Analysis of mechanical mechanism and damage characteristics of new fracturing device gas producing tool weakening hard roof
DU Jian1，ZUO Jianping1，2，WU Genshui1，ZHAO Shankun3
(1. School of Mechanics and Civil Engineering，China University of Mining and Technology(Beijing)，Beijing 100083，China；
2. State Key Laboratory of Coal Resources and Safe Mining，China University of Mining and Technology(Beijing)，Beijing 100083，China；3. Mine Safety Technology Branch，China Coal Research Institute，Beijing 100013，China)
Abstract：To study the mechanical mechanism and damage characteristics of the new fracturing device gas producing device weakening hard roof，the dynamic model of multistage weakening hard roof with gas producing tool is established，the effective stress and damage degree of the roof during the weakening process are calculated，and the morphological characteristic change and damage characteristic evolution of the roof are obtained. The results show that the high-pressure gas pre-expands the primary cracks in the rock mass around the borehole during the combustion stage of gas producing tool；the detonation stage occurs when the pressure reaches the strength of the pressure-sensitive material，due to the combined action of shock wave，stress wave and explosive gas，the near field crushing，mid field fracturing and far field vibration of the roof are caused. The damage characteristic area of roof weakened by gas producing tool fracturing technique is compared with blasting fracturing technique，the crushing zone radius is decreased by about 22%，the fracture zone radius is increased by about 23%，and damage zone radius is increased by about 5%，compared with hydraulic fracturing technique，the crushing zone radius is increased by 133%，the fracture zone radius and damage zone radius are reduced，but the damage uniformity is significantly improved. The gas production tool is suitable for stable roof with less joint cracks，which can give full play to the effect of high-pressure gas，which is positively correlated with the strength of pressure-sensitive materials and the length of primary cracks，and negatively correlated with the initial confining pressure of rock mass. Combined with the field test results，the effectiveness and superiority of the gas producing tool weakening hard roof are verified.
杜 建1，左建平1，2，吴根水1，赵善坤3. 产气具弱化坚硬顶板力学机制及损伤特征分析[J]. 岩石力学与工程学报, 2023, 42(9): 2224-2236.
DU Jian1，ZUO Jianping1，2，WU Genshui1，ZHAO Shankun3. Analysis of mechanical mechanism and damage characteristics of new fracturing device gas producing tool weakening hard roof. , 2023, 42(9): 2224-2236.
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2023, Vol. 42 
