Use two- and three-dimensional models to assess the stability of trench walls for underground construction in sand and sandy silty clay, supported by bentonite suspension

Tóm tắt

A trench excavation is the first step in the underground wall construction process. Today, the technique of excavating trenches supported by bentonite suspension to prevent collapse and ensure trench stability has become common in many countries worldwide. Following this trend, this article applies the technique to a typical stratum in Hue City, Vietnam. Simultaneously, the study utilizes the Finite Element Method (FEM) with the RS software program and the Finite Difference Method (FDM) with the FLAC software program. Additionally, the Shear Strength Reduction (SSR) technique and the Mohr-Coulomb material model are employed to develop 2D and 3D models and analyze the stability of the bentonite suspension trench. The analysis is conducted under a scenario where no surcharge load is applied on the ground surface, and the surface is not reinforced with a concrete layer. The trench dimensions are 1 m in width, 6 m in length, and 10 m in depth, the densities of the bentonite suspensions are 10.5 kN/m³ and 12 kN/m³, with the level of bentonite suspension in the trench maintained equal to the ground surface level. The obtained results are as follows: (1) An evaluation of the safety factor of the bentonite suspension trench under the specified scenario; (2) A prediction of the influenced zone caused by the excavation of the bentonite suspension trench. Determining the influenced zone caused by trench excavation is closely related to the safety of neighboring structures near the excavation trench. Structures located outside the influenced zone are considered safe