Study On Deformation Control Of Deep Foundation Pit Of Subway In Granite Residual Soil

Granite residual soil is a kind of special soil,have its special engineering properties,distribution in southeast coastal areas in China is very broad.The problems such as the deformation of the foundation pit,the surge and other engineering problems often occur due to the characteristics of granite residual water softening and disintegration in the construction of deep foundation pit of subway station.It is an urgent and important task to study and discuss the engineering characteristics and engineering problems of granite residual soil.In this paper,based on the example of the deep foundation pit of granite residual soil in the coastal area of Fujian,the paper studies the engineering characteristics,deformation and control of granite residual soil.Through theoretical analysis and laboratory test,data analysis and numerical simulation methods to study the granite residual soil engineering properties,the physical and mechanical parameters of foundation pit,deformation and deformation control measures.The main research contents and results are as follows:(1)The paper introduces the cause of formation and division principle of granite residual soil,analyzes the engineering characteristics of granite residual soil heterogeneity,anisotropy,structure,softening,disintegration and so on.(2)The basic physical properties of granite residual soil are determined by means of laboratory tests on granite residual soil in the coastal area of Fujian.Analysis of shear strength characteristics of granite residual soil samples by using three axis instrument.through theoretical analysis and experimental data,the local reference standard and Handbook of engineering geology as well as some scholars research results,the range of the granite residual soil deformation modulus and bearing capacity of foundation are determined.(3)On the basis of summarizing the deformation law of deep foundation pit,the deformation characteristics of deep foundation pit of granite residual soil in Fujian coastal area are discussed.In the area of a granite residual deep foundation pit land iron water and sand gushing accident as an example,combined with the three typical granite residual iron land measured data of deep foundation,analyzes the position of the maximum horizontal deformation of retaining wall,ground settlement,horizontal deformation and ground settlement between the corresponding relationship,and the main reason the accident treatment measures.(4)The finite difference software FLAC 3D is used to calculate the excavation process of the deep foundation pit of a subway line one.The paper studies the horizontal deformation of the retaining structure and the settlement law of the pit and compares it with the actual construction monitoring value.(5)Select the moisture content,the wall depth and steel support stiffness of the three parameters to analyze the factors affecting the deformation of foundation pit of subway station.Explore these factors on the impact of granite residual soil deep foundation pit deformation,and the measures were proposed to control the deformation of foundation pit under different factors.