How important is the intermediate principal stress component for underground rock engineering?
摘要
Approaches in rock engineering practice are empirical, analytical, and numerical. All of them overlook the significance of the intermediate principal stress component, which may give inaccurate stability assessment results. A novel three-dimensional elasto-plastic model, an extension of the classical Hoek–Brown model known as the EHB numerical model is implemented in the FLAC3D framework to describe and capture the complex response of rock mass under varying stress states. The simulation results using the EHB model show exemplary a significant reduction in the volume of plastic zones in a mine pillar, a horseshoe shaped drift, and a twin circular tunnel, compared to the classical HB model. When an anisotropic stress state is applied to the horseshoe drift, plastic zones are induced in a horizontal and vertical butterfly-shaped pattern. The extent of the plastic zones using the classical HB model is significantly higher than the extent for the EHB model. The pattern of the plastic zones as well as the influence of the intermediate principal stress component differ under isotropic principal stress conditions. Here, the influence of the intermediate stress component is less significant. The factor of safety calculated by the proposed strength reduction technique improved from 2.3 with the classical HB model to 2.7 with the EHB model, emphasizing the practical impact of the proposed model. This study intends to demonstrate the critical importance of considering the intermediate principal stress component to accurately and realistically assess safety and stability for rock engineering structures.