Experimental Study on the Characteristics of High-pressure Foam Fracturing

In view of the shortcomings of the drilling and blasting method and the mechanical method in rock breaking engineering, based on the high viscosity and compressibility of foam, the high-pressure foam fracturing technology is proposed. Firstly, design the high-pressure foam fracturing device, theoretically analyzed the process of high-pressure foam instantaneous release to boreholes, and then built a high-pressure foam fracturing force test device and carried out the experiments of the fracturing force, set up the high-pressure foam fracturing experiment system. Finally, the foam fracturing characteristics with different air volume fractions were investigated, and the mechanism of high-pressure foam fracturing was revealed. The results show that, when the high-pressure foam is released, it can produce a higher fracturing force than the initial foam pressure, but the fracturing force increases and then decreases with the increase of t foam air volume fraction, the high-pressure foam fracturing goes through four stages of crack initiation, crack expansion, crack separation, and end of cracking, the rock breaking weight increases and then decreases with the increase of air volume fraction. When the air volume fraction is 60%, the rock breaking form is blast crater, which is mainly caused by the tensile stress generated by the compressive stress wave reflected on the rock upper surface. When the air volume fraction is 70%-90%, the rock breaking form is stripping large stone, which is mainly caused by the effect of the stress concentration at the bottom of borehole.