Earth Pressures on Underground Structures in Long Vertical Trenches With Heterogeneous and Nonlinear Soil Backfills Using a Slice‐Based Numerical Approach

ABSTRACT The earth pressures on underground structures in trenches are typically evaluated using the conventional Mohr‐Coulomb (MC) yield criterion under the assumption of homogeneous soil backfills. However, most geomaterials are inherently heterogeneous and exhibit nonlinear shear strength characteristics. In this research, a novel slice‐based numerical solution procedure based on the limit equilibrium method of horizontal slices is developed to evaluate the earth pressure distribution in long vertical trenches backfilled with heterogeneous soils exhibiting nonlinear shear strength. The analysis is carried out under plane strain conditions and employs the nonlinear power‐law (PL) yield criterion together with linearly varying soil parameters to account for the nonlinear and heterogeneous characteristics of the soil backfill. The variations of vertical earth pressure () with depth () below the ground surface for homogeneous clay and sand trench backfills, evaluated using both the MC and PL yield criteria, reveal the significance of shear strength nonlinearity. A detailed parametric investigation is further conducted to examine the effects of different parameters on the variation of the curves. The computations demonstrate that the combined effects of soil nonlinearity, heterogeneity, and arching significantly affect both the magnitude and distribution of earth pressures within the trench. Moreover, the proposed procedure yields results that show excellent agreement with those reported in the existing literature based on the MC yield criterion.