A novel hybrid SPH-DEM approach for simulating rockburst behavior in tunnel excavation

Abstract

A hybrid smoothed particle hydrodynamics-discrete element method (SPH-DEM) is proposed to simulate rockburst behavior during deep tunnel excavation. Within this coupled code, the rock mass continuity stress and elastic deformation are computed by solving partial differential equations (PDEs) via the SPH method. Rock cracking is realized by the transition of SPH particles to DEM particles while considering rock damage. The noncontinuous deformation region is subsequently simulated via a DEM-based method. The contact pairs are established via a link-list algorithm, which enables point-to-point contact to simulate postfracture spalling. Additionally, the dormant particle approach is introduced within the continuous domain represented by SPH to simulate the excavation process, while the confining pressure application method is employed to maintain tunnel boundary stability. The coupling code accuracy and feasibility were demonstrated through three benchmark tests and three typical tunnel case studies. The results indicate that this hybrid method demonstrates clear physical significance, high robustness, and relatively less computational time consumption than standalone DEM code does, making it suitable for addressing practical tunnel-scale issues. In contrast to continuous methods, the proposed approach authentically simulates crack propagation and spalling without necessitating grid reconfiguration. Unlike discontinuous methods, the hybrid method handles the material as a continuous medium before fracturing, allowing for a detailed depiction of the stress and strain before and after failure.