Pit Angle Of Special Foundation Pit Pile-anchor Support System Effect Impact Analysis And Optimization Research

Deep foundation pit is a complex three-dimensional space structure,and the deformation of its supporting structure and the surface settlement behind the pit always have significant pit Angle effect,that is,the deformation is small near the corner of the foundation pit,but gradually increases with the approach to the middle of the foundation pit.However,the current design of foundation pit supporting structure usually does not consider the influence of pit Angle effect,but considers the foundation pit as a two-dimensional plane strain problem,and adopts the same support design scheme for the pit Angle part and the middle part of the foundation pit,which leads to the conservative support design scheme for the pit Angle part,resulting in unnecessary waste.At present,there are few studies and optimization designs on the pit Angle effect of pile-anchor supporting system.In this paper,the pit Angle effect of pile-anchor supporting structure is studied by field monitoring data and finite element numerical simulation.The main contents are as follows:1、Through the analysis of field monitoring results,comparing each location crown beam foundation pit horizontal displacement and the displacement of retaining piles change law of differences,the analysis results show that along with the excavation and supporting of foundation pit,crown beam horizontal displacement and horizontal displacement in different location of the foundation pit supporting pile has obvious difference,crown beam and the horizontal displacement of supporting pile in hole Angle is smaller than in the middle of horizontal displacement of foundation pit,showing the middle big on both ends of small displacement variation characteristics,but also show that foundation pit by hole Angle effect obviously.2、Through the finite element software MIDAS GTS NX 3d finite element model is established on the foundation pit engineering,comparison and analysis the simulation results and monitoring results,the reasonable feasibility of the model is proved and discussed according to the results of the three-dimensional finite element simulation supporting piles in the horizontal displacement change rule in all stages of the excavation and supporting pile in deep horizontal displacement,pit horizontal displacement of retaining structure is obtained by calculating the Angle effect.3、The principle of foundation pit is deep foundation pit design software structure design and checking calculation of 3-3 profile analysis,following the safety factor of the most unfavorable conditions meet the specification requirements determine the calculation results,the original supporting structure design as well as within the scope of pit corner effect and to optimize the design of the supporting structure in each excavation stage of supporting pile body deformation,surface subsidence,the overall stability and resistance to uplift the calculation results,the results show that the original supporting structure design and optimization of supporting structure design principle is the calculation results can satisfy the requirements of the overall stability of foundation pit.4、Based on the finite element model of the reasonable Angle effect within the scope of the supporting structure of pit,reconstructs the model with different spacing of anchor cable,anchor cable configuration and different supporting pile diameter is studied,analysis the pile anchor supporting structure of foundation pit,Angle of the effect and the hole Angle effect within the scope of the supporting structure design scheme of optimization;This paper mainly studies the influence of three factors on pit Angle effect: increasing the distance between anchor cables from one pile to one anchor for two piles,reducing the row number of anchor cables and reducing the diameter of supporting piles.To comparative analysis of several different influencing factors,it is concluded that within the scope of pit corner effect of the optimal design scheme of retaining structure of foundation pit engineering in the future similar,when considering the hole Angle effect on hole Angle effect within the scope of the anchor spacing,the number of anchor cable line,and guidelines for the design of supporting pile diameter,on the premise of ensure the safety of foundation pit supporting,can effectively reduce the foundation pit supporting project cost,but also for the study of the pile anchor supporting structure of deep foundation pits hole Angle effect to provide the reference.