An Approach To Determining Lateral Pressure Considering The Decay In Permeability Coefficient With Depth And Application To The Subsea Tunnel Of Xiamen Metro Line 2

The determination of lateral pressure on a tunnel face is a paramount concern during the process of replacing cutting tools for a subsea shield tunnel. In conventional methods for the calculation of lateral pressure, the influence of soil permeability has seldom been considered, and the decay in permeability coefficient with depth has been ignored. In this article, an approach for determining the lateral pressure considering the decay in permeability coefficient with depth is put forward. Based on the previous method considering constant permeability coefficient, two different types of decay mode are considered in the proposed approach. For the linear type, the explicit expressions of the resultant thrust are then derived and set up. For the negative exponential type, a numerical method is needed to calculate the lateral pressure. Then the proposed approach is applied to the Subsea Tunnel of Xiamen Metro Line 2. Based on the results of the application, the linear type is recommended for use in considering the decay in soil permeability coefficient with depth, and the corresponding explicit expressions are recommended for calculation of the lateral pressure in engineering practice.