EXPERIMENTAL STUDY ON DEFORMATION AND INSTABILITY OF FOUNDATION-PIT IN SOFT SOIL

Model experiment on excavation of foundation pit in soft soil with different properties was conducted at different ground water condition. The experiment reveals that in braced or softly braced excavation of pit, the wall develops a relative large deformation before instability occurs. It also shows that the failure plane, which can be fitted with a parabola equation, is different from the usually supposed circular plane; the influence of seepage destruction of the wall on ground subsidence is much serious than that of lateral deflection of the wall. It is essential to consider the mechanical strength of soil in analyzing the base heave caused by the confined ground water, otherwise, the calculated result is unreasonable to some degree.