Study of grouting effectiveness based on shear strength evaluation with experimental and numerical approaches

Grouting is an important and convenient technique to improve rock properties. The grouting effectiveness depends on quantities of complex influencing factors. The investigation on the effects is essential for engineering applications. This study focuses on the evaluation of shear strength with experimental and numerical approaches. Firstly, the shear test of rock sample with cement grouting was carried out. Based on the tests, the numerical modelling of grouting was conducted. The effect of normal stress, grouting thickness and strength parameters of grout on the shear strength was studied, respectively. Then, the critical condition of effective grouting was proposed. Lastly, the mechanism in the influencing factors was discussed. Results show that the strength of grouted rock could be improved by increasing the normal stress and the grout parameters and decreasing the grouting thickness. The critical condition of effective grouting involves the grouting thickness and the strength parameters of grouting material. When the condition of effective grouting is satisfied, the grouting effect would be remarkable with additional supports, such as bolts. According to the opening of the dominant structural plane, the grouting parameters should be reasonably designed to meet the critical condition. The results could provide experimental and theoretical methodologies for the grouting design.