Mechanical Response Analysis on Construction of Diaphragm Wall in PBA Underground Excavation Subway Station

Based on the first underground diaphragm wall water stop project constructed in the side pilot tunnel of PBA underground excavation station of urban subway in China, MIDAS software was used to analyze the mechanical performance of underground diaphragm wall in the construction process of PBA underground station, and the results were compared with the actual field monitoring data. The results show that: (1) during the whole construction process of the station, the surface settlement caused by diaphragm wall construction is small, accounting for about 9% of the total surface settlement. (2) The horizontal displacement of diaphragm wall changes greatly in the construction stage of buckle arch, the excavation and support stage of station hall and platform layer. In practical engineering, these three construction stages need to strengthen the control and monitoring. (3) In each construction stage of the station, the vertical displacement of diaphragm wall is mainly uplift deformation, and the settlement deformation is not obvious. Along the longitudinal distribution of diaphragm wall, the settlement of the top of the wall fluctuates slightly in each construction stage, and tends to be evenly distributed on the whole. (4) After the construction of the main structure of the station, the tensile and compressive stress of the diaphragm wall does not exceed the allowable value of the compressive and tensile strength of the concrete, which can effectively ensure the safety performance of the diaphragm wall itself.