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CO2气爆型煤预制楔形裂纹扩展试验研究

Experimental study on wedge-shaped crack propagation in moulded coal with pre-existing cracks induced by CO2 gas fracturing

  • 摘要: CO2爆破在实际应用中存在炮孔起裂能量耗散大、起裂方向难以控制等问题,而诱导裂纹技术能有效解决上述难题。基于自主搭建的CO2气爆试验平台,开展动静载组合条件下含预制楔形裂纹的型煤CO2气爆试验,系统研究不同动静载组合对型煤裂纹形态、张开位移及位移场演化规律的影响。试验结果表明,动静载压力的增大与试样表面裂纹扩展长度、扩展量呈正相关关系,当气爆压力从1.2 MPa增至2.4 MPa时,爆生拉伸裂纹的张开位移由1.084 mm增至4.130 mm;预制裂纹对爆生裂纹的扩展方向具有明显的导向作用。

     

    Abstract: CO2 blasting faces challenges in practical applications, including significant energy dissipation during borehole initiation and difficulty in controlling the initiation direction. Crack-inducing technology can effectively address these issues. Accordingly, based on a self-developed CO2 gas fracturing experimental platform, tests were conducted on moulded coal with prefabricated wedge-shaped cracks under combined dynamic and static loading conditions to systematically investigate the effects of various dynamic-static load combinations on crack morphology, crack opening displacement, and displacement field evolution. The experimental results indicate that increases in dynamic and static loading pressures are positively correlated with the propagation length and extent of surface cracks on the specimen. When the gas fracturing pressure increases from 1.2 MPa to 2.4 MPa, the opening displacement of the tensile crack induced by the explosion increases from 1.084 mm to 4.130 mm. Furthermore, the prefabricated crack exhibits a significant guiding effect on the propagation direction of the explosion-induced crack.

     

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