The Research On Deep Foundation Pit Cxcavation Optimization And The Lower Subway Tunnel’s Deformation Control

Deep foundation pit engineering is one of hot and difficult problems in rock soilengineering. How to effectively control deformation of foundation pit and make foundationpit engineering safe and economic is the task that people always probe. Deformation forretaining structure of foundation pit is an important factor for effect on the deformation offoundation pit. On the basis of reading lots of relevant researches at home and abroad andsummarizing former research achievement, in view of displacement, deformation behaviorof pit-retaining structure during the processing of deep foundation excavations, analyses ofcalculating method for excavation by steps and practical engineering measurement havebeen finished, on the ground of engineering of support of Nanjing Ning-Wu railway deepfoundation pit. Then, using Midas/GTS finite element program, displacement field, internalforce have been calculated in the progress of excavation of the practical engineering. thedeformation of the support structure and its effect on the foundation pit have beenemphasized in the thesis, from which some significative orderliness have been elicited.In this paper, the main jobs and conclusions include:（1）According to the practice of deep excavation adjacent to the Nanjing Ning-Wuundesirable railway relocation subway tunnel line range of deep foundation engineeringbacked by theoretical analysis and the method of combining on-site monitoring of deepexcavation of the deformation mechanism of the Deep Base Pit were analyzed by analysisof monitoring data, according to the measured data of the enclosure to optimize the designof reinforced concrete piles study, by optimizing the research around re-reinforced piles.（2）the retaining structure in deep foundation pile deformation envelope to complete theexcavation process of Midas/GTS simulated and foundation deformation,the numericsimulation of internal forces, displacement of support pile and steel Analysis supportingforce in construction has been carried out.simulation results are in agreement with theon-site monitoring.Through the establishment of three-dimensional model to analyze thestability of the foundation factor.technical support for data analysis and early-warningsystem in monitoring was provided.（3）According to the practice of deep excavation adjacent to the subway tunnel inNanjing, the software Midas/GTS is employed to establish a numerical model to simulatethe whole dynamic process of the deep excavation.The calculated results show goodagreement with the field measurements.The key factors influencing the operation tunneldeformation during the foundation pit excavation are analyzed through theoretical analysisand numerical simulation calculation.The results show that foundation pit excavationcausing the tunnel displacement.The stress state of the tunnel segment also changes, anddiscusses the control measures.