3D numerical simulations of tunneling induced soil deformations

Abstract

The accurate prediction of the maximum surface subsidence caused by shallow tunneling in soil environments is a valuable criterion for safe design and operation, especially in urban areas. To investigate the surface subsidence due to tunneling, the simultaneous impact of depth and diameter of the tunnel in both saturated and dry conditions have been investigated using a FLAC3D Finite Difference Method. Six models having different diameters (7 m, 8 m, and 9 m), depths (12 m, 16 m, and 20 m), and face pressures (0.34 MPa, 0.36 MPa, and 0.38 MPa) were developed. A step-by-step excavation process of the tunnel advance was considered in the modeling to account for deformations ahead of the face and the shield's effect. Results showed that depth and diameter induce a significant effect on the ground surface displacement values and crown displacement values. As face pressure increases, the effect of tunnel depth and diameter on surface and crown displacements decreases, and the effect of saturation did not change.