Computational Research And Analysis Of Active Earth Pressure For Limited Soil

With the continuous advancement of urbanization,new proposed buildings are often close to existing buildings.At this time,the active earth pressure on the foundation pit supporting structure of the proposed building may be the common active earth pressure of the trapezoid limited soil.In addition,during the construction of the project,temporary retaining walls are often built to enclose the engineering spoils.Most of these spoils are triangular finite backfills.At this time,they are facing the problem of calculating the active earth pressure under the action of triangular backfills.The calculation of active earth pressure in both cases can be classified as the problem of active earth pressure calculation in limited soils,and the classic theory of active earth pressure calculation is not applicable.Therefore,it is necessary to perfect the theory of active earth pressure calculation for these two types of finite soils.Aiming at the problem of active earth pressure and static calculation of typical trapezoidal finite soil,on the basis of previous studies,the external friction angle,adhesion,overload,tensile depth of filling and tensile cracks,and existing buildings and slipping soils are comprehensively considered The influence of factors such as the interaction between them deduced the corresponding calculation formula.For the dynamic calculation of the active earth pressure of a typical trapezoidal finite soil,the quasi-static method is used to derive the calculation formula of the finite earth's seismic active earth pressure.At this time,the influence of existing buildings on the slipping soil is not considered.In addition,formula derivation and calculation analysis of active earth pressure under the action of triangle filling are also carried out.The main research results are as follows:(1)Based on the Mohr-Coulomb strength theory,the limit equilibrium method and the limit analysis upper limit method are used to derive the calculation formula of the active earth pressure of the finite soil of the typical trapezoid and the calculation formula of the finite and semi-infinite critical state active earth pressure.A more reasonable judgment method between finite and semi-infinite.Through formula comparison,it is found that when the same slip surface is used,the formulas obtained by using the limit equilibrium method and the limit analysi s upper limit method are the same.The critical parameters are compared to the critical aspect ratio,Influence of critical width,active earth pressure and fracture angle of limited soil.(2)The limit equilibrium method is used to derive the calculation formulas for the active earth pressure of finite soil based on the double shear unified strength theory and the three-shear strength criterion,and the calculation formulas for the finite and semi-infinite critical state active earth pressure.Correspondin g influences of critical width-to-height ratio,critical width,active earth pressure and fracture angle of limited soil,and comparative analysis of active earth pressure based on Mohr-Coulomb strength theory,double shear unified strength theory and trip le shear strength criterion Difference.(3)The limit equilibrium method and the limit analysis upper limit method were used to derive the calculation formulas of the seismic active earth pressure and finite and semi-infinite critical state of the typical trapezoidal finite soil body.The influence of critical width,seismic active earth pressure on limited soil and its fracture angle,using orthogonal experiments,the sensitivity of key parameters to seismic active earth pressure on limited soil was obtained.(4)Aiming at the special limited soil body with triangular filling,the limit equilibrium method and limit analysis upper limit method were used to derive the active earth pressure calculation formula,and the influence of key parameters on the active earth pressure and fracture angle was analyzed.