Deformation rules of deep foundation pit of a subway station in Lanzhou collapsible loess stratum

Abstract

According to the deep foundation pit project of Xiaoxihu station on Lanzhou subway Line 1, the three-dimensional finite-element model of the half-cover excavation method of retaining structure is established to simulate the construction of the excavation of the foundation pit. This article analyzes the settling of the surrounding surface, the horizontal displacement and vertical displacement of the retaining pile, the vertical displacement of the shoring column, and the change of the axial force of the inner support and compares them with the actual monitoring data. The results show that for the collapsible loess strata in Lanzhou, the design of retaining pile and inner support is viable. The support form has a good control effect on the deformation of the foundation pit. It keeps the foundation pit stable. The numerical simulation results are more consistent with the actual monitoring data. It provides a basis for the scientific design and construction of a deep foundation pit in the Lanzhou metro station.

Keywords

• deep foundation pit
• three-dimensional finite element
• collapsible loess
• inner support
• pile displacement