Research Of Spatial Effect And Stack Effect On Subway Deep Foundation Pit Stability

With the rapid rise of the subway in the city,deep foundation pit engineering will be widely used in the deep foundation pit of the subway station.The current design of deep foundation is designed in accordance with the two-dimensional plane strain with little regards for the presence of spatial effect of excavation.For around foundation stack,the load of the foundation is generally 20kPa based on the experience value,and the effect on the stability of the foundation pit seldom considered stack the following pavement stiffness,stack shape.In this condition,research of the space effect and stack on the effects of deep foundation pit stability,has a certain practical significance and practical value.This paper analyzes and studies the distribution of displacement of the wall,earth pressure after the wall welcome,the wall moments with the result calculated by using MIDAS/GTS simulation software,relied on the Fuzhou subway station of Da Dao station deep foundation as a research object.The main results of this paper are included below:Firstly,according to comparing the measured data to the results of numerical simulation software,then invert reasonable physical parameters of the soil.Know the distribution rule influence of wall displacement of different spatial location,wall face soil lateral earth pressure,the wall bending moment according to the different construction conditions to simulate the excavation and the steps in the method of excavation,and analyze the space effect rule.The results show that spatial effect of the longitudinal and transverse foundation pit is obvious and the whole excavation method and the step excavation of foundation pit spatial effect law is different.Secondly,know the distribution rule influence of the different spatial position wall displacement,wall face soil lateral earth pressure,the wall bending moment and analyze the space effect rule by establishing 3D with simulate different sun angles size,sun angle side.The results show that spatial effect of foundation pit external corner is obvious,and angle size,side length of external corner effect on spatial effect distribution law.Finally,know the distribution rule influence of the wall displacement,wall face soil lateral earth pressure,the wall bending moment by establishing a standard sets up three-dimensional model with simulation of different stack size,the road surface rigidity and stack shape.The results show that the size of the stack,road rigidity and the shapes of stack have an affect on the stability of the foundation pit.