substantial ground deformation and can influence the behaviour of the wall during the main excavation process. However, it has not been considered that the installation effect of the panels of ultra-deep diaphragm wall in normally consolidated soils. A popular commecial finite element software, ABAQUS, is employed to simulate the panel installation process of a ultra-deep diaphragm wall in normally consolidated clay. The clay plasticity soil model in ABAQUS, which is based on the modified Cam clay model, is selected to simulate the clay characteristic. The physical meanings of the parameters for the clay model in ABAQUS are discussed, and the methods to decide the parameter values from triaxial compression tests or oedometer tests are presented. A formula for the initial void ratio and the mean effective stress in the field is deduced and used in the simulating by ABAQUS. Three-dimensional numerical models are established to simulate the installation process of the panels, including excavation under a bentonite support, placing and subsequent hardening of concrete. The deformation characteristics of the soil layers induced by the construction of wall panels as well as the influences from the width of the wall panels and the weight of the bentonite slurry are studied.