Stress And Deformation Analysis Of Retaining Structure In The Soft Soil Foundation Pit In The Whole Construction Process In Foshan Area

Research about stress and deformation of retaining structure in foundation pit placed at soft soil area is a hot topic.In the process of excavation and removal of support,the retaining structure begin to deform variably.In order to strengthen the safety and stability in the process of the removal of support,a soft soil foundation pit in Dongle Road Station of Foshan Metro Line 3 is taken as the object,with the field monitoring data be based on,the finite element analysis model be combined with,the stress and deformation during the removal of support about the retaining structure is analyzed.The transformation of soil and water pressure on diaphragm wall,supporting axial force and internal force of station main structure during foundation pit construction is proposed,and the method to reduce the deformation of retaining structure caused by construction is proposed.Firstly,based on the field monitoring data,the deformation about diaphragm wall in the process of excavation is analyzed,and the conclusion is drawn as that,the maximum lateral displacement of diaphragm wall is proportional to its position and excavation depth.Then the deformation of the wall during the removal of support is investigated,the deformation increment between two adjacent working conditions,the influence of air effect on the deformation increment of diaphragm wall are corrected,so as to reflect the influence of the removal of support on the deformation of the wall intuitively.Further more,the stress state of the support that placed at different position during construction is analyzed,and that can provide the basis for the real stress analysis of the support.The foundation pit construction process of Dongle Road station is simulated through ABAQUS,and simulation data are extracted and compared with the field data to verify the reliability of the numerical simulation.On this basis,the situation that the transformation of water and soil pressure difference on both sides of the wall into internal force of support and station main structure in the process of foundation pit construction is carried out.The conclusions are drawn as follows: At the stage of excavation,the ratio that the internal force of retaining structure that transformed from the difference of the water and soil pressure on both sides increases continuously;at the stage of the removal of support,the ratio that the internal force of station main structure that transformed from the difference of the water and soil pressure on both sides increases continuously.At last,with the finite element foundation pit model be relied on,and by modifying the retaining structure under different parameters,the deformation of the wall after construction,and the conversion rate that between the water and soil pressure difference on both sides of the wall and the internal force of the station main structure are studied.It is concluded that in the design of controlling the deformation of diaphragm wall,the influence of the position of foundation pit support should be given priority,and then the thickness of the top plate,middle plate and bottom plate in the main structure of the station should be considered.