An Analysis Of Earth Pressure Against Retaining Wall Of Soil With Finite Width Based On Principal Stress Trajectory

The calculation of earth pressure is the important base of the design of retaining wall and other supporting structures.And it is the key to select the type of supporting structure,classify strength grade and cost of construction.Now with the problem of retaining wall with finite soil is becoming more and more common.Therefore,it is of great theoretical significance and engineering application value to deeply study the calculation of earth pressure influenced by the factors such as the width of backfill.First,this paper summarizes and analyzes the existing theories of calculating earth pressures with finite soil,aiming at the deficiencies of the vertical stress and horizontal shear stress of rectangular differential flat element.considering the friction between retaining wall and soil will inevitably lead to the deflection of principle stress direction in soil behind retaining wall,and basing on the concept of principal stress trajectory,this paper deeply and respectively discusses the geometric parameters of principal stress trajectory in soil behind retaining wall under active and passive state.Then obtaining the deflection law of principal stress of principal stress trajectory with the equation of principal stress trajectory,and the deflection law of the principal stress direction of each point of the soil is deduced.According to the relationship between the principal stress of each point and the normal stress and the shear stress of any section,the actual value and distribution of the vertical stress and the horizontal shear stress on the surface of the rectangular differential flat element are obtained.On this basis,the force analysis method of the rectangular differential flat element is improved,and the relative static equilibrium equation of the mlement is perfected,finally the calculation and analysis method of retaining wall with finite soil based on the principal stress trajectory is established.In the end,the rationality and feasibility of the method proposed in this paper have been demonstrated by comparing with the existing theory and related experiment.Under active state,the earth pressure with finite soil width grows in nonlinear and the growth rate decreases with the increase of depth,the position of force point is higher than that of Rankine theory.Under passive state,the earth pressure with finite soil width grows in nonlinear and the growth rate increases with the increase of depth,while the position of force point is lower than that of Rankine theory.What's more,this paper discusses the influence of different width to height ratios,different friction angles of wall-soil on the distribution of earth pressure.