The Deformation Monitoirng Of Retaining Structure And Numerical Simulation About Deep Foundation Pit Of Subway

Based on deep excavation of Wuxi Liangdong road subway station,the Change Regulation of horizontal displacement of diaphragm walls,axial forces of internal bracing system and ground settlement werereseareced by methods of theoretical analysis, field monitoring andnumerical simulation to diaphragm walls with internal bracing system inthis paper. The main research contents is shown as:(1)Based on the environmental conditions around deep excavation,engineering geology and hydrogeololgy conditions and excavation depth，a deformation and internal force monitoring scheme was put forward andmeasuring points had been set up according to the monitoring scheme tofully reflect the deformation of deep excavation.(2)The deformation process of deep excavation in whole processwas monitored in situ.To comparative analysis change rule of lateraldisplacement and ground settlement of diaphragm walls with internalbracing system,a numerical simulation model was established by FLACsoftware.Furthermore, the maximum ground settlements of measured insitu were compared with several calculation methods. The reserachresults show that as the support within the set, the wall horizontaldisplacement and significantly reduce the ground settlement around thefoundation pit.And with an increase in the number of support set inside,the wall horizontal displacement and the ground settlement around thefoundation pit tends to a stable value，the wall near the maximumhorizontal displacement occurs in the pit，and the maximum groundsettlement appeared in about1/2times excavation depth range.(3) Based on the existing theory of inner supporting axial force andthe surface subsidence theory calculation,the calculation results show thatthe large difference between two supporting axial force calculation resultswith the measured results.Therefore, The informatization construction offoundation pit is necessary in order to ensure the safety of the excavationconstruction.(4)The axial force of deep excavation in whole process wasmonitored and the change rules of axial forces were discussed.The monitoring results showed that the axial force and the horizontaldisplacement of first lever brace of long edge were largest on the longfoundation pit edge and the rest of the axial force were not supported.And within the midpoint of the long side supporting axial force weregreater than the rest of the section within the corresponding location ofthe strut axial forces. Within each set in support section, the first line ofsupport is crucial to control the deformation.So，when designing thefoundation pit retaining structure design，on one hand should fully awareof the spatial effect of deformation, on the other hand should pay specialattention to supporting each section of the first line of support strengthand stiffness design, realizing the coordinated unification pit supportingsecurity and the economy.