Abstract: This study investigates the distribution of non-limit active earth pressure in sand under the rotation around the base and translation coupling (RBT) mode of rigid retaining wall. Three groups of position parameter of rotation center (n=0.5, 1.0, and 5.0) are selected for discrete element simulation study. The results indicate that the active earth pressure in RBT mode exhibits both concave distribution characteristics of the rotation around base (RB) mode and linear distribution characteristics of the translational (T) mode in rigid retaining walls. During failure, the wall-soil friction angle usually reaches its limit value before the internal friction angle. The slip surface behind the wall forms a curve, with a noticeable principal stress deflection at the soil slip surface. Based on the numerical simulation results, the relationship between the equivalent internal friction angle of the interlayer and the position parameter of rotation center n is derived using the middle symmetrical arc arch. The force equilibrium equation for the curved trapezoidal differential unit is established using the horizontal layer analysis method, and the numerical solution for non-limit active earth pressure in RBT mode is obtained using the finite difference method. Parameter analysis shows that displacement, internal friction angle and n significantly affect the active earth pressure. Comparison of numerical simulations and model tests verifies the rationality and reliability of the theory presented in this paper. The findings provide a valuable reference for calculating earth pressure in rigid retaining walls.

Key words: RBT mode, non-ultimate active earth pressure, discrete element method, soil arching effect, equivalent internal friction angle of interlayer, horizontal layer analysis method