Rock bolting plays an important role in different geo-engineering applications and its numerical modelling is crucial for the analysis and design of rock structures. Continuum modelling simulation of bolt-reinforced rock masses requires specific techniques to properly model the reinforcement system and its interaction with the rock mass, which often exhibits a nonlinear softening/brittle response. In this context, strain localization might occur, which, in turn, may affect numerical convergence and the quality of results. This paper presents some advanced numerical techniques implemented in PLAXIS to overcome the abovementioned challenges. Firstly, a regularization technique is implemented for an extended version of the Hoek-Brown failure criterion with strain softening. Secondly, the formulation of the structural bolt element interacting with the rock mass is developed. Finally, the robustness and accuracy of these techniques are discussed via a numerical example of a typical underground mining excavation problem.
Rock bolting has been widely used in rock engineering practice. This technology aims at preserving and improving the overall rock mass properties through a load transfer mechanism between the rock and the reinforcement system. Therefore, numerical modelling of bolt-reinforced rock mass is crucial for the analysis and design of rock structures.
The continuum modelling approach, notably the Finite Element (FE) method, has proven to be a powerful tool for large-scale applications as it provides relatively high accuracy with reasonable computational cost, especially compared to discrete element approaches. When dealing with the simulation of bolt-reinforced rock masses, specific techniques are required to properly model the rock mass, the reinforcement system (rock bolts) as well as their interaction. Moreover, rocks often exhibit nonlinear brittle behaviour with softening response which may lead to very restrictive time-step constraints and, more seriously, significant mesh dependency and unreliable numerical results when strain localization occurs (Walton et al. 2014). These aspects may affect numerical convergence and the quality of results, especially in the context of rock-structure interaction. Thus, advanced techniques are needed to enhance computational robustness and reliability.
