Test and application of self-stress slurry reinforcement for fractured rock masses with different strength

Based on the self-stress slurry reinforcement method for fractured rock mass proposed by the authors, considering the influence of rock strength on the coupling effect of self-stress slurry and rock mass, the paper selected underground sandstone, carbonaceous mudstone, sandy mudstone, and coal as the research objects. Then, the comparative tests of reinforcing fractured rock mass with different strength by ordinary slurry and self-stress slurry were carried out to further analyze the influence of rock strength on grouting reinforcement effect. The composite reinforcement effect of restrained self-stress slurry on the rock mass fracture interface was investigated from multiple angles to reveal the reinforcement mechanism of slurry self-stress. Through several engineering cases of different rock strength, the macroscopic reinforcement effect of the self-stress slurry system on the engineering surrounding rock with different rock strength was analyzed. The results showed that the reinforcement effect of self-stress slurry on the fractured rock masses with different strength, such as soft and hard rock, was greater than that of ordinary slurry. As the strength of the rock mass became weaker, the repair degree of slurry to the fractured rock mass was gradually reduced, and the grouting reinforced rock mass specimens gradually transited from shear failure along the diagonal direction to splitting collapse failure. The self-stress of the slurry improved the restrained state of the slurry-rock interface, and then increased the shear strength of the interface by increasing the friction force. The contact connection effect of the two mediums of slurry and rock had been improved. The cementation density of self-stress slurry-rock interface was significantly higher than that of ordinary slurry-rock interface. The crystal particle distribution, compactness and mechanical properties of self-stress slurry stone were obviously better than those of ordinary slurry. The ultra-fine siliceous self-stress slurry system had achieved good results in the reinforcement of broken soft rock roadways, relatively hard rock roadways, and soft coal wall.