THE EFFECT ON PROPPED DIAPHRAGM WALLS OF RISING GROUNDWATER IN STIFF CLAY

The Paper investigates the stability and service-ability of propped diaphragm walls constructed in situ in stiff clay, first when an excavation is formed in front, second when the groundwater level recovers, and third when it is raised. Three centrifuge model tests were conducted to observe the behaviour of these structures. Simplified behavioural mechanisms are shown to provide a method of analysis for a propped diaphragm wall which would permit a designer to calculate the soil and structural deformations without recourse to expensive and complicated computer-based analyses. The essential conditions are the satisfaction of equilibrium and compatibility requirements, and the ability to use stress-path specific stress-strain data. Where there was little structural displacement, the earth pressures were calculated using a bilinear approximation to the measured stress path of kaolin in one-dimensional swelling.