Abstract: Though fracture grouting technique has been widely used in underground engineering, the theoretical study lags far behind engineering practice. Based on the assumption of power-law fluid and narrow plate model of grouting diffusion, a formula for calculating the maximum diffusion radius of a power-law fluid is deduced. The scope of application and the method to determine parameters are analyzed, and the formula is validated by means of filed grouting tests. The findings are as follows: 1) the maximum diffusion radius of fracture grouting is related to grouting pressure, front surface pressure, crack width, viscocity coefficient, average flow rate of grout and flow behavior index; 2) the maximum diffusion radius increases with grouting pressure difference, and grouting pressure difference reduces with the increase of crack width; 3) according to field test results, the error between theoretical calculation value and actual measured value of the maximum diffusion radius of the power-law fluid is obtained, which proves that the formula is correct and applicable. The results provide theoretical and technical support for similar grouting projects.

Key words: power-law fluid, maximum diffusing radius, fracture grouting mechanism, formula, grouting pressure