Abstract: The stress concentration in diaphragm wall support system, combined with an intolerable difference between deformation of diaphragm wall occurred during the construction process and predicted by design probably result in large construction risk. The paper solved these problems by model tests in which an adjustable device was set on the support system. The compatible deformation among the support system, the diaphragm wall and the ground soil behind the diaphragm wall were investigated. The variation of the support axial force, the lateral earth pressure on the diaphragm wall, the ground surface settlement around the foundation pit and the maximum deformation of the diaphragm wall with the adjustment mode of supports were obtained. A smart regulation method for compatible deformation of the diaphragm wall support system was proposed. The results show that under a constant displacement condition, the variation of support axial force caused by the adjustment of the upper support is the largest, by the adjustment of the bottom support is secondary, and by the simultaneous adjustment of the four supports is the smallest. However, the influence range of the ground surface displacement increases with the depth of the adjusted support, but the amplitude decreases. The influence range and amplitude of the simultaneous adjustment of the four supports are larger than that of the adjustment of a single support. The lateral displacement of the diaphragm wall can be reduced by the extension of the support, but the axial force of the support will increase sharply. It can be concluded that it is not wise to strictly control the horizontal displacement of foundation pit. Instead, a reasonable adjusted displacement of support and the monitoring of the support axial force and displacement in succession are recommend.

Key words: deep foundation pit, support system, compatible deformation, model test