Analysis Method Of Earth Pressure On Retaining Wall Based On Simplified Principal Stress Trajectory

The earth pressure of retaining wall is the result of the interaction between the back of retaining wall and soil mass.The research on its calculation theory and method began in the 18 th century.Up to now,the most classical and widely used theories are still Rankine earth pressure theory and Coulomb earth pressure theory.However,neither of the two classical earth pressure theories can consider the influence of the deflection of the principal stress direction in soil behind retaining wall caused by the development of friction angle of wall soil contact surface on earth pressure,and the horizontal layer analysis method commonly adopted by most scholars needs to make various assumptions about the stress distrib ution on the interface of horizontal thin-layer unit,which is unreasonable.Therefore,it is of great significance to carry out research on the calculation method of earth pressure of retaining wall,which can not only consider the influence of the degree of wall-soil friction,but also reasonably divide the thin-layer units of the soil mass and reasonably analyze the stress of the thin-layer units.In this paper,the failure mode of backfill behind the retaining wall is analyzed in detail firstly,and the mechanism of soil arching effect is summarized.The circular principal stress trajectory is selected to describe the transfer law of principal stress in sliding soil wedge combined with the transfer characteristics of principal stress in soil.According to the deflection of the principal stress trajectory at the wall-soil contact surface and the slip surface in the soil,the circular principal stress trajectory are approximated as a straight line by three different simplified methods,and the theoretical formula of the principal stress deflection angle of the linear soil arch is derived.On this basis,the sliding wedge is layered along the direction of the resulting simplified inclined linear principal stress trajectory,so the tilted straight-line layered method of backfill behind retaining wall is proposed to optimize the horizontal thin-layer analysis method.Then,the inclined linear thin-layer element obtained by tilted straight-line layered method is taken as the research object of stress analysis,and the stress distribution of backfill behind the wall is considered meeting the characteristics of the gravity field.It is assumed that the numerical value of the principal stress on the interface of stratification varies linearly with the depth,so the a ssumption of principal stress distribution on the layered interface is given.Based on the equilibrium limit conditions of the inclined linear thin-layer element and the boundary condition,a new method for analyzing the active and passive earth pressure of a translational rigid retaining wall considering the effects of wall-soil friction and wall back inclination is proposed.Through the comparative analysis with the test,the rationality and feasibility of the calculation method of the ultimate active and passive earth pressure of retaining wall established in this paper are verified,and the applicability for the retaining wall of different heights is also verified.Through sensitivity analysis,the variation law of earth pressure of retaining wall with engineering reference value is obtained.Nest,based on the analysis method of earth pressure in limit state,a new method for analyzing the non-limit active and passive earth pressure of retaining wall considering the soil arching effect is proposed,by di scussing the variation law between the internal friction angle and wall-soil friction angle and the translational displacement of retaining wall.Through the comparative analysis with the test results,it can be seen that in the process of the lateral disp lacement of retaining wall gradually increasing from zero,the non-limit active and passive earth pressure distribution curve in this paper is consistent with the change law of the measured result,which proves the rationality of the calculation method in this paper.Finally,considering the influence of earthquake,the pseudo-static method is used to treat the seismic force as a static force acting on the sliding wedge.Based on the equilibrium condition of the inclined linear thin-layer element and the boundary conditions,the active and passive earth pressure analysis method of retaining wall considering the effect of soil arching and earthquake action is proposed.The sensitivity analysis of the influence of horizontal and vertical seismic effects on the earth pressure distribution of retaining wall is carried out,and the relevant laws are summarized,which can provide some reference for seisic design of retaining wall.