Construction Monitor And Numerical Simulation Analysis Of Deep Excavation Supported By Pile-anchor System In Hengshui

With the rapid development of China's socialist modernization construction process,the speed of urbanization has brought many problems,one of which is the problem of urban land use.This is forcing people to use underground or high altitude space resources.In recent years,there have been a variety of high-rise buildings and large-scale underground works,and then the complex degree of foundation pit engineering is also more and more high.According to different engineering background,The key to ensure the safety and quality of the project is how to choose the appropriate type of supporting structure and the method of construction monitoring.In many supporting structures,the pile-anchor supporting structure is widely used in the foundation pit engineering with its simple process and safe economy.Although the pile-anchor supporting structure technology is relatively mature,but its theoretical level is still lagging behind the engineering practice,so the research on the stress and deformation of the pile-anchor support system has a strong practical significance.In this paper,a deep foundation pit in Hengshui as the engineering background,and mainly do the following work:(1)Based on the plan of excavation of the foundation pit,some typical data of the excavation process were collected and analyzed;(2)Through the large finite element analysis software Midas/GTS,the foundation pit model was established,and each working condition of the excavation was simulated.The simulation results were analyzed and compared with the monitoring data.(3)Selected five main factors: pile diameter,pile spacing,block solid depth,ground overloading,prestressed anchor,the impact parameter analysis,parameter influence analysis is carried out in order to provide theoretical reference for the design of pile anchor support structure in Hengshui area.Through the research and analysis of the above work,the following results were obtained: The deformation form of supporting pile in pile anchor support system is small and middle displacement between two ends.The settlement of the outside of the vertical foundation pit is shown as “spoon”.The maximum sedimentation value appears in the vicinity of 0.5H.Each layer of anchor bolts for a period of time,all show different degree of prestress loss,along with the loss of the excavation stage after the emergence of the growth of axial force,and ultimately stable in a certain value.The middle of foundation pit support pile lateral displacement of large and bolt axial force larger,instead of foundation pit angle at retaining pile lateral displacement is small and the bolt axial force is small.By comparing the numerical simulation results with the monitoring results,good agreement is obtained,which shows that the numerical simulation method is effective and feasible to study the foundation pit.Pile diameter,pile spacing,block solid depth,the ground overload and prestressed anchor size five factors will have an impact on the deformation of the retaining pile,but the effect is different,need we found five factors each of a most economic security value in the design.