Experimental investigation on chemical grouting of inclined fracture to control sand and water flow

This paper presents an experimental investigation of the propagation of chemical grout in an inclined fracture model to control sand and water flow. The experimental grouting setup for an inclined fracture examines the propagation of chemical grout in water and sand flows by considering the different inclination angles of the fracture. The results show that grouting effectively reduces the discharge of the sand and water mixture. Moreover, the total volume of discharged sand and water is reduced when the fracture has a smaller inclination angle. Further analyses show that there is a critical inclination angle that differentiates two types of grout patterns: the “gel deposition grout pattern” and “erosion dispersion grout pattern”. The former is when the inclination angle of the fracture is less than the critical inclination angle, which is 12.4° in this study, and the water and sand flow can be stopped with grouting. The latter is when the inclination angle is greater than the critical inclination angle, so that grouting will not be able to stop the water and sand flow. The mechanisms of the sealing of inclined fractures are discussed from the perspective of a two-phase flow. It is found that the key to sealing fractures is the formation of a stable sand layer. The grout viscosity and the tendency of the grout to gel not only can reduce the speed of the water flow, but also increase the stability of the deposition of the sand particles, which explains for their improved settlement and the subsequent formation of a porous layer. Finally, the grouting becomes permeation grouting after the formation of the porous layer.