Statistical Analysis of Deformation Laws of Deep Foundation Pits in Collapsible Loess

To define the deformation of time and space during the construction of a long and deep foundation pit in collapsible loess, the field-measured data of 10 open excavation stations in Xi'an metro are analyzed statistically. The results indicate that the vertical deformation of the ground and the lateral deformation of the soldier pile caused by the excavation of a long and deep foundation pit in collapsible loess increase with time. The maximum surface subsidence decreases with the increase in stiffness (K) of the foundation pit support system, increases linearly with the excavation depth (H_w), and decreases with the increase in the aspect ratio of the foundation pit. The lateral maximum deformation value of the soldier pile decreases linearly with the increase in insertion ratio and decreases with the increase in K of the support system. The surface subsidence of the foundation pit is characterized by a "groove shape", and the deformation of the soldier pile is characterized as the "medium convex". These results can provide a reference for the design and construction of similar projects in loess areas, and can predict and evaluate the deformation size and safety of similar projects, which is of great significance for further understanding the deformation mechanism of deep foundation pits in loess areas, thus perfecting the design theory and preventing foundation pit accidents.