Study on the impact of grouting reinforcement on the mechanical behavior of non-penetrating fracture sandstone

The grouting reinforcement technology is an essential method to enhance the mechanical performance of fractured rock masses and the effectiveness of reinforcement varies with different grouting materials. To further understand the mechanical improvement capabilities of each grout and the reinforcement mechanisms at the grout-rock interface, this study prepared samples with different grouting materials (sulphoaluminate cement (SAC), ultra-fine cement (UFC), and epoxy resin (EPR)) and the uniaxial compression tests were conducted. Based on these tests, the macro and micro mechanical characteristics of different grouting samples were revealed using particle image velocimetry (PIV), acoustic emission (AE), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR). The results indicate that grouting helps improve the mechanical performance and deformation resistance of fractured rock masses. It effectively limited lateral displacement of the samples, reduced stress concentration at fracture tips, enhanced shear effects during sample fracture, and altered the crack propagation process and failure modes. Compared to the fractured samples, the peak strength of SAC, UFC, and EPR samples increased by 17.8 %, 23.4 %, and 28.3 %, and the elastic modulus increased by 14.3 %, 7.9 %, and 24.8 %, respectively. Among these, the EPR samples exhibited a similarity in parameter indicators to intact samples of over 85 %, making EPR the optimal grouting material. The degree of grout-rock fusion is the primary factor influencing grouting reinforcement effectiveness. SAC is covering-type cement, UFC is embedded cement, EPR is a fusion material, and the fusion-type materials are more beneficial for improving the mechanical performance of fractured rocks.