Monitoring And Mechanism Study Of Stressing-deformation Of Pile-anchor Support System For A Foundation Excavation In South Beijing

With the deepening of reform and opening up and the sustained and high-speed development of national economy in China,various engineering construction have developed rapidly.In order to meet the needs of engineering construction,pile-anchor retaining structure has been widely applied in engineering and gradually developed.It has become one of the most commonly used basic supporting forms in deep foundation excavation supporting engineering.At present,the research on pile-anchor retaining structure mainly focuses on stress and deformation calculation theory,construction control technology,application characteristics and application fields.In this paper,I studied deformation and stress loss in foundation pit.The following results has been done by using the concept of dynamic design combined with the actual project involved in design,construction control and monitoring feedback.The following results are obtained(1)The relationship between the stress loss of the pre-stressed anchor cable and the change of the load overload around the foundation excavation is studied and obtained,especially the relationship between the change of the axial force and the size of the load around the foundation excavation and the load form(dynamic load and static load).(2)In pile-anchor retaining structure,the deformation of supporting structure and ground is studied when the lost axial force is used to lock directly,and the contribution of the locked axial force to control the deformation of foundation excavation and ground is analyzed and determined.(3)In the dynamic support of foundation excavation,under the condition of compensatory tension of the axial force of anchor,the deformation of ground is studied and compared,and then the relationship between the displacement of pile body and ground settlement is analyzed and determined.(4)Using the finite element software MIDAS,the difference between the ground settlement value,the maximum stress value of the pile body and the minimum stress value of the pile body under the two states is analyzed,and its influence on the stability of the foundation pit is analyzed and determined.(5)Based on the contradiction between the engineering practice and the requirements of local codes,this paper compares the changes of axial force locking in the new codes for foundation excavation support,analyzes the characteristics of the requirements of the newcodes for this problem,and puts forward some suggestions based on the discussion and analysis results.