Experimental study on high pressure nitrogen blasting fracture for coal and rock mass

FIGURE 1: High pressure nitrogen blasting and cracking experimental system of coal and rock mass.FIGURE 2: Molding experimental blocksFIGURE 3: Release tube and its dimensional drawing. (a) Release tube; (b) dimensional drawing of release tube.FIGURE 4: The macroscopic crack morphology on the experimental blocks’ surface under the designed condition of 1L gas volume. (a) P=5MPa; (b) P=7.5MPa; (c) P=10MPa.FIGURE 5: The macroscopic crack morphology on the experimental blocks’ surface under the designed condition of gas pressure of 10 MPa. (a) V=1L; (b) V=2L; (c) V=3L.FIGURE 6: p-t curve of high pressure nitrogen fracturing under different design gas pressure conditions. (a) P=5MPa; (b) P=7.5MPa; (c) P=10MPa.FIGURE 7: p-t curve of high pressure nitrogen fracturing under different design gas volume conditions. (a) V=1L; (b) V=2L; (c) V=3L.