Numerical simulation of polymer grout diffusion in a single fracture

Polyurethane grouting materials, a type of expansible grout, has played a significant role in the rehabilitation of public infrastructures, such as lifting the slab in a road and reinforcing the broken wall rocks in a tunnel. Due to the unique expansion characteristic of polyurethane materials induced by the chemical reaction, its diffusion mechanism in rock fracture is rather complicated. Based on a numerical method presented in a previous paper, the diffusion law of expansible grout in a single fracture is studied considering the time-varying density and viscosity of the grout tested by experiments. The grout diffusion radius, pressure distribution and velocity field are calculated by the numerical model combining the finite volume method (FVM) and volume-of-fluid (VOF) method. Taking the gel time into account, the characteristics of flow field distribution during the grout movement process are investigated on five different cases and the influences of grouting quantity and fracture aperture on grout diffusion behavior are analyzed, which can reveal some diffusion law of expansible grout in a single water-free fracture.