Research Of Adjacent To Subway Tunnels Deep Foundation Pit Supporting Structure Optimization Design

Since the nineteenth century sixties,Human invented the subway.Development and utilization of underground space is not simply subway,sewer,the ground buildings extend underground,As well as exhibitions,research laboratories,underground parking,military command center and other facilities are also constantly in extending to the underground space,So there are a variety of technical complexity of deep foundation pit.And supporting structure of foundation pit engineering,determine the quality progress and cost of the pit engineering.But sometimes the design of supporting structure for foundation pit is too conservative,Not fully utilize the advantage of the structural form and material properties,there is the need for optimal design.This article is based on Zhengzhou a deep foundation pit,Common soil in Zhengzhou area are silty clay,silt and fine sand.And experts and scholars do less research of comparing results about the construction monitoring data,software design calculation of Li Zheng and the finite element software simulation.This article based on the existing research results about the law deformation of supporting structure for foundation pit during the excavation process.Using Li Zheng 7.0 software to optimize the original design of the project.Analysis before and after optimization the law of horizontal displacement of pile and surface subsidence around foundation pit.And then use the Midas GTS software to simulate and optimize the excavation process of the two designs.And analyze the law of horizontal displacement of piles and surface settlement around the pit before and after optimization.Comparing the results of construction monitoring data,software design calculation of Li Zheng and the finite element software simulation prove that the optimization scheme is correct,To meet the safety and stability of the foundation pit under the premise of cost savings.Specifically the following work:(1)Detailed enumerated at home and abroad common pit structure system,Comparing the advantages and disadvantages of each supporting structure for foundation pit and their applicable conditions.(2)Analyze pile and prestressed anchor support system's law of horizontal displacement of piles and surface settlement around the pit under each condition in the text.Found that the supporting structure's actual amount of deformation far less than the design control value and monitoring alarm value,There is great room for optimization.(3)Using Li Zheng deep foundation pit 7.0 software to optimize the original design's pile diameter and pile spacing both in Dungou and Biaozhun area.Calculation results show that the deformation of supporting structure are within the control value and monitoring alarm value.At the same time,it is calculated that the optimized structure has a lower cost,achieve the safe and cost-saving purposes.(4)Compare the result that original design's horizontal displacement of pile and surface subsidence around foundation pit calculated by Li Zheng software to construction monitoring data and find that the two laws are consistent and the deformation is close to each other,The results show that the Li Zheng software has some reference value.(5)Using Midas GTS finite element software to analyze the excavation process of the original design and optimized design.Obtain the displacement stress results that the pile and soil produced during each step of the excavation process.Comparing the results of construction monitoring data,software design calculation of Li Zheng and the finite element software simulation,Results show that the deformation of supporting structure are within the control value and monitoring alarm value.By using Midas GTS to simulate excavation could further prove the conclusion which Li Zheng software draw is correct.