An Improved Form of 2D SPH Method for Modeling the Excavation Damage of Tunnels Containing Random Fissures

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.

Numerical Simulation Analysis of Fracture Propagation in Rock Based on Smooth Particle Hydrodynamics

“…These virtual particles and real particles share the same density and pressure if virtual particles with the same magnitude but opposite direction of velocity are arranged, as shown in Figure 2. Due to the dynamic nature of real particles, it is necessary to regenerate the virtual particles based on the current state of the real particles at each computational time step [25][26][27][28][29][30][31]. number of grids.…”

“…The governing equations for the solid mechanics SPH method are based on the conservation equations of continuum mechanics, which include the equations of mass conservation, momentum conservation, and energy conservation [29,30]. The expressions for these equations are as follows:…”

“…Building upon this foundation, Yu proposed an Improved Kernel of Smooth Particle Hydrodynamics (IKSPH) by altering the kernel function. This innovative approach has successfully simulated the process of crack propagation in fractured materials under compressive states, as well as the failure mechanism of slopes featuring jointed fractures [28][29][30][31][32]. Mu proposed an SPH method that considers the coupling of water-kinetic damage.…”