Active Earth Pressure of Finite Width Soil Considering Intermediate Principal Stress and Soil Arching Effects

Traditional earth pressure theories are based on the assumption of semi-infinite space. The existence of intermediate principal stress and soil arching effects is ignored, which will cause significant errors in the application of finite width soil. This study introduced the intermediate principal stress based on the twin-shear unified strength theory; the stress deflection caused by soil arching and the uniform surcharge on the retained soil surface were also considered. An improved calculation method for cohesive soil's lateral earth pressure coefficient, an analytical solution for active earth pressure of finite width soil, the resultant force, and its action point were proposed. The lateral earth pressure distribution of finite width cohesive soil was studied by calculation examples. In addition, relevant parameters were also analyzed. The results indicate that due to the influence of the intermediate principal stress and soil arching effects, the resultant active earth pressure is lower than the traditional method. The lateral earth pressure coefficient gradually increases with the depth, but it is always lower than the traditional one. As the soil width increases, the resultant force action point presents a nonlinear trend that first decreases, then rises, and stabilizes. The proposed method was compared with the previous studies and got better results; it can provide a new idea for estimating the active earth pressure of finite width soil.