Abstract: Grouting is an effective method to seal against water inrush in fractured rock. It is important to study the mechanism of fissure grouting to design the grouting and implement the project successfully. In this paper, firstly, the influence of the rheological properties of the slurry, diffusion path and grouting methods on fracture grouting was analyzed deeply. An improved step-wise calculation method was proposed to describe the fissures grouting process under different grouting diffusion conditions. This method can calculate key grouting parameters, such as the slurry front position, injection pressure, slurry viscosity and pressure distribution in the grouted zone, and grouting rate at any time. Secondly, the improved method was utilized to study the constant-parameters such as constant pressure grouting and constant rate grouting during the grouting process. The reliability and applicability of the approach were verified by comparing with previous results in the literature. Finally, the approach was adopted to investigate the dynamic fracture grouting characterized by staged descending rate and staged increasing pressure in practical engineering conditions. The change laws of the key factors, such as the injection pressure, grouting rate and diffusion distance, were analyzed. Therefore, this study revealed the diffusion mechanism of the dynamic fracture grouting to some extent and provided a meaningful guide for grouting design in practice.

Key words: step-wise calculation method, fissure grouting mechanism, constant parametric grout, dynamic parametric grout, grouting design