Three-dimensional calculation method on local slurry wall stability of diaphragm wall trench based on minimum potential energy principle

Because the soft weak soil layer rich in confined groundwater is prone to local instability and failure in the construction of diaphragm wall trenches, in order to check the local slurry wall stability in the construction of diaphragm wall trenches, a new three-dimensional (3D) calculation method on the local stability safety factor (LSF) of slurry walls is proposed based on the minimum potential energy principle. After the new method is applied to two engineering cases, the value of the LSF solved is 0.82 for engineering case 1, and the values of the LSF solved are 0.84 and 1.05 when the phreatic water levels are 2 and 4.5 m, respectively, for engineering case 2. These results are very close to the calculation results in the existing references, so the rationality of the new method is verified. Then the sensitivity of the LSFs obtained from the new method to various parameters has been analyzed and clarified on the basis of ten design examples. Finally, the new method is used to check the local slurry wall stability in the construction of diaphragm wall trenches for a practical project, and the obtained values of the LSF for three concerned weak soil layers are 1.37, 1.19, and 0.82, respectively. These results are in agreement with the actual situation in the construction site. This reveals that both the 3D model established and the 3D calculation method proposed in this paper are suitable for application in practical projects.