瓦斯抽采二次膨胀封孔材料膨胀机理及应用研究

Study on expansion mechanism and application of double-expansive material for borehole sealing in gas drainage

为降低瓦斯抽采漏气,开发了1种具备后期膨胀的二次膨胀材料(DE),以水泥基材料为对比样,利用自制的膨胀力测试装置,以XRD和SEM分别表征其膨胀力及微观结构。研究结果表明:相比水泥基材料,DE材料的膨胀力明显,并表现出显著的时间效应,且DE材料的膨胀力随约束刚度增大而增大;水化1 d时,DE材料较水泥基材料生成更多的钙矾石(AFt)晶体;随着DE材料水化,AFt晶体不断增多,且水化7 d后AFt晶体发生延迟膨胀,这是引起DE材料后期膨胀的主要因素;工程应用表明DE材料可提高瓦斯抽采浓度及纯量,有效改善抽采效果。

To reduce the air leakage of gas drainage,a double-expansive(DE)material with the later expansion was developed.Taking the cement-based material as the contrast sample,the expansive force and microstructure of the DE material were characterized with X-ray diffraction(XRD)and scanning electron microscopy(SEM)respectively by using the self-developed testing device of expansive force.The results showed that the expansive force of the DE material was obvious compared with the cement-based material,with a significant time-dependent effect,and it increased with the increase of constraint stiffness.After the hydration for one day,the DE material generated more ettringite(AFt)crystal compared with the cement-based material.Along with the hydration of the DE material,the AFt crystal increased over time and occurred the delayed expansion after the hydration for seven days,which was the main factor causing the later expansion of the DE material.The engineering application showed that the DE material could increase the concentration and pure quantity of gas drainage,and improve the drainage performance effectively.