| Granite is widely distributed in various regions of China,especially in the southeast provinces.It is an important medium for the construction of the foundation and the geological environment.Its mechanical properties are greatly influenced by the water,after soaked and saturated,the foundation bearing capacity decreases rapidly due to softening disintegration,with free surface granite residual soil Fang collapse.In recent years Fujian province is implementing the development strategy of the Economic Zone on the west side of the Straits,then economic development and the level of urbanization has improved continuously.However,the economic development is bound to be accompanied by the growing demand for public travel and the urgent need for the transfer of rail transit.As the two leading cities in Fujian’s economic development,Fuzhou’s current public transport has been overwhelmed.In order to ease the growing traffic problems,Fuzhou rail transportation according to the actual situation of the total mileage of about 339 kilometers of the 9 subway lines,a total of 215 subway stations,including 26 transfer station.Xiamen based on the overall urban planning and integrated transport planning and construction of the 6 lines,composed of urban rail transit network,the total length of about 247 kilometers,with 138 stations,including 19 transfer station.The development of rail transportation along with the design and construction of a large number of foundation pit engineering.Therefore,it is important to study the physical and mechanical properties of granite residual soil,and the deformation characteristics of deep foundation pit granite residual soil and its influence on the surrounding environment,which has great guidance for the design and construction of deep foundation pit in Fujian area.In this paper,laboratory soil tests,model test,theoretical analysis and numerical simulation are used to study the characteristics of granite residual soil and the deformation of retaining structure of deep foundation pit under this condition.Its main contents include:1.The mechanical properties of granite residual soil are studied by using the method of three axis compression test and conventional triaxial compression test on the representative soil samples from Xiamen.And the mechanical parameters of granite residual soil are obtained.2.Combined with the practice of deep foundation pit engineering in Xiamen City,the modeling test is used to simulate the excavation of deep foundation pit,and the relationship between force,displacement and deformation of foundation pit is discussed.At the same time,the influence of the space effect and pile group effect is revealed.3.Based on the approximate analytical solution of surface settlement caused by the excavation of the earth proposed by G.H.Lei et al,an analytical elastic solution is derived using the elastic theory to predict the stress and the displacement caused by the construction of rectangular diaphragm wall panel trenches.Secondly,the estimation method of surrounding ground settlement caused by foundation pit excavation is summarized based on the theory of the existing excavation induced ground settlement and verify the feasibility of the method through the example.4.Three dimensional simulation considering the interaction of soil,retaining structure and horizontal support system is established based on the deep foundation pit of Xiamen subway station Interchange Section.The simulation of foundation pit construction process is realized.And the deformation behavior of the retaining structure and the surrounding ground surface caused by deep foundation pit excavation and its spatial effect are systematically analyzed.The research of this paper has some practical value,which can provide reference for the design and construction of the relevant engineering in the future. |
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