• Solid Mechanics •

### A 2.5-D COUPLED FE-BE MODEL FOR THE DYNAMIC INTERACTION BETWEEN TUNNEL AND SATURATED SOIL

He Chao, Zhou Shunhua, Di Honggui, Xiao Junhua

1. Key Laboratory of Road and Traffic Engineering of the Ministry of Education;Tongji University;Shanghai 201804, China
• Received:2016-06-22 Revised:2016-08-17 Online:2017-01-15 Published:2017-03-21

Abstract:

This paper presents a 2.5-D coupled FE-BE model to simulate the three-dimensional dynamic interaction between saturated soils and tunnels with arbitrary sections.The tunnel is modeled using 2.5-D FEM and the ground is modeled using 2.5-D BEM for saturated porous media.The auxiliary problems are introduced to eliminate the Cauchy singularity of the 2.5-D boundary integral equation.The coupled FE-BE equations are obtained using the continuity conditions on the soil-tunnel interface.The presented model is appropriate for tunnels with arbitrary sections and high computational efficiency.The model is verified through the comparison with the existing models.Finally, a case study of dynamic responses of a quasi-rectangular tunnel in saturated soil due to moving loads is presented.The effects of soil permeability on displacements and pore pressure are investigated.The results show that:(1) The pore pressure decreases drastically with the increment of soil permeability, while displacements are not susceptible to soil permeability;(2) the pore pressure and displacements are mainly distributed in the vicinity of 2m around the loading point;(3) In the direction of gravity, the dissipation of the pore pressure beneath the tunnel is faster than that of displacements;the distributions along the depth to tunnel invert of pore pressure and axial displacement are evidently influenced by the soil permeability.

Key words:

saturated soil|special-section tunnel|dynamic response|coupled FE-BE|Fourier transformation

CLC Number: