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二氧化碳相变爆破致裂机理与应用研究进展

Mechanism and application of carbon dioxide phase change blasting fracturing

  • 摘要: 煤岩体结构改造是解决煤矿许多技术难题的共性核心科学问题,二氧化碳相变爆破因其安全可控、能量易调节等优点成为煤岩体致裂的有效手段之一。为确定二氧化碳相变爆破致裂机理,扩展相变爆破致裂工程应用,分析了二氧化碳相变爆破原理和致裂器材与装备,统计比较不同方式相变爆破能量计算方式,相较于传统炸药爆破,相变爆破属于一种低能量致裂方式;通过分析二氧化碳相变射流传播特征,探究相变爆破中等应力起裂和高压气体协同作用方式,煤岩体在中等冲击作用下,受到拉应力破坏产生径向初始断裂,并在冲击波和卸载波综合作用下形成多重起裂特征,高压气体在多重裂隙中进一步扩展,驱动裂隙向外扩展,明确了相变爆破应力气体协同致裂过程;进一步研究了泄能方向、煤岩体性质、爆破参数、初始地应力、钻孔布置参数和钻孔切槽特性等因素对相变爆破致裂效果的影响,泄能方向对煤岩体破坏起到直接作用,引发非对称损伤破坏,煤岩体抗压强度和致裂孔间距是影响致裂效果的关键因素,初始地应力、钻孔布置参数和钻孔切槽特性等影响裂纹发育扩展特征;在相变爆破致裂工程应用方面,揭示了相变爆破多重裂隙渗流特征,确定了高瓦斯煤层致裂增透效果,对比了预裂前后煤体截割特征,验证了预裂提升块煤率可行性,并探究了相变爆破预裂顶板垮落特性。针对相变爆破致裂应从多速率冲击破碎、损伤破坏多尺度分析、致裂过程多物理场耦合及延时相变爆破技术等方向进一步扩展研究,拓宽二氧化碳相变爆破应用场景。

     

    Abstract: The structural transformation of coal and rock mass is a common core scientific problem to solve many technical problems in coal mines. Carbon dioxide phase change blasting has become one of the effective methods for coal and rock mass cracking due to its advantages of safety, controllability, and easy energy regulation. In order to determine the mechanism of carbon dioxide phase change blasting and expand the application of phase change blasting in engineering, the principle of carbon dioxide phase change blasting and the equipment for cracking were analyzed. Statistical comparisons were made between different methods for calculating the energy of phase change blasting. Compared to traditional explosive blasting, phase change blasting belongs to a low energy fracturing method. By analyzing the propagation characteristics of carbon dioxide phase change jet, the synergistic effect of medium stress initiation and high-pressure gas in phase change blasting is determined. Under medium impact, the coal and rock mass are subjected to tensile stress damage, resulting in radial initial fracture. Under the combined action of shock wave and unloading wave, multiple initiation characteristics are formed, and high-pressure gas further expands in multiple fractures, driving them to expand outward, Clarified the synergistic cracking process of phase change blasting stress gas. Further research was conducted on the effects of factors such as energy release direction, coal rock mass properties, blasting parameters, initial geostress, drilling layout parameters, and drilling groove characteristics on the cracking effect of phase change blasting. The energy release direction plays a direct role in the failure of coal rock mass, leading to asymmetric damage and failure. The compressive strength and cracking spacing of coal rock mass are key factors affecting the cracking effect. The initial geostress, drilling layout parameters, and drilling groove characteristics affect the development and propagation characteristics of cracks. In terms of the engineering application of phase change blasting fracturing, the multiple crack seepage characteristics of phase change blasting were revealed, the crack and permeability enhancement effect of high gas coal seams were determined, the coal cutting characteristics before and after presplitting were compared, the feasibility of presplitting to increase lump coal rate was verified, and the collapse characteristics of presplitting roof in phase change blasting were explored. Further expansion should be made towards the direction of multi rate fractturing caused by phase change blasting, multi-scale analysis of damage and failure, coupling of multiple physical fields during the cracking process and carbon dioxide phase delayed change blasting, which will expand the application scenarios of carbon dioxide phase change blasting.

     

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