Numerical Simulation Of Zoning Support In Deep Foundation Pit Basing On Controlling Deformation Of Building

The excavation of the deep soil will change the stress of the surrounding soil,and lead the soil move.The movement of soil may make foundations of the nearby buildings have passive deformation,which affect their normal use and even destroy buildings.Firstly according to the excavation that has three-dimensional size in Shijiazhuang,the structure of piles with multiple anchor cable is designed;finite difference method is used to analyze the interaction between retaining structure of the foundation pit and the surrounding buildings;Finally,On the basis of results of the analysis,zoning support in deep excavation is designed.(1)When there is no building outside of the slope,through the simulation of the deep excavations,the horizontal displacement and settlement of the soil on slope are analyzed.The results show that the deformation of the slope wall is obviously constrained by the other wall,which is 0.22 times the length of the wall or 2.8 times the depth of pit;the three-dimensional effect of the other slope wall is very small,and can be analyzed by the theory of plane strain.(2)When the horizontal shape of building in the middle of the east slope wall is rectangle,and the west side of building is parallel to east side of pit,the ground subsidence of the building foundation and the deformation of slope are decreasing,as the distance the inner edge of building's foundation from the pit wall is gradually increasing.In contrast to no-building case,the building mainly increases the deformation of the middle slope;when the inner corner's angle of the pit in the horizontal direction is 90 degrees,the range is 1.85 times the length of the building in the direction of the wall,or 0.57 times the length of the slope.When the distance the west edge of building from the pit wall is greater than 1.5 times the depth of the pit,there is no need to consider the effect of the building and the excavation of the earth on the deformation of the slope wall.(3)When the building is close to the inner corner that is 90 degree in the horizontal direction,relatively to the no-building case,mainly in the 1.49 times the length of building that is parallel to east slope,or 0.46 times east slope length,displacement of soil increases.In contrast to the case that the building is in the middle position of the slope wall,the increase of displacement is smaller.(4)According to the requirement that surrounding environment have appropriate deformation and slope wall can keep stable and safe,the different retaining and protection structure can be used at different position of pit.When the inner edge of building's foundation from the east side of pit is 0.5 times length of slope,and the building is in the middle of the slope,increasing the stiffness of supporting structure within the scope that is 1.85 times length of building,ensures that the settlement and differential settlement of building foundation is right.It is possible to reduce the stiffness of the slope wall in inner corner.This method reduces the settlement and differential settlement of the underground pipeline.