Study On Pile Foundation Supporting Scheme Of A Subway Station Deep Excavation

With the increase of urban traffic pressure,more and more cities have opened the subway,and the subway station is often deep,so the safety and stability of the foundation pit support is particularly important.Foundation pit engineering is a high theoretical and practical discipline,which relates to the field is quite extensive,in recent years,although more and more people in our country began to join in the foundation pit areas,because our country started relatively late in this field,there are still some problems in the foundation pit structure selection.In the design and construction still exist some unreasonable situation.Taking a subway station in Zhengzhou as the basis,through the analysis of the hydrogeological conditions of the site of the station,combined with the advantages and disadvantages of different enclosure structure and conditions of use,we finally choose the row piles and steel support of the supporting method,we find the solutions of different construction the problem obased on the key technology of the construction process.we do the structure section calculation of the foundation pit using Lizheng software,and calculate the overall stability of foundation pit,anti uplift,anti overturning checking,and then through the hand of purlin,crown and retaining wall and column design in the supporting structure,and the steel support for checking,the main station of resistance floating checking,so as to ensure the rationality of supporting scheme,through research found that the row pile with support for the site of the foundation pit engineering.The main conclusions are as follows:(1)excavation and retaining structure will occur when the horizontal displacement of foundation pit excavation to the bottom of the pit,the maximum displacement often occurs at the bottom on at a certain distance from the top of the pile,about 2/5 pile length.(2)steel brace stiffness of pile deformation,the length of the support stiffness with steel bracing,steel support length is short,the supporting stiffness,pile structure deformation will be relatively small,so in the excavation,we should try to choose short steel support.(3)The supporting structure of the embedded depth have a certain influence on foundation pit supporting effect and weaking the settlement of the soil,but when the embedded depth reaches the design value,increasing embedded depth to reduce the structure of soil by force and surrounding settlement had no significant effect,and it will increase the difficulty of construction,increase the construction cost.