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为全面分析压裂过程煤体的损伤破坏过程,提出水力压裂过程孔壁应变与电阻率同步监测的试验方法,利用自制的水力压裂试验系统,开展原煤水力压裂试验,得到煤体水力压裂过程的孔壁压缩应变–电阻率–水压曲线,分析孔壁应变与电阻率的响应机制。结果表明,煤体水力压裂过程中孔壁应变和电阻率呈现较强的规律性;孔壁应变曲线呈现“V”型,电阻率曲线呈现“■”型,这种变化趋势与水压变化相对应,当水完全占据孔内空间时会导致煤体电阻率达到最小,一旦压裂孔出现破裂,电阻率及孔壁应变会出现突变并逐渐达到最大值;孔壁应变曲线反映出压裂孔承压变形的强度,电阻率曲线则反映出试块内部裂隙的演化特征。煤体孔壁应变–电阻率–水压曲线蕴含了压裂孔承压破裂的丰富信息,为研究钻孔起裂行为提供了一种新方法。
In order to comprehensively analyze the process of damage and destruction of coal in fracturing process, a test method of simultaneous monitoring of wall strain and resistivity in hydraulic fracturing process is proposed. By using the self-made hydraulic fracturing test system, the hydraulic fracturing test of raw coal is carried out, Hole wall compressive strain-resistivity-pressure curve in fracturing process, analyzing the response mechanism of hole wall strain and resistivity. The results show that the strain and resistivity of the wall in the hydraulic fracturing of coal show a strong regularity. The strain curve of the wall shows “V” shape and the resistivity curve shows “” Corresponding to the change of hydraulic pressure, the resistivity of coal will be minimized when the water completely occupies the space in the hole. Once the fracture of the fracturing hole occurs, the resistivity and wall-wall strain will change suddenly and reach the maximum value gradually. The wall-wall strain curve Reflecting the strength of the fractured hole under pressure and deformation, the resistivity curve reflects the evolution of the fracture in the specimen. The strain-resistivity-pressure curve of coal seam wall contains a wealth of information about the fracturing of fractured pores, which provides a new method for studying the fracture initiation behavior.