Experimental investigation on sealing efficiency of chemical grouting in rock fracture with flowing water

This paper presents an experimental investigation of the main factors that influence the sealing efficiency of chemical grouting in a permeated fracture replica. Chemical grouting has been widely used to control groundwater inrush in underground mining. However, the relationship between the sealing efficiency of grouting and its influencing factors is one of the many critical issues that still remain unsolved. The four factors tested in the orthogonal experiment include the fracture aperture width, initial water flow speed, gel time, and grout take. The sealing efficiency is evaluated and graded by the reduction of water drainage through the fracture after grouting. The experimental results of the orthogonal arrays show that two most influencing factors on sealing efficiency are the initial water flow speed and the aperture width, where the former has a higher impact than the latter. In a comparison with the two other factors, it is found that the grout take and gel time have less influence. The patterns of grout propagation are classified into four types: (1) total sealing off; (2) partial sealing off with erosion along boundaries; (3) partial sealing off with internal erosion; and (4) total erosion. The interaction between the injected grout and flowing water slows down the water flow and the grout starts to solidify at a downstream location where the retention time for grout is longer than its gel time.