Numerical investigation into effects of rheological properties on grout flow in rock fracture using Herschel-Bulkley model

Grouting is an essential technique for reducing the hydraulic conductivity and enhancing the strength of rock mass used in the Dongzhuang hydro-junction project. The rheological properties of grout are not to be disregarded during grouting. In this study, a numerical grouting model is established by combining a modified Herschel-Bulkley (H-B) rheology model with the level set method. The effects of rheological parameters (power-law index n, consistency coefficient k, and yield stress tau 0) on distribution pattern and flow characteristics of the grout are investigated. The H-B model is more effective and precise than the Bingham model for predicting rheological characteristics. Numerical results indicated that distribution pattern and grout volume are primarily determined by n. A low shear rate inhibits the horizontal distribution and reduces the filling capacity of the grout, thus resulting in minimal deposition in the fracture. Grouts with a higher n and k require higher pressure to distribute around the fracture. The reduction in water volume in the fracture is calculated to provide comprehensive understanding into the sealing efficiency of the grout by varying the rheological parameters. This study provides valuable guidance regarding the different rheological parameter of grout in fractures, in addition to a novel concept for the optimal design of grouting distribution.