Study On Limit Equilibrium Method Of Horizontal Slices For Earth Pressure On Rigid Retaining Walls Considering Shear Forces Between Adjacent Slices

Rigid retaining wall is a kind of retaining structure which widely used in engineering practice,and the earth pressure acting on the wall has always been a focus which influenced by many factors.This paper is dedicated to solve the ultimate earth pressure of rigid retaining wall considering two types of failure surface which including the straight and curved surfaces.A limit equilibrium method of horizontal slices for earth pressure on rigid retaining walls considering shear forces between adjacent slices is proposed.The unified analytical method of active and passive earth pressure integrates the structural type of retaining wall,properties of the filling behind the wall,external loads,and so on.The main results are as follows:（1）Based on the limit equilibrium theory,the computational model of the active and passive earth pressure established by the horizontal slice method which is used to calculate of potential sliding soil wedge completely satisfies the static equilibrium equation.Three value types ofλ,the key coefficient of shear strength between soil strips are discussed,and its empirical values are given based on a large number of test data.This paper also presents a search method to determine the plane and curved failure surface.The active and passive earth pressure under complex conditions is calculated by compiling Matlab program,and the distribution,resultant force and the position of action point of earth pressure can be determined.（2）The paper proposes that the soil-strip shear force is expressed by the coefficient of shear strength between soil strips.The coefficientλof the shear strength between soil strips can be regarded as a function of the wall height.The value of the coefficient is not equal 0 in most cases.Three assumed distribution modes are given,including inverse proportional function,linear function and sine function.In the active and passive limit states,the inverse proportional mode and sine mode are recommended.（3）In the active limit state,the value ofλdecreases to 0 with the decrease ofδ/φ;in the passive limit state,the value ofλincreases with the decrease ofδ/φ.In active state,the value is in the range of 10^-3-10^-2,and that of passive state is in the order of 10^-1.（4）In the active limit state,considering the coefficient of the soil-strip shear strength will make the position of action point of earth pressure closer to the measured value.The example analysis shows that the proximity has increased by 5.8%;in the passive limit state,considering the coefficient of the soil-strip shear strength will make the passive earth pressure significantly change.Applying the empirical value ofλsuggested in this paper,the concave degree of the earth pressure distribution curve and the sharp increase of the bottom end of the earth pressure are reduced.Comparing with the existing theoretical methods,this method can be close to the measured value by the greatest degree.（5）The example analysis shows that the active and passive earth pressures calculated by this method are in good agreement with the measured values and the values calculated by the existing theoretical methods.Specifically,comparing with the measured values,the average error of resultant force of active earth pressure is 4.5%,the average error of the position of action point of earth pressure is 10%,and the average error of resultant force of passive earth pressure is 3.6%.The unified calculation method for earth pressure on rigid retaining walls established in this paper can adapt to the changes of many influencing factors in actual engineering.It provides theoretical basis and reference for earth pressure calculation under complex conditions,and has important theoretical significance and engineering application value.