Study On The Combination Support Structure Of Soil Nailing Wall And Pile Anchor In Deep Foundation Pit

Foundation pit support engineering plays an important role in the process of urbanization in China.The combination of soil-nailing wall and pile-anchor supporting structure has been widely used in foundation pit engineering,and its applicability has been improved with the development of various technologies.Sanmenxia news building foundation pit engineering,this paper uses FLAC3 D numerical simulation software to establish three different model's ability to control deformation of soil retaining structure analysis,and then analyzing the relation between the soil nailing wall and pile anchor,at the same time,combination of soil nailing wall and pile anchor supporting structure design parameter optimized design,the main work and conclusions are as follows:1.Sanmenxia media building foundation pit engineering,the numerical simulation method(FLAC3D),set up soil nail wall and pile anchor bracing structure of three kinds of calculation model:(1)the conventional design model,namely the upper soil nailing wall design alone,at the bottom of the design of the pile anchor supporting,on the basis of soil gravity stress to convert upper soil load on the top surface;(2)approximate analysis model,that is,the upper soil nail wall design alone,in the design of the lower pile anchor,the upper soil nail wall as a self-stable artificial slope to consider;(3)the overall structure model,that is,the upper soil nail wall and the lower pile anchor as a collaborative work of the overall structure to consider.The deformation regularity and internal force distribution of soil and supporting structure during foundation pit excavation were studied by using these three methods.According to the calculation results of the three models,it is concluded that the overall structure model has the best effect on soil deformation control,which indicates that the soil nailing wall can not only improve the stability of the upper soil,but also improve the overall stability of the foundation pit.2.Combined with the field monitoring data,the displacement law and stress distribution of soil and support structure in the overall structure model are deeply studied,and then the synergism mechanism between soil nail wall and pile anchor is analyzed,so that the overall structure model is most suitable for the actual working state of soil nail wall and pile anchor combined support structure.3.According to the results of numerical simulation calculation,in guarantee under the condition of other parameters constant,altering a gradient respectively according to different design parameters,the combination supporting structure in the different parameters on the soil displacement and internal force of retaining structure,the influence of the change of parameters is analyzed on the sensitivity of influence on the stability of foundation pit.the soil nailed wall height on the effect on the stability of the supporting structure sensitivity is highest.4.According to the results of the sensitivity analysis,some parameters in the overall structure model,such as the height of soil nail wall,the embedded depth of supporting pile,the diameter of supporting pile,the spacing of supporting pile and the prestress of anchor cable,are optimized,and the optimized results are found to be more reasonable than the original plan.