Analysis of the behaviour of propped diaphragm walls in a deep clay deposit

Modern techniques of excavation, including the use of structural diaphragm walls and top-down construction, provide effective methods to minimize deformations in the surrounding soil. However, for deep excavations and walls embedded in deep layers of soft clays, it is difficult to control soil movements. In these situations, reliable predictions of deformations are an important consideration in the design of the earth support system. This paper describes results of numerical experiments, based on non-linear finite element analyses and incorporating an effective stress soil model which describes observed aspects of soft clay behaviour including small strain non-linearity and anisotropic stress-strain-strength. The analyses consider the undrained deformations around a braced diaphragm wall in a soft clay deposit. Principal parameters considered in the study are the wall embedment depth and support spacing. A simplified framework is developed to interpret wall deflections and ground movements with excavation depth. -Authors