Deep Foundation Pit Pile Anchor Supporting Structure Numerical Simulation And Optimization Of Pit Angle Effect

Deep foundation pit is a complex three-dimensional space structure,the deformation of its supporting structure and the surface subsidence behind the pit often have significant pit angle effect,that is,the deformation near the corner of the foundation pit is small,and the deformation gradually increases as it approaches the middle of the foundation pit.However,at present,the design of foundation pit supporting structure usually does not consider the influence of pit angle effect.Instead,the foundation pit is regarded as a two-dimensional plane strain problem,and the same supporting design scheme is applied to the foundation pit angle and the middle part of the foundation pit.As a result,the design scheme of foundation pit angle is conservative and unnecessary waste is caused.This paper,taking a deep foundation pit engineering in Handan area as an example,based on field monitoring results and simulation results,the deformation of foundation pit supporting structure and the surface subsidence are analyzed after pit,found deep foundation pit in the corner of the pit construction process has obvious effect,the specific study on the effect of hole angle range,and optimize the influence within the scope of the supporting structure design.Based on the analysis of the field monitoring results,this paper obtained the change law of the horizontal displacement of the crown beam along the long direction of the edge,and the change law of the horizontal displacement of the support pile along the depth direction,and found that the foundation pit has obvious pit Angle effect.Then,ABAQUS finite element software was used to build a numerical model,and the simulation results and monitoring results were compared and analyzed,so as to verify the rationality of the model.According to the simulation results,the variation rules of horizontal displacement of support pile and surface settlement after pit are analyzed,and the influence range of pit angle effect of horizontal displacement of support structure and surface settlement after pit is obtained.Finally,the optimization methods of increasing the transverse spacing of anchor cables and reducing the diameter of supporting piles are selected to optimize the supporting structure within the influence range of pit Angle effect.After optimization by increasing the distance between anchor cables from one pile and one anchor to twopiles and one anchor and reducing the pile diameter to 700 mm,the overall stability of the foundation pit meets the requirements.The main influence range of pit angle effect is reduced by 7.0m and 3.0m respectively,and the optimization effect is significant.The optimization results of the two optimization schemes are compared and analyzed,and the optimal optimization scheme is to increase the distance between anchor cables from one pile and one anchor to two piles and one anchor.It not only effectively reduces the cost of foundation pit support project,but also provides a reference for studying the pit angle effect of pile and anchor support structure of deep foundation pit.