Indirect Boundary Element Analysis Of Ground Vibration Induced By Subway Dynamic Loads

Recently, the subway has becamed an effective method to solve traffic congestion and air pollution in the big city, with its' advantages, such as safety, convenience, fast and saving overground space. But at the same time, the subway induces the vibration of environment along it and affects normal life of people around it. So the study about foundation vibration induced by dynamic train loads has practical significance.Combining with the methods of conjunction, the indirect boundary element method(IBEM) is used to study the vibration of layered foundation induced by dynamic train loads. The model is divided into tunnel in layered half-space and rail pad. And then solve the free field of rail pad during vibration loads acting on the surface of pad. The unit fictitious loads are applied on the boundary of the two regions to simulate the scattering field. Agree with the two regions and solve fictitious loads by boundary conditions to obtain dynamic response of foundation surface.The ground dynamic response induced by subway dynamic loads is studied in the layered elastic and saturied field. On the basis of track irregularity, the subway loads are simulated by exciting force corresponding with the manage standard of irregularity. For layered elastic field, geolofical environmental factors such as tunnel depth, soil thickness, shear wave ratio of bedrock and soil and soil damping ratio are discussed about its' effects on layered elastic foundation. And also the differences between the typical elastic site of Tianjin and its' equivalent site are compared. For layered saturated field, the differences between the saturated field and dry soil field are mainly studied, what's more, some effect factors such as the porosity, viscous coupling coefficient, boundary penetration conditions and soil layers on layered saturated foundation are also studied. And also, take the typical saturated site of Tianjin and its' equivalent site for example. In this paper, some meaningful conclusions are shown which are benefitial to subways' construction and damping isolation, in the future.