DEM Analysis And Simplified Calculation Of Active Earth Pressure On Retaining Walls Of Narrow Backfill Width

With the rapid development of urban engineering construction,the building density is increasing.In dense urban areas,a large number of retaining walls must be close to the existing solid wall(rock wall)or the construction of existing underground outdoor walls.In this case,the space behind the wall filling will be limited.However,current conventional earth pressure calculation theories,such as the Rankine pressure theory and the Coulomb earth pressure theory,are based on the assumption of semi-infinite width soil,and it is difficult to consider the influence of the fill width of the wall.Therefore,in this case,the failure mode of the soil behind the wall and the calculation method of the active earth pressure are studied in-depth for the engineering application.The main work is as follows:Firstly,to sum up the previous research results of earth pressure calculation methods,and focuses on two typical methods of calculating soil pressure behind a finite width soil;namely limit analysis method and limit equilibrium method,and analyzes the advantages and disadvantages of the two methods.Secondly,Based on the non-sticky finite-width fill behind the wall,the Discrete Element Method(DEM)was used and the PFC2 D software was used to establish a numerical model for non-cohesive soil with three modes of rotation of the retaining wall around the bottom of the wall,rotation around the top of the wall and translation.On this basis,the failure modes of the backfill of the retaining wall under the three modes were obtained,and the shape of the sliding surface and the failure law of the soil after the wall with different widths and different internal friction angles were obtained.Compared with the existing experimental data,the comparison results prove the reliability of the numerical simulation in this paper.Thirdly,based on the obtained limited-soil soil sliding surface behind the wall,the soil sliding body is regarded as a trapezoidal destruction body,which is divided into two parts,a rectangle and a triangular slider,and based on the thin-layer element method and the limit equilibrium respectively.The method obtains the expression of the active earth pressure and the position of the resultant force.Based on this,an active earth pressure calculation method for a finite-width soil behind a wall was established.The comparison between the calculated value of this method and the experimental data of the literature shows that the calculated value of the method is in good agreement with the experimental data and has practicality.In addition,This paper also discusses the influence of the main parameters such as the width of the filling and the internal friction angle of the filling on the distribution of the active earth pressure and the resultant force,for the reference of the engineering design.