Research on Influence laws of Approaching Excavation on Stress and Deformation of a Pier

  • Shuai Huang, Jian Li, Ben Mou, Shufeng Zhai, Shijie Li

Abstract

Along with the accelerating development of urban rail transit engineering, subway construction near the existing overpasses has become a common practice. However, the new construction activities have an inevitable impact on the existing bridge structures. In the present paper, the renovation of a highway overpass on the south side of Hongxing Road, Tianjin, is taken as the engineering background against which the simulation modeling is conducted. Approaching excavation of the foundation pit is undertaken for the construction of a new pier adjacent to an existing pier. We discuss the influence of the approaching excavation on the existing pier. Numerical simulation is performed for the excavation process of the foundation pit. The influence of the approaching excavation on the existing pier is evaluated by simulation calculation. The calculation results show that as the excavation depth increases, the pier subsidence gradually increases. Under approaching excavation, the pier undergoes inclination and subsidence. The support structure is considerably deformed due to squeezing by the continuous wall. The upper layer of support is deformed insignificantly, presenting with a downward bending. The lower layer of support is deformed more significantly, presenting with an upward bending. The soil at the bottom of the foundation pit rebounds after unloading, resulting in an eminence. The retaining walls of the foundation pit and the supports are subject to the squeezing and thrust action due to the additional stress imposed by the soil at the bottom of the pier. As a consequence, the lateral bracing closer to the pier is deformed more dramatically. Our research findings shed new light on the design and construction of a new pier adjacent to an existing pier.

Keywords- Foundation pit, approaching excavation, pier, support structure, subsidence

Published
2021-06-24
Section
Articles