Study On The Calculation And Analysis Of Deformation In Deep Foundation Pit With Pile Anchor Supporting Structure

In deep foundation pit engineering,the pile anchor supporting structure system has become a widely used support form,because of its advantages in deformation control,convenient for earth excavation and good economic benefits.At the same time,cause of the complexity of its own,the engineering practice is often ahead of theory research.Foundation pit engineering is becoming more and more complex,and the surrounding environment puts forward to more strictly limited measurements to the deformation of foundation pit,thus the study on the deformation law of foundation pit,the influence factors and the corresponding calculation theory become very important.Due to the adoption of the classical earth pressure theory in the calculation of earth pressure acting on retaining structure in the current design of general supporting structure,which is not tally with the actual situation,and the actual earth pressure in engineering is the result of earth interaction with supporting structure.At the same time,the foundation pit engineering has a strong regional characteristic,the deformation form and laws of foundation pit under different status of soil is also in a big difference.Therefore,this paper mainly attempt to study on the above problems by means of theoretical analysis combining numerical simulation method,the main research content are as follows:(1)Based on the nonlinear interaction elastic method,the limit earth pressure theory which considering the deformation was lead in,and a new deflection differential equation of the supporting pile was gotten,after the introduction of constraint conditions,a program was written by MATLAB software to calculate the horizontal displacement of the pile body,thus get the curve of the horizontal displacement on pile.The analysis results show that in the method considering the limit state the earth pressure for the horizontal displacement of the pile anchor structure,the relationship between earth pressure and displacement of pile body can be considered well.By using this method,the man made error due to inexperience can be avoided when determining the level reaction coefficient of foundation soil compares with the existing method of elastic subgrade reaction method.(2)By using the method of numerical simulation,the factors for soil settlement of the ground surface and deep soil was studied in the pit with pile anchor supporting structure,thus get the sensitive degree of sedimentation value for each parameter.It was found that the change of soil parameter influence much obviously on the subsidence of foundation pit.The change of pile stiffness barely influences on the settlement of foundation pit,but the appropriate increase of embedded depth of the solid pile still can reduce the ground subsidence.The appropriate increase of prestress and stiffness of anchor can reduce the settlement in ground surface of foundation pit,but the restriction on settlement of foundation pit is very limited.The overload changes influences obviously on the surface soil subsidence of foundation pit,the limitation of the overload value can effectively reduce the surface subsidence of soil in the excavation of foundation pit.(3)A design method based on the deformation control of deep foundation pit for the pile anchor supporting structure is given combined with an engineering example,and the method is proved to be a practical method through the practical application.