Experimental investigation of strength repairing effects of chemical grouting on fractured porous sandstone under different temperature conditions

Investigation of the seepage characteristics and the corresponding repairing effects of slurry on fractured rock mass is of great significance to grouting theory and operation parameters designing. Several chemical grouting tests under different temperatures and grouted pressures were conducted and the seepage processes were monitored by the LF-NMR (low field nuclear magnetic resonance) technique. The influence of temperature on the flow properties, grouted volume and permeability of slurry were comprehensively studied through the analysis of the NMR T2 response. The effects of temperature on the mechanical performance of grouted specimens after curing were investigated through the directly shear tests. The results indicated that the temperature has an obvious impact on the seepage characteristics, the higher the temperature, the lower the permeability. The mechanical performance of grouted specimen is closely dependent on the grouting temperature, the inter friction angle φ and the cohesion c exponentially decrease as the temperature increases. A temperature dependent shear strength mechanical model of slurry bonding layer was proposed and verified. The findings of this study are useful for the parameters designing of grouting operation in deep-buried tunnels.