Research On Finite Element Simulation Of Foundation Pit Deformation Under Different Geological Conditions

With the accelerated process of urbanization in China,more and more underground space is exploited.At the same time,the environmental problems caused by excavation are becoming more and more prominent,and the control of deformation of foundation pit is becoming more and more strict.The pile-anchor support system has the advantages of strong deformation control capability,small construction space requirement,stable and safe,and is widely used in deep foundation pit engineering.In addition to pile spacing,pile embedded depth,anchor angle,stress value and other factors in the design of pile and anchor support structure,soil conditions are also important factors affecting the effect of foundation pit support.In order to achieve the unity of economy and safety,it is necessary to comprehensively consider the conditions of foundation pit and analyze the influence of soft soil and hard soil on the deformation of foundation pit.In this paper,the finite element analysis software is used to simulate the two-deep foundation pit under the conditions of hard soil and collapsible soft soil in TongLiao area.The numerical simulation is carried out by using Midas finite element analysis software.The paper analyzes the displacement of soil and pile body in different geological conditions in the process of foundation pit excavation.By comparing the displacement of foundation pit under different working conditions,the following conclusions are obtained:(1)When the excavation depth is small,the excavation process of the deep foundation pit under the condition of collapsible soft soil,because of its anchor cable pulling effect,causes the foundation pit surrounding surface to appear as uplift deformation,the deep horizontal displacement of the retaining structure obviously converges at the location of the anchor.While the deep foundation pit engineering under the condition of round gravel geologic condition is not obvious in the process of anchor cable pulling.(2)The deformation of the deep foundation pit under soft soil or hard soil condition shows the spatial effect,that is,the deformation of the end point of the retaining wall of the deep foundation pit is very different from the deformation of the middle area of the retaining wall.The deformation of the end position is greater than the deformation of the middle position.(3)When the flexural stiffness of support structure is changed,the deformation of the retaining structure and the settlement of the surrounding soil show a certain deformation law,that is,the greater the bending stiffness,the smaller the deformation of foundation pit,and soft soil conditions Under the deformation of the pit than the hard soil conditions is more obvious.