Experiment Research of Gas Pressure Impact on Surrounding Stress and Deformation of Soft Coal Borehole

In order to study the effect of different gas pressure on stress and deformation of soft coal around borehole, through the experimental steps such as the acquisition of coal samples, coal forming, setting piezoelectric film, drilling implementation and prying, we analyze stress change around the borehole and internal damage and deformation law of borehole under the condition of different gas pressure, it is concluded that stress concentration gradually migrates to the periphery around the borehole, and pressure relief zone expands gradually with the increase of inflation pressure. When it is not filled with gas, the pressure relief zone is about 22 mm around the experiment borehole; under the action of 0.9 MPa gas pressure, the pressure relief range increases to about 60 mm; the deformation destruction of the borehole gradually intensified with the increase of inflation pressure.