Influence Factors and Sensitivity Analysis of Mechanical Properties of Deep Foundation Pit Occluding Pile

Excavating foundation pits in mud-filled marine strata often leads to serious deformation of the enclosure structures, resulting in instability or collapse of the pits. This paper, based on the engineering project of a metro open cut section in Shenzhen’s mud-filled marine strata, utilizes Lizheng software to simulate the entire excavation process of a deep foundation pit. The model’s accuracy is verified through a comparison between the field-measured data and the simulation results. Subsequently, an analysis is conducted on the influencing factors of the enclosure structure’s mechanical properties using interlocking piles, coupled with an orthogonal test to analyze its sensitivity. The findings reveal: (1) The depth of enclosure structure embedment is significantly related to the deformation and stress characteristics of the enclosure structure; (2) The minimal deformation and stress of the enclosure structure occur when the following conditions are met: surface overload of 15 kPa, external water level of 7 m, concrete strength of C35 for the enclosure structure, an embedment depth of 10 m, and both the cohesion and internal friction angle of the soil being 1.2 times their original values (the optimal combination being Ⅰ₁Ⅱ₃Ⅲ₂Ⅳ₃Ⅴ₃Ⅵ₃); (3) The major influencing factors on the horizontal displacement and bending moment of the pit enclosure structure are the soil’s internal friction angle and the embedment depth of the enclosure structure respectively.