Abstract: In the design and calculation of the excavation engineering, the influence depth of unloading is usually determined based on experiences. In this work, a large number of unloading stress path experiments are performed to simulate the stress propagation process in the passive zone at the bottom of the foundation pit. Vertical deformation and the change in the horizontal stress are analyzed. The method for estimating the unloading depth in the excavation engineering is presented by analyzing relationship between the unloading ratio and the rebound strain and horizontal stress. The result is useful in excavation engineering.

Key words: influence depth of unloading, static earth pressure coefficient, unloading ratio, excavation