An Improved Tunnel-Track Model in Saturated Poroelastic Soils to a Moving Point Load

Zunan Fu,Li Shi,Yuanlei Xu,Yanming Yu,Guoshuai Wang,Wenbo Song,Zonghao Yuan,Meng Gao

doi:10.1155/2021/4482364

Abstract

To predict the mechanical response of a circular cavity/tunnel buried in saturated poroelastic soils to a moving point load, a semianalytical model is provided in this work. The soils are governed by Biot’s theory that describes the wave propagations for saturated poroelastic materials. The displacement and stress vectors for the solid skeleton and pore-water fluid are represented by scalar and vectorial potentials. The governing equations for the tunnel and surrounding soils are solved in the frequency domain with the aid of separation of variables and Fourier transformations. To check the feasibility of the present analytical model, the solution is compared with other available results calculated for the ring load case. The good agreement shows the correctness of the present model. Numerical results suggest that the mechanical response from a moving point load in a tunnel for two-phase poroelastic materials is quite different from that in single-phase elastic materials. The critical velocity of the tunnel-soil system is around the shear wave speed of soils while the second one introduced into the track-tunnel-soil system with very high value is around the critical velocity of the track structure itself.

Highlights

The propagations of ground vibration from underground railways into nearby buildings have become an important research topic due to the fact that more and more metro lines run in urban areas and become closer to the nearby buildings
In Lu’s work, a moving ring load is applied at the cavity surface. e model used in the present work can be modified to simulate the model in Lu’s work. e whole ring of the tunnel is divided into 360Δθ. e displacements are calculated using the present model for each θ nΔθ (n 0, 1, 2, . . ., 359). e total displacements for the present work in Figure 2 are given by the linear combination of the displacement for each θ as follows: ur 􏽘 unrΔθ
It should be noted that at the critical velocity of the tunnel-soil system, the rail and slab responses present a trough value. is is because at this load velocity, the tunnel-soil system is in resonance behavior meaning that its stiffness is low and damping is high, leading to a lower track response

Summary

Research Article

An Improved Tunnel-Track Model in Saturated Poroelastic Soils to a Moving Point Load. To predict the mechanical response of a circular cavity/tunnel buried in saturated poroelastic soils to a moving point load, a semianalytical model is provided in this work. E soils are governed by Biot’s theory that describes the wave propagations for saturated poroelastic materials. E governing equations for the tunnel and surrounding soils are solved in the frequency domain with the aid of separation of variables and Fourier transformations. To check the feasibility of the present analytical model, the solution is compared with other available results calculated for the ring load case. Numerical results suggest that the mechanical response from a moving point load in a tunnel for two-phase poroelastic materials is quite different from that in single-phase elastic materials. Numerical results suggest that the mechanical response from a moving point load in a tunnel for two-phase poroelastic materials is quite different from that in single-phase elastic materials. e critical velocity of the tunnel-soil system is around the shear wave speed of soils while the second one introduced into the track-tunnel-soil system with very high value is around the critical velocity of the track structure itself

Introduction

Numerical Analysis Results and Discussion

The load velocity influencing zone

Conclusions