Supporting Design And Monitoring Reinforcement For A Deep Foundation Pit In Lanzhou

With the development of urban construction,Foundation pit engineering technology is changing into each passing day.In recent ten years,the development of large-scale underground space in major cities i n China has made rapid progress,and a large number of complex foundation pits engineeri ng projects have been developed.The foundation pit engineering has developed to the ultra-deep and wide information and safety monitoring technology.Design theory,construction methods and construction management technology put forward higher requirements.Based on the engineering background,the theory of combined support of soil nailing wall an d pile and anchor is summarized,and then the deep foundation pit project is supported.The simulation results are compared with the actual monitoring data,and the results show that:(1)The excavation process of the deep foundation pit is s imulated by PLAXIS2 D V2016,In the foundation pit support structure,soil nailing wall or row piles prestressed anchor(cable)support structure is widely used,but the combination of the two support is relatively small,through the project The application of the supporting s tructure in the loess area of the northwest is validated.(2)Under the joint support structure of so il nailing wall and pile anchor,the lateral displacement of soil nailing wall is larger due to the passive support form.In the pile-anchor support section,The deformation of large and prestressed bolts(cable)can effectively limit the deformation of the side wall of the foundation pit.At the same time,it is found that the deformation of the pit wall of the soil nailing wall is related to the deformation of the pit wall,This relevance need further study.(3)Using PLAXIS2 D V2016 finite element analysis software to analyze the construction process of the foundation pit in detail,the process of the whole displacement field and the horizontal displacement field during the excav ation of the foundation pit are obtained.At the same time,Pile deformation and force,and finally the results of the analysis and monitor ing results are more consistent.(4)Due to the leakage of pipeline water during the construction process,the original support structure of the foundation pit is invalidated.Through this analysis,the reinforcement scheme is putting forward.Through the monitoring of the post-pit monitoring point,the monitoring value changes meet the design requirements,indicating that the reinforcement program works well.