Investigations on Shear Properties of Soft Rock Joints under Grouting

Soft rocks are widely distributed in deep coal mines, and usually very difficult to keep stable. Grouting is widely used to strengthen the surrounding rocks, and to maintain roadway stability with other reinforcement methods. Because shear failure is one of the most common modes for deep surrounding rocks, research on shear behaviors of grouted soft rocks is very important for understanding the reinforcement mechanism. In this work, soft rocks from the Huainan coal mine were employed to achieve cubic specimens by a special method, and their shear properties under grouting were investigated using the direct mechanical tests. The results showed that grouting strongly affected both strength and deformation characteristics, and the shear mode was changed after grouting. In particular, the normal stiffness was obviously increased with grouting, and the residual shear strength was higher than that without grouting. Based on the grouting effects on the shear properties, the mechanism was revealed, and a strength model was proposed, which could be helpful for practical applications of soft rock grouting, such as optimal selection of grouting parameters, grouting scheme design.