Stability Analysis Of Deep Foundation Pit Of Metro Station In Hefei Area

With the continuous development of modern cities,a variety of large-scale buildings sprang up like mushrooms,and a large number of high-rise and super-high-rise buildings are increasing.Limited land resources make the contradiction of land shortage increasingly prominent.Urban development is gradually developing underground space.Underground parking lot,underground substation,comprehensive pipeline gallery,subway station and other projects are developing rapidly.A large number of super-deep and super-large foundation pit projects are increasing,which promotes the continuous development of deep foundation pit technology.The excavation of deep foundation pit will inevitably cause the deformation of supporting structure,which will affect the surrounding environment,and is not conducive to the safety of the foundation pit itself and the surrounding personnel.How to control the overall deformation of the foundation pit and reduce the impact on the surrounding environment plays an important role in social economy,which is also a typical technical problem encountered in the process of urban underground space development.Based on the deep foundation pit of Xiuning Road Station of Hefei Metro Station Line 5,this paper establishes a three-dimensional numerical model of the whole foundation pit by using MIDAS/GTS finite element software,and combines with the field deformation monitoring results to analyze the deformation of diaphragm wall and the settlement of surrounding ground during the excavation of foundation pit.The main research contents include the following aspects:(1)Based on the foundation pit project of Xiuning Road Station of Hefei Metro Line5,a three-dimensional numerical model of the foundation pit is established.The settlement of the surrounding buildings,the displacement of the retaining structure in the foundation pit and the uplift of the bottom of the pit are analyzed,and the variation law of the displacement of the retaining structure and the building is obtained.(2)Collect deformation monitoring data of deep foundation pit,analyze lateral displacement of retaining pile,ground settlement around foundation pit and settlement monitoring data of adjacent buildings caused by foundation pit excavation,and reveal the deformation characteristics and rules of foundation pit during excavation.The accuracy of the finite element simulation is verified by comparing the monitoring data with the numerical results.Based on the study of the influence of foundation pitexcavation on the surrounding environment,the deformation control measures to reduce the settlement of buildings are put forward.(3)According to the basic principle of BP neural network,a neural network prediction method for building settlement affected by deep foundation pit excavation is proposed.The monitoring data and prediction results are compared and analyzed to verify the reliability of the prediction model and provide reference for similar foundation pits.