Study On Stability And Optimization Design Of Pile And Anchor Supporting Structure Of Deep Foundation Pit

For deep excavation pile anchor supporting structure parameters change influence on the stability of the problem,relying on the Panjin Jiazhaoye center phase two deep foundation pit supporting engineering,through field monitoring and comprehensive analysis,the method of numerical simulation studies the deformation law of the pile anchor supporting structure,and carry out the different built-in depth,pile diameter,pile spacing,anchor cable angle and length of anchor parameters,such as research on the influence of the supporting structure deformation law.Through the combination of numerical simulation and orthogonal test design,the above parameters are comprehensively evaluated and analyzed to determine the optimal parameter combination of pile-anchor support system.Finally,through the simulation analysis and comparison of the support structure before and after optimization under various working conditions,the rationality and scientificity of the optimization design of the support structure are verified.The main research results of this paper are as follows:(1)It is found from the field monitoring data and numerical simulation results that the horizontal and vertical displacement of the pile top increases with the foundation pit excavation.The maximum deep horizontal displacement of the supporting pile changes from the position of the pile top in the initial working condition to the middle position.The maximum displacement of this project is mainly concentrated at around 8m.After the final excavation,the deep horizontal displacement of the pile body presents as "bow".(2)By analyzing the influence of various parameters of pile-anchor support system on its stability,it can be seen that the pile diameter,anchor cable inclination and anchor cable length have the largest influence on the horizontal displacement of the support pile,followed by the support pile spacing and embedded depth.According to the order of its influence factors,the embedded depth < pile spacing < anchor cable length < anchor cable inclination < pile diameter.(3)In the foundation pit safety and economy under the condition of various factors such as comprehensive consideration,on the basis of orthogonal experiment simulation result and the result of variance analysis,optimized,in this paper,the pile anchor supporting structure of the optimal parameter combination is: the diameter is 800 mm,built-in depth of 5.4m,the pile spacing of 1.7m,anchor cable Angle is 15°,the third row 17 m anchor cable length.The cost of foundation pit after the optimization of supporting structure saved 8.2% of the total cost.(4)Through the analysis of the horizontal displacement of the optimized structure,it canbe seen that the horizontal displacement of the foundation pit after the completion of the final working condition reduces by 1.37 mm,accounting for about 10.8% of the total displacement.Therefore,the optimized structure has an excellent effect on the horizontal deformation limitation of the foundation pit.The paper has 36 figures,16 tables and 56 references.