Abstract
The excavation damage of deep tunnels is one of the most important factors contributing to the failure of tunnel structures. In order to investigate the influence of tunnel shapes and fissure geometries, the kernel function in the traditional SPH method has been improved, which can realize the brittle fracture characteristics of particles and can be called the Improved Kernel of Smoothed Particle Hydrodynamics (IKSPH-2D). Meanwhile, the random fissure generation method in IKSPH has been put forward. Different tunnel shapes, fissure geometries, and locations are considered during the simulation of tunnel excavation, and results show that (1) the typical “V”-shaped shear damage zones appear after the tunnel excavation, which is consistent with engineering practice. Meanwhile, tunnel excavation also has an “activating” effect on the preexisting fissures. (2) The stability of circular-shaped tunnel is the best, while horseshoe shaped tunnel is worse, and the “U”-shaped tunnel is the worst. (3) Fissures with small and large dip angles have the greatest influence on the stability of tunnel excavation. With the increase of fissure numbers and lengths, the tunnel tends to be instable. (4) The IKSPH method gets free from traditional grids in FEM, which can dynamically reflect the fracture processes of tunnel excavation. Meanwhile, developing 3D IKSPH parallel program will be the future directions.
Highlights
A large number of large-scale hydropower stations have been developed in western China for its rich hydropower resources
(4) The Improved Kernel of Smoothed Particle Hydrodynamics (IKSPH) method gets free from traditional grids in FEM, which can dynamically reflect the fracture processes of tunnel excavation
These projects are mostly built between high mountains, and the excavations of tunnels will lead to redistributions of stress field, causing the excavation damage zone (EDZ) [1,2,3]
Summary
A large number of large-scale hydropower stations have been developed in western China for its rich hydropower resources These projects are mostly built between high mountains, and the excavations of tunnels will lead to redistributions of stress field, causing the excavation damage zone (EDZ) [1,2,3]. The disadvantages are as follows: (1) quasistatic simulation of the elastoplastic finite element method cannot reflect the dynamic damage processes of surrounding rock during tunnel excavation, which is not consistent with the actual situations. The discrete element method (DEM) gets free from the grids existing in traditional FEM, which can be well applied to the simulations of discontinuous problems [20, 21]. The research results can provide some references for the understanding of tunnel excavation damage laws and some guidance for its support measurements
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