Mechanism of stemming slurry materials for pulsating grouting in soft strata

The pulsating grouting with slurry materials is an effective method for anti-seepage and reinforcement in soft strata, but the mechanism of stemming slurry materials is not clear. Based on the engineering fracture mechanics and Bingham fluid concentric annular narrow gap flow model, the mechanism of stemming slurry materials is analyzed qualitatively, and based on the conservation of energy, the governing equation for the stemming slurry materials is deduced. The relationship among the limit loading pressure of slurry materials in pulsating grouting, the rheological properties of grouting slurry, the performance of sealing slurry and the pulsating frequency is analyzed. The limit loading pressure of the slurry materials increases with the increase of plastic viscosity of slurry, yield stress plastic strength of sealing slurry and interval time of pulse, and decreases with the increase of duration time of pulse. The effect increases with the increase of the height of hole sealing. The mechanism of stemming slurry materials is verified by the self-made indoor experimental device. For the anti-seepage project in the slope of the diversion canal in Hebi of Henan, which is in the Middle Route Project of South-to-North Water Diversion, in view of the soft geological conditions, the stemming slurry technology of slurry materials is applied to the slope project by means of segmented pulsating grouting from bottom to top. The pumping tests after grouting indicate that the permeability reaches 10^-5~10^-6 cm/s, and the amount of work of 20% is saved compared to that of the traditional grouting technology.