Study On The Stability Of Deep Foundation Pit Excavation Adjacent To Buildings Under Vehicle Loads

With the development of China's economy,the exploitation and utilization of underground space is increased day by day,nowadays,lots of foundation pit projects can be seen in urban construction here and there.However,the construction environment of these excavation projects is usually complicated.There are intensive vehicle loads on the road around the pit,except for a large number of municipal facilities buried underground and a mass of buildings around the pit.To ensure the safety of foundation pit project during constructing,the impact of vehicle loads on the excavation stability of foundation pit cannot be ignored.It is significantly theoretical and practical to study on the force and deformation of deep foundation pit excavation under traffic loads on construction projects.In this paper,a railway station square deep foundation pit is studied as the background project,and by using the numerical simulation method to establish a deep foundation pit excavation model under the vehicle loads nearby buildings.The model parameters are modified by the monitoring data.According to model calculation results and monitoring data,the influence of vehicle loads on foundation pit excavation on the road around the foundation pit,the internal force and deformation of foundation pit excavation,the factors that affect the size of the foundation pit deformation and the measures for controlling the deformation of foundation pit are studied,the conclusions are summarized as follows:1.The vehicle loads on the road near the foundation pit can increase the internal force and deformation of foundation pit supporting structure and affect the stability of foundation pit excavation.In addition,the influence of vehicle loads occurs in a certain range,the closer the foundation pit support structure is to the road around the foundation pit,the more influence produced by the vehicle loads on the road.2.After the finish of foundation pit excavation,the maximum horizontal displacement of retaining pile appears in the middle of pile body,and the distribution on the middle of the pile is larger than the ends of the pile;The surface settlement caused by excavation is approximately parabolic,at the same time,there is a certain range that the influence of foundation pit excavation on the surrounding surface settlement;The closer the buildings from the foundation pit,the larger the settlement of the buildings,besides,the building settlement near the middle of the pit is larger than the both ends of the pit.3.The displacement of the retaining structure can be reduced by increase the embedded depth of the retaining structure,increase the stiffness of the retaining system,and reinforce the foundation pit bottom soil.4.Compared the results of model calculation with the results of field monitoring,it is concluded that during excavation the internal force and displacement are consistent,showing that the establishment and calculation of foundation pit model are reasonable and reliable,which can be used in internal force and deformation prediction of foundation pit excavation.5.The model calculation results can predict the internal force and deformation of the foundation pit excavation more accurately by modifying model parameters through monitoring data.