Application Of HSS Constitutive Model In Analysis Of Foundation Excavation Whose Bottom Is Granite Residual Soil

As a kind of high risk part project,the deep excavation engineering is difficult to be built and has many risk factors.It is one of the hot and difficult problems in the high-rise buildings construction,subway stations construction and other fields nowadays.And the granite residual soil as a special soil has the engineering characteristics such as water softening,disintegration and easy disturbance,which can bring more difficulties to the project compared with conventional soil.Especially for the Guangzhou area,the granite residual soil is widely distributed,and it is often encountered that the granite residual soil is near the bottom of the pit during the excavation of subway station.At present,there are many researches on Deep Foundation Pit Engineering,while there are not many researches on granite residual soil in engineering practice.In the existing study of granite residual soil,it tend to focus on its engineering characteristics or microstructure.So the study on the excavation engineering which the granite residual soil is near the bottom of the pit has a good research value.The subject of this paper came from the practical problems that the author encountered during the internship in Zhenlong North Station,Guangzhou Metro Line 14.The deformation of concrete diaphragm wall in Zhenlong North Station was very large in general in the process of foundation pit excavation,what is more,there had appeared many cases of monitoring data alarm.Another obvious feature was that near the bottom of most construction section was granite residual soil.In addition to the various construction conditions during construction would affect the deformation of the underground continuous wall,for the excavation engineering which the granite residual soil was near the bottom of the pit,The characteristics of granite residual soil's water softening and disintegration when it met water were also the reason of the deformation of underground continuous wall increased further.According to this background,the author had carried on the following research:(1)It introduces the research status of the theory of granite residual soil and foundation pit excavation at home and abroad and summarizes the characteristics and problems of foundation pit excavation.(2)The engineering background of the project is described,which provides the basis for numerical simulation analysis.and then statistics and compiling the alarm condition of monitoring data of underground continuous wall' deformation.(3)It is pointed out the irrationality of the deformation monitoring of underground continuous wall in the monitoring scheme,and then restoring the actual deformation basing on the monitoring results of the top displacement.At last choosing a representative construction section as the object of this paper according to the monitoring data and the collected material.(4)It introduces the Plaxis software and the basic theory of commonly used constitutive model.And based on the analysis of the characteristics and applicability of each constitutive model,the Hardening Soil Small constitutive model is used to analyze the project.(5)According to the experimental relationship or parameter selection method,the numerical simulation is carried out,and the simulation results are compared with the actual deformation monitoring data.Then based on the field monitoring data,the relationship between several key parameters is back analyzed,and finally the parameters selection scheme is obtained.(6)By considering the influence of the external environment and the construction organization on the deformation of the underground continuous wall,the different working conditions of the construction site are analyzed.Whereafter,in view of the disadvantage of granite residual soil softening and disintegration 2m,the paper analyzes the foundation pit retaining structure under different design conditions.(7)According to the results of the numerical simulation,the corresponding conclusions can be obtained,which can provide reference for the design and construction of the foundation pit excavation of granite residual soil in the future,so as to better limit deformation of underground continuous wall...