Study on Stability and Deformation Characteristics of Ultra-Deep Diaphragm Wall during Trench Excavation

Abstract

The stability and deformation during trenching of ultra-deep diaphragm walls have a greater impact on the construction of diaphragm walls. The conventional limit equilibrium method, known as the vertical slices method, assumes homogeneity within the rock and soil mass, making it challenging to account for their stratification. Based on the limit equilibrium method, the horizontal strip method takes into account the stratification of the foundation soil. Based on the actual project, considering the different mud unit weights and heights, the horizontal strip method was used to analyze the stability of the groove trench and analyze the deformation law of the groove trench by the finite element method. The results indicate the following: The horizontal strip method can effectively assess the influence law of mud weight and height on the safety coefficient of groove trench stabilization. The higher the unit weight and level of slurry, the greater the wall safety coefficient. Moreover, the mud unit weight obtained by the horizontal strip method is about 12.70~12.64 kN/m3, which is close to the actual maximum mud weight of 12.5 kN/m3. The estimated mud unit weight aligns more closely with actual conditions. Additionally, through finite element analysis, the deformation law of the groove trench of ultra-deep diaphragm walls has been analyzed and summarized. The soil around the groove trench does not move inward, which shows three different deformation modes with different depths.