| The classical earth pressure theory is only applicable to the case of shear damage of soil when the displacement of retaining wall is large enough,while in practical engineering,due to the strict deformation control requirements of retaining wall,the soil behind the wall often cannot reach the ultimate equilibrium state,i.e.,it is in the non-limit state,so it is necessary to carry out corresponding research on the non-limit earth pressure on retaining wall to guide the engineering practice.In this paper,the problem of non-limit active soil pressure on sand during active movement of rigid retaining wall is addressed,and discrete element simulation of soil active damage process under different movement modes of retaining wall is carried out,based on the simulation results,the change law of soil pressure,change law of wall-soil friction angle,soil damage process and change of soil internal stress state under different movement modes are analyzed,and the corresponding theoretical research is carried out on this basis.The main results are as follows:（1）The simulation study of non-limit active earth pressure problem in sandy soil under RB mode,T mode and RT mode was carried out by using discrete element software PFC2D,and the change law of resultant force,earth pressure distribution and earth pressure strength at different depths of retaining wall with the displacement of retaining wall under three displacement modes was analyzed;the situation of internal sliding zone of soil behind the wall was observed,and the failure process of the soil under three movement modes was analyzed;the friction angle mobilization law and the deflection of the principal stress within the soil during the active movement of the retaining wall are analyzed.（2）Based on the discrete element simulation results under RB mode,the law of the internal friction angle mobilization and the law of wall-soil friction angle mobilization are modified.The oblique differential element method,which is more in line with the characteristics of soil failure in RB mode,is adopted to derive the non-limit active earth pressure calculation formula of retaining wall in RB mode.Finally,the theoretical calculation results are compared with the measured data of the model test to verify the rationality of the calculation method.（3）Aiming at the problem of non-limit active earth pressure calculation under T mode,the calculation formula of non-limiting active earth pressure in T mode is obtained by using the horizontal differential element method on the basis of the modification of the law of the internal friction angle and the wall-soil friction angle,assuming that the soil slip surface in T mode is straight and the trajectory of minor principal stress is parabolic.（4）For the calculation of non-limit active earth pressure in RT mode,the law of the internal friction angle and wall-soil friction angle are modified.On this basis,the arc-shaped minor principal stress trajectory is used to describe the phenomenon that the principal stress deflection angle in the upper part of the soil behind the wall is large.And assuming that the slip surface is a quadratic parabola,the calculation formula of non-limit active earth pressure in RT mode is derived by using the horizontal differential element method,and the rationality of the calculation formula is verified by comparing the measured data. |
