Seismic Earth Pressure Calculation Of Retaining Wall

As one of the most widely used special structure in engineering practice,retaining wall is largely used in road, bridge abutment, water conservancy and portengineering, industrial and civil engineering and railway engineering. Our country isone of the most severely affected countries by earthquake; it is located betweenCircum-Pacific seismic belt and Mediterranean-Himalayan seismic belt, which bothare the most active seismic belts in the world. Retaining wall’s destruction iswidespread in the earthquake. The destruction of the retaining wall causes damage toroads and bridges, which not only bringing traffic interruption, but also resulting greatdifficulties to relief work after earthquake and causing larger loss of life and property.As one of the hot topics of geotechnical engineering, seismic design of retaining wallattracts attention of scholars from various countries. To begin with Mononobe-Okabetheory, scholars from diffrent countries get a lot of meaningful results based onvarious assumptions. Quasi-static method regarding earthquake action as the inertialforce on the retaining wall, which turning the dynamic problem into static, is thecommonly used method in various countries’ code at this stage. These methods greatlysimplify the difficulty of the problem, and have accumulated rich experience inengineering practice, and it is easy to grasp for engineers.Firstly, the common types of retaining wall using in present project issummarizes in this paper. The selection of the type of retainning wall should take intofully account the topography, hydrology, geology, usage and construction methodsand other related factors of the engineering. And then a review of the history andcurrent status of research on calculation of seismic earth pressure on retaining wall athome and abroad was given to describe the further study significance on this topic.Basing on the horizontal slices analysis method, the non-cohesive soil’s seismicearth pressure is analyzed and then the angle of rupture is discussed under theassumption that the surface is flat. And when the filling soil surface existingoeverload, the seismic earth pressure is decomposed into three separate parts, whichare the pressure generated from the vertical seismic and its own weight, the pressuregenerated from the horizontal seismic earth pressure and the pressure generated by thesurface overload. Then the distribution pattern and the height effect point of the threeparts of pressure are discussed to lay the foundation for the study on cohesive soil retaining wall under earthquake.By regarding the cohesion as "inner structural pressure" of the wedge surround,it can transform the cohesive soil into non-cohesive. The only difference betweenthem is the boundary condition, but it can get a simplify solution of the seismic earthpressure of cohesive soils. The seismic earth pressure is now divided into four partsbecause of the cohesion, and the paper then discusses their law of distribution andaction position separately.Through the analysis of amplified curve, the cohesive and non-cohesive seismicearth pressure is explored in the paper under three typical seismic amplified curves.Finally through the variational principle, failure surface of the curves isdiscussed, and then by using the polynomial fitting, the paper gives a simplefunctional form of the curve. On this basis, this paper discusses seismic earth pressureof cohesive soil retaining wall under the assumption that the failure surface is a curveof parobala. And then by comparing the existing research, it can verify the reasonab-leness of the assumptions in the paper. The study conclusions in the paper have somereference value for the seismic design of retaining walls.