Extension of grouting-induced splitting fractures in materials similar to coal rocks containing prefabricated fractures

Abstract

Abstract To reveal the influence of prefabricated fractures (PFs) with different parameters on the extension of grouting-induced splitting fractures, a combination of numerical simulation and physical experiments were used to carry out grouting trials on similar materials to coal rock. The RFPA software was used to simulate the whole process of fracture initiation and expansion of coal rock with PFs during grouting. In the experiment, acoustic emission (AE) technology was used to monitor the extension process of grouting-induced splitting fractures. The results demonstrated that when the PFs do not intersect with the grouting holes, the extension of grouting-induced splitting fractures in rocks containing PFs experienced four stages: splitting and penetrating, slurry filling, fracture splitting and splitting extension. PFs have an orienting effect on the direction of grouting fracture extension and the size of the PFs influenced the extension of the grouting-induced splitting fractures: the larger the size, the easier the surrounding rocks were ruptured, the easier the connection was formed of channels between the grouting-induced splitting fractures and the PFs were formed, and the more complex the secondary splitting pattern in the PFs. This indicated that the angle of PFs played a decisive role in determining the extension direction of grouting-induced splitting fractures. The extension of grouting-induced splitting fractures during grouting of rock mass with different parameters is revealed by numerical simulation and experimental results.