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Take the deep hard top plate as research object, methods include geological survey, laboratory experiments, RFPA calculations, acoustic emission（ＡＥ）, micro-seismic real-time dynamic monitoring were applied to study the evolution of the crack expansion under the double-hole expansion-induced fracture hard rock body. Studies show that, the optimum water-cement ratio is 1∶3, when expansive force is far greater than the tensile strength of rocks. Secondly, under double-hole expansion, the rock fractured along the horizontal position of the double-hole line, and the micro-seismic events were mostly concentrated in the center of the rock body. The energy level was the highest at the 9th hour of fracture. Thirdly, when the expansion pressure reaches 7.8 MPa, the rock begins to fracture, and the stress-free zone near the borehole expands and draws close to the center, forming a cavity with the crack penetration. With the gap penetration, the acoustic emission signal forms a superposition inside the borehole, presenting a bar structure of “small at both ends and large in the middle” with a dense emission signal in the direction of crack propagation on the outside of the borehole.