ABSTRACT
Cement grouting for fractured rock masses is an important measure for mitigating the adverse impact of groundwater inflow during underground tunnel excavation. In the grouting process, the hardening behaviour of the grout and the hydrogeological environment can influence the grout propagation behaviour. In this study, a numerical model for simulating cement grout propagation in rough rock fractures is established considering grout hardening effects and flowing water. The Herschel-Bulkley rheological model is used to model the non-Newtonian behaviour of cement grout. The phase field method and the complete mass and momentum equations are used to resolve the involved two-phase flow problem. This model is verified against analytical solutions from privious works. We analyse the sensitivity of flowing water pressure and grout hardening rate to grout propagation in rough fractures using this validated numerical model. The results demonstrate that grout propagates non-uniformly from the injection hole to the fracture edge. Grout hardening rate has minimal influence on early-stage propagation but it becomes increasingly significant over time; higher hardening rates result in lower grout filling rates and grout flow rates. The flowing water considerably hinders grout propagation within the rough fracture. Specifically, higher water pressures lead to decreased filling rates but increased flow rates during grouting operations. These findings are potentially useful for improving rock grouting in rock engineering practice under complex flowing water conditions and situations when the cement grout hardening needs to be considered.
