Investigation Of Earth Pressure And Response Of Foundation Pit Retaining Structure Under Complex Load Conditions

In the process of modernization,as the level of urban construction develops continuously,the density of cities is increasing.Due to the limitations of urban land and other factors,the distance between new underground engineering and existing buildings as well as traffic routes is getting closer,which will lead to a series complex loads,such as earth pressure of confined soil mass and traffic loads.Therefore,how to maintain the stability of foundation pit support structures under these complex loads is an important problem for domestic and foreign scholars.This thesis concerns two major situations(The foundation pit constructed near the main road and the existing building basement).Theoretical calculations,numerical simulations,and field measurements are conducted to analyze the influence of earth pressure of confined soil mass and traffic loads on foundation pit support structures.Research results can provide reference for the design and construction of similar projects.This thesis has carried out the following works(1)A series of numerical simulation are conducted with DEM to study the active failure process of limited cohesionless soil mass behind a rough or smooth supporting structures.The development of the failure surface,the displacement field of the soils and the distribution of active earth pressure are analyzed(2)In order to calculate the active earth pressure problem of limited cohesionless soils based on the discrete element numerical results,an arc path of minor principal stress in sliding wedge behind the retaining wall is assumed,and then calculation formulas of active earth pressure acting on the retaining wall considering soil arching effect are derived using thin-layer element method.An algorithm procedure of the solutions is also presented.(3)Relying on a foundation pit in Hangzhou,vehicle load and vibration acceleration of foundation pit retaining structure as well as dynamic earth pressure after retaining pile under the action of vehicle load are investigated through field measurements.An empirical formula for the calculation of vehicle load at the pit side is proposed.The influence characteristics of vehicle load magnitude and vehicle speed on the vibration performance and dynamic earth pressure are analyzed.(4)A finite element numerical analysis is established to investigate the displacement and internal force of foundation pit support structures under the influence of traffic loads through the d-load program of ABAQUS.Parameter analysis is carried out to analysis the influence of vehicle load magnitude,speed and distance.