To determine the distribution of the active earth pressure of the cohesionless soil under the rigid retaining wall rotating around the base (i.e.

RB) mode

the discrete element simulations concerning different post-fill widths were carried out. The simulation results show that the active earth pressure distribution in the RB mode is different from the parabolic distribution of the active earth pressure in the translation (T) mode. When the soil behind the wall is in an active limit state

multiple parallel slip lines are formed inside the soil. An oblique differential element method based on slicing of slip line is proposed based on the numerical results. Based on the proposed method

the soil behind the wall is divided into several oblique differential elements

and the theoretical formula of active earth pressure under RB mode is derived according to the static equilibrium condition. In the case of infinite soils

the theoretical formula is consistent with the Coulomb's active earth pressure formula of triangular distribution. In the case of finite soils

the active earth pressure is piecewise linear distribution along with the depth. In the case of wall soil without friction

the theoretical formula will degenerate into Rankine's active earth pressure formula. Finally

the rationality and effectiveness of the theoretical formula are verified by comparing with the results of discrete element simulation

previous theoretical methods

and model tests.