Abstract: The coal wall grouting reinforcement technique is an effective measure to prevent and control rib spalling, and its key procedure is the selection of grouting quantity. To overcome the difficulty in choosing the reasonable grouting quantity, an experimental scheme“The fragmentized and broken coal molded again with mixed slurry”has been designed. The uniaxial compressive and the wedge shear test of coal sample with different proportion of grout has been performed by using the rock mechanics testing machine. The study has shown that: the coal shows much less brittle failure because the grout in it can continue the deformation of the coal sample; the uniaxial compressive strength and residual strength of the coal sample can reach the maximum amount with an appropriate proportion of grout; the shear strength of coal sample is increased because of the grout in it, which is shown as the phenomena that the cohesion of coal sample is increased ,while the influence of friction is little. It has been concluded that the research result can provide the theoretical foundation for the selection of grouting quantity.

Key words: proportion of grout, coal sample, uniaxial compressive test, wedge shear test, coal wall reinforcement