Efficient underground mine support as a factor in reducing consequences of rock bursts

The paper presents a finite element study aimed at a comparative assessment of support systems for underground excavations in burst-prone and highly stressed rock masses. The problem is relevant because failure of an underground opening under dynamic ground pressure is controlled not only by the strength of individual support elements, but also by the performance of the entire rock mass-support-surface retention system. The purpose of the study is to compare five support designs within a unified numerical framework under identical initial conditions. A three-dimensional finite element model of an arched excavation was used. The rock mass was described using an elastoplastic Mohr-Coulomb model, and three calculation scenarios were considered, i.e. the base high-stress state, a weakened near-contour zone, and an equivalent dynamic loading case. The support designs were compared by the roof and wall displacements, plastic zone size, stresses in the support elements, contact degradation length, and an integral efficiency index. The results show that the combined system consisting of energyabsorbing bolts and fibre-reinforced shotcrete provides the greatest reduction in displacements and damage of the surrounding rock mass. The base support system without special energy-absorbing elements is the most sensitive to weakening of the border zone and impulse loading. The proposed approach can be used for preliminary selection of support in burst-prone excavations and for execution of detailed design calculations. The novelty of the study lies in comparing five support systems using a unified set of quantitative criteria within one numerical model.