Analysis Of Influencing Factors On Side Shift Of Enclosure Wall Of The Foundation Pit Excavation In Jinxiu DaDao Station Of Hefei Subway

With China's complete construction of a moderately prosperous society and a socialist modernization,the process of the great power has been deepening in all aspects.Moreover,the process of urbanization in all parts of China is gradually accelerating.The development of urbanization has been vigorously promoted all over the country,and the construction of high-rise and super-tall buildings has been continuously built in various places,which has made the underground part more and more concerned.In all kinds of buildings,especially the underground part occupied by super-tall buildings is particularly large,resulting in most of the foundation pit engineering is deep foundation pit engineering.In addition,due to the complex surrounding environment of the foundation pit,the wall deformation and surface subsidence of the wall during excavation are too large,which can cause a great threat to the security of surrounding buildings,municipal roads and underground pipelines.Therefore,the deformation and surface subsidence of the surrounding wall should be strictly controlled during excavation.This thesis studies the excavation of foundation pit of Jin Xiu Da Dao Station.Based on the On-site monitoring data analyzed and the MIDAS/GTS finite element software used for numerical simulation,the factors that influence surrounding wall deformation during excavation of the foundation pit are analyzed.In this thesis,the influence of the thickness of the wall,the rigidity of steel support and the amount of support on the lateral displacement of the wall are studied.And some conclusions are drawn,which can provide some reference for similar projects in the future.The main conclusions of this thesis are as follows:(1)The horizontal displacement of the surrounding wall is compared under the measured and simulated conditions.In general,we can reflect the horizontal displacement of the surrounding wall in the excavation process of deep foundation pit by numerical simulation results.(2)The enclosure wall thickness has the greatest influence on the horizontal displacement of the wall.It can be seen from that comparative analysis of horizontal displacement curve of the wall horizontal displacement corresponding to different wall thickness.With the increase of the thickness of the wall,the maximum horizontal displacement of the surrounding wall is decreasing,but the amplitude is different.When the thickness of the wall is very small,the maximum horizontal displacement of the wall isvery large.Then,with the increase of thickness,it decreases gradually.When the final thickness increases to a certain value,the maximum horizontal displacement of the surrounding wall will no longer change,that is,it will eventually stabilize at a certain value.Therefore,in the deep foundation pit engineering,it is necessary to select the appropriate thickness of the wall,which can effectively suppress the maximum horizontal displacement of the enclosure wall,and also effectively control the construction cost.(3)The stiffness of steel support has a great effect on the horizontal displacement of the wall.It can be seen from the comparison of the horizontal displacement curve of the surrounding wall with different stiffness of steel support.With the increase of the rigidity of steel support,the maximum horizontal displacement of the surrounding wall is decreasing continuously,but the amplitude is different.When the rigidity of the steel support is small,that is,the difference between the inner and outer diameter of the steel support is small,with the increase of stiffness,the maximum horizontal displacement of the surrounding wall decreases greatly.After that,with the increase of the rigidity,it decreases gradually.When the final stiffness increases to a certain value,the maximum horizontal displacement of the surrounding wall will no longer change,that is,it will eventually stabilize at a certain value.In deep foundation pit engineering,select the appropriate steel support stiffness,not only can the maximum horizontal displacement value of the enclosure wall has certain inhibition,but also the engineering cost can reduce.(4)The concrete support at-0.5m has a certain effect on the horizontal displacement of the surrounding wall.It can be seen from the comparison analysis of the horizontal displacement curve of the surrounding wall with the concrete support at-0.5m.Concrete support at-0.5m can reduce the horizontal displacement of the enclosure wall,but the decrease is not very large.Therefore,in the deep foundation pit engineering,the appropriate support number can be selected to reduce the maximum horizontal displacement value of the surrounding wall to a certain extent,so as to ensure the safety of the project.