Experimental Study on the Law of Sandstone Fracture and Strength Damage Under Disturbance of Excavation Stress

Abstract

Numerical simulation and laboratory experiments were combined to study the fine sandstone in the return airway of Ximing Mine. The stress loading and unloading path of the surrounding rock during the excavation process in the roadway was restored by using FLAC3D refined simulation. On the basis of this, the acoustic emission detector was used to obtain two acoustic emission signal distribution characteristics of the breakage process of sandstone specimens under uniaxial compression with and without mining-induced stress disturbance, and reveal the reduction effect of mining-induced stress disturbances on rock strength and their influence law on development process of specimen fractures. The results show that mining-induced stress disturbance has a significant reduction effect on the maximum strength of rock, of which the strength reduction is about 11.43%. Moreover, mining-induced stress disturbance changes the development and expansion direction of the main fractures of the specimen. In the uniaxial loading path experiment, the fractures of the specimens without the influence of mining-induced stress disturbance develop bottom up and finally into a cut-through fracture zone. As for the specimens influenced by mining-induced stress disturbance, even their fractures develop from the bottom, the main fractures initially from the upper part of the rocks develop downwards until a completely physical cut-through fracture zone is formed in the specimen. The study is of great significance in discovering the law of both the surrounding rock breakage at the earlier stage and its subseguent deformation and failure under the influence of the mining-induced stress disturbance and in exploring and determining the reasonable support scheme for surrounding rocks.

Keywords

• mining-induced stress
• loading and unloading path
• fracture evolution
• strength damage
• acoustic emission characteristics