Numerical Simulation Study On Design Of Support Replacement For Architectural Deep Foundation Pit

After the completion of the deep foundation pit excavation and foundation pit into building phase,the original supports need to be gradually dismantled.The deformation caused by support replacement not only relates to the stability and safety of the foundation pit itself,but also has a great impact on the surrounding environment.In this paper,combined with a deep foundation pit project of Nanjing Science and Technology Park,the design of support replacement after excavation is studied.With the continuous development of city construction,technology of support replacement for deep foundation pit is more and more mature.The form of support replacement includes force transmission block,bracket support,inclined bracing and so on.But most of the layouts of the replacement structure are determined by experience.There are few researches on the proportion of support replacement.So based on the previous research work of others,the main works of this paper are shown as follows:1.The energy calculation formula of unit support system is established.The potential energy of the retaining pile,the crown beam and the retaining block generated by the active and passive earth pressure is analyzed.And the impact of the length of support replacement on the lateral deformation of the support structure is obtained by using the principle of the minimum potential energy station value.2.The FEM software PLAXIS 3D is introduced to establish the three-dimensional finite element numerical model of deep foundation pit based on engineering example.The deformation of the envelope,the influence of the surrounding environment and the change of the supporting axial force are analyzed under the completion of deep excavation.And the numerical simulation results are compared with the monitoring data to verify the reliability and rationality of the analysis model and parameter selection.3.Through setting up model,the paper analyzes the lateral deformation of the long and short sides of the deep foundation pit in the phase of support replacement.The result is analyzed and compared with the monitoring data.4.Based on the example of deep foundation pit engineering,this paper studies the influence of the different setting ratio of force transmission blocks at the basement roof on the deformation of the deep foundation pit and the internal force of the structure.