Study on Mechanical Properties of Fractured Sandy Mudstone Based on Triaxial Compression Experiment

The technological requirements for mining are becoming more and more complex as underground coal mining depth increases. The issue that the concentration of mining stress causes an increase in the degree of rock fracture formation in the stope is one of them, and it has a significant impact on the mine’s production safety and efficiency. Using a pseudo-triaxial compression experimental platform, the effects of confining pressure on the strength, deformation, and fracture propagation route of fractured sandy mudstone were investigated in order to explore the mechanical characteristics of fractured rock mass. The findings demonstrate that the stress and strain curves of split sandy mudstone vary from those of intact specimens in that they are stepped and have several stress decreases. High frequency and low energy levels are released by fractured sandy mudstone, while high frequency and low energy levels are released by unbroken rock. The strength of sandy mudstone is less sensitive to confining pressure when prefabricated fissures are present. Specimens with fractures have a roughly 80% reduction in shear strength while confining pressure remains constant. The fracture propagation route of the intact rock is parallel to the section where the highest shear stress is found, whereas the fracture propagation path of the fractured sandy mudstone progressively expands from the constructed fracture tip to the specimen border. The degree of fracture development in fractured sandy mudstone is greater under the same stress mechanism, and the rock breaks more readily.