Abstract
Moving loads will have a certain impact on the safety of the structures. Since concrete is a viscoelastic material, the elastic concrete model cannot describe its viscoelastic characteristics under moving loads. It is necessary to establish a model that can describe the viscoelastic characteristics of concrete materials. In addition, the layered of the soil is also an important factor affecting the propagation of subway vibration waves. Considering the effects of the properties of the concrete material of the subway tunnel structure and the layered soil foundation as well as the load velocity on the vibration of the ground surface caused by the moving load, the standard linear elastic solid Euler beam model is described for the subway tunnel structure in this paper. The equivalent stiffness of the layered soil-viscoelastic beam coupling system subjected to a moving load is formed by using the transmission and reflection matrix (TRM) method. The numerical solution of ground surface displacement caused by subway tunnel in time-space domain is obtained by IFFT algorithm. The correctness of the algorithm is verified by comparing with the reference results. Numerical results show that, with the increase of the viscous coefficient of the viscoelastic Euler beam, the vibration amplitude of the ground surface will decrease. Up to a certain value of the increasing the viscous coefficient of the Euler beam, it will have little effect on the vibration amplitude of the ground surface. Therefore, the standard solid model of viscoelastic Euler beam can well describe the creep and relaxation of materials. The model of viscoelastic beam is reasonable for the working condition of subway tunnel concrete structure. At high speed of moving load, the maximum value of ground surface displacement spectrum will appear at the smaller frequency domain and the maximum value of displacement spectrum will also increase for the soft layer soil, while it is opposite to that of the stiffer layer soil.
Highlights
Vibration induced by subway traffic is a major concern for civil engineers as it causes annoyance to residents or even damage to adjacent structures
The vertical and horizontal displacements of the observation point with weak interlayer in the layered soil can reach the maximum value in the case of vc 0.5vs, and there is definite fluctuation
In this paper, considering the viscoelasticity of the concrete material of the subway tunnel structure and the layered soil foundation, using the standard linear elastic solid model and the transmission and reflection matrix (TRM) method, the characteristics of the vibration of the ground surface caused by the different load velocity in the layered soil foundation are analyzed
Summary
Vibration induced by subway traffic is a major concern for civil engineers as it causes annoyance to residents or even damage to adjacent structures. Xu et al [20] applied the TRM method to the dynamic response of an infinite Euler beam on a layered saturated half-space soil subjected to a moving load. Li et al [31] analyzed the amplitude-frequency response of the control model for forced vibration of the nonlinear viscoelastic Timoshenko beam in the steady state, and the numerical simulation was used to investigate the influence of the damping of viscoelastic materials and external effects on the stable state of the structure. The layered soil-viscoelastic Euler beam model subjected to a moving load is used to analyse the surface vibration characteristics caused by subway tunnels in the layered soil. E elastic modulus, viscoelastic damping coefficient of the viscoelastic Euler beam, and the influence of layered soil on the vibration of the soil surface are calculated and analyzed by means of the calculation model in this paper.
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