Study On Foundation Pit Engineering Technology Of The Yangtze River Floodplain In Hexi Area Of Nanjing

In recent years,with the rapid development of Nanjing Hexi area,there are many high-rise buildings,municipal facilities of foundation pit engineering.Foundation pit engineering has regional characteristics,and the supporting scheme of foundation pit is not the same under different geological and hydrological conditions.In this paper,a project in Nanjing is taken as an example to study the foundation pit support in the flood area of Yangtze River in Hexi area.The main research contents are as follows:1.The flood plain of the Yangtze River in Hexi is a dual structure of river alluvium,which has the characteristics of new sedimentary age,low structural maturity,large thickness change and uneven distribution.The silty clay layer is widely distributed,and its particle size composition is mainly composed of silt and clay,and the clay mineral composition is mainly illite.As a result,the foundation pit in this area is prone to the problems of uneven stress of foundation pit structure,large deformation of foundation pit,diffiy in groundwater and high cost of foundation pit engineering.2.Taking a building in Nanjing as an example,this paper studies the foundation pit engineering in Hexi area of Nanjing.The deformation of foundation pit is controlled by selecting retaining structure,horizontal support scheme,adding soil reinforcement measures,etc.,and the scheme is determined to reduce the impact of adverse geological conditions on foundation pit engineering,while taking into account the economy and construction convenience.According to the characteristics of the project,the demolition plan of the original building and the targeted protection measures of the subway tunnel are proposed.The results of the scheme are calculated and analyzed to verify the feasibility of the scheme.3.Taking the financial building project as an example,the finite element analysis software PLAXIS 2D is used to simulate.This paper studies the influence of different earthwork excavation schemes on the northern subway tunnel and surface deformation in Hexi area.t.