Experimental and Simulation Studies on the Effect of Rock Bridges on Rock Failure

The randomness and complexity of rock mass fissure development seriously affects the strength and stability of the rock mass. In order to analyse the influence of different numbers of rock bridges on the strength of rock mass, uniaxial compression and numerical simulation tests of fissured sandstone is carried out to study the influence law of different numbers of rock bridges on the mechanical properties and failure characteristics of rock. The results show that the number of rock bridges affects the damage mode of the rock mass, and when the fissure inclination and the inclination of rock bridges is constant, the damage microcrack development status of rocks with different numbers of rock bridges is different; the increase of the number of rock bridges has an optimising effect on the mechanical properties of the rock mass, and the peak stress and elastic modulus increase with the increase of the number of rock bridges. Under uniaxial compression, shear coalescence occurred in the intact rock specimens, while the fracture-containing specimens changed from shear damage to mixed shear-tension damage with the increase of the number of rock bridges. The damage of the rock specimens containing only 0 and 1 rock bridge are mainly caused by the extended shear cracks at the tip of the prefabricated cracks and the penetrating rock bridges; the rock specimens containing 2 rock bridges produced tensile cracks at the same time as shear cracks are formed, and the damage of the specimens is caused by the joint extension of shear and tensile cracks. When the total length of the co-linear cracks is the same, the higher the number of rock bridges, the smaller the stress intensity factor of the rock mass, and the less likely the specimen will be damaged.