Deformation Calculation Of Frame Prestressed Bolt Support System

With the increasing demand for land,more and more slope engineering accidents happens with an increasing number of slope projects.The deformation and failure of slopes will pose a threat to the use and safety of adjacent roads and buildings,so people pay great attention to the safety of slopes.Deformation and stability have become the criteria for estimating the safety of slopes.Stability has been attached great importance by researchers.In recent years,the research on deformation of slope engineering has gradually become the focus of researchers’ attention.As a support structure widely used in slope engineering,its deformation needs to be studied more.The specific work done in this paper is as follows.(1)Based on Rankine’s and Coulomb’s earth pressure theory,considering the friction force between the back of the wall and the soil and the load on the top of the slope,this paper deduced the earth pressure acting on the supporting structure under the critical state based on the static equilibrium condition.(2)Under the action of anchor’s tension,the supporting structure works in coordination with the soil,so they deform together.Therefore,a calculation model considering the cooperative work of beams,columns in the frame and soil is necessary to be established.By applying Winkler elastic foundation beam model,regarding the beams and columns in the frame as infinite beams and semi-infinite beams,respectively,the deformation formulas of semi-infinite beams at any position under a concentrated force were derived.Regarding the beams and columns as whole,the deformation calculation model of frame beams and columns was established.The forces from the anchor’s tension distributed on beams and columns were calculated according to the coordination conditions,and the deformations of beams and columns under anchor’s tension were calculated.The soil deformation in the anchorage section was deduced by applying the Mindlin solution.The total deformation of the anchor was calculated,so as to obtain the deformation of the frame pre-stressed anchor support system.(3)Taking a practical engineering project as an example,building a model by a software,using strength reduction method for reference,three kinds of elastic modulus modes,which were that the elastic modulus was constant,that the elastic modulus gradually increased with soil depth increasing,and that the variable modulus elastoplastic strength reduction method,were used to simulate the failure process of the slope.The deformation of the surface of the slope supported by frame bolt support structure during the process was obtained.By comparing and analyzing the deformation law of the slope surfaces,it is found that the displacement of the slope is smaller comparing the actual slope engineering when the elastic modulus was constant.In actual slope engineering,the elastic modulus of soil decreases when the slope fails.Therefore,the deformation obtained by the method of variable modulus elastoplastic strength reduction is more realistic.