采动煤层瓦斯充分卸压应力判别指标理论研究

针对高瓦斯低透气性煤层群瓦斯卸压抽采时,瓦斯充分卸压范围的确定问题,运用断裂损伤力学理论,分析了煤岩层卸压过程中应力应变关系,提出以应力卸压比（卸压后应力值/原岩应力值）作为煤层是否充分卸压的判别指标;并结合阳泉矿区高瓦斯煤层赋存条件,对应力卸压比作为判别指标的可行性以及煤层充分卸压时应力卸压比的影响因素进行了研究。结果表明：阳泉三矿3号煤理论计算充分卸压时卸压比为0.445,与实际吻合。充分卸压时的应力卸压比与被保护煤层埋深有关,埋深越大,卸压比越小;埋深100～500 m时,应力卸压比变化较大,而埋深大于500 m时,应力卸压比变化缓慢。

Theoretical Study on Stress Distinguishing Index of Gas Pressure Fully Released in Mining Seam

According to the setting problems of the gas pressure fully released scope during the gas drainage and gas pressure releasing period in the high gassy and low permeability seam group,the fracture failure mechanics theory was applied to analyze the stress and strain relationship in the pressure releasing process of the seam and strata.The stress and pressure releasing ratio(the stress value after the pressure released/the in-situ rock stress value) was proposed to be the index to distinguish the pressure fully released or in the seam.In combination with the deposit conditions of the high gas seam in Yangquan Mining Area,a study was conducted on the feasibility of the stress and pressure releasing ratio as the distinguishing index and the influence factors of the stress and pressure releasing ratio when the seam pressure fully released.The results showed that with the theoretical calculation of No.3 seam in Yangquan No.3 mine,the pressure releasing ratio when the pressure fully released was 0.445 and could meet the actual data.The stress and pressure ratio when the pressure fully released would be related to the depth of the protected seam and the deeper depth,the smaller the pressure released ratio would be.When the depth was 100~500 m,the variation of the stress and pressure released ratio would be high.And when the depth was over 500 m,the variation of the stress and pressure released ratio would be gently.