瓦斯抽采钻孔封孔水泥浆液水灰比优化研究

Study on optimization of water-cement ratio of the cement grout for sealing boreholes in gas drainage

为进一步提高本煤层瓦斯抽采钻孔封孔模拟的准确性,考虑水泥浆液扩散过程中黏度时变性及应力对浆液扩散造成的影响,对不同水灰比条件下的水泥浆液基本性能进行实验室测定,分析了不同水灰比的水泥浆液性能及变化特点。采用理论推导、数值模拟的方法,对不同水灰比条件下的水泥浆液扩散范围开展研究计算,对煤矿井下注浆封孔水泥浆液的水灰比进行了优化。在贵州小屯煤矿对模拟结果进行实测验证,现场封孔效果较好,进一步结合井下实际情况对水泥浆液的水灰比进行优化。研究结果表明:水泥浆液初始动力黏度随水灰比增大而减小,水泥浆液黏度随时间基本呈指数增长;根据井下实际封孔情况并结合模拟结果,确定水泥浆液的最佳水灰比为0.9。

In order to further improve the accuracy of borehole sealing simulation for gas extraction in the coal seam,considering the influence of viscosity time-varying and stress on the grout diffusion during the diffusion of cement grout,laboratory tests were conducted to measure the basic properties of cement grout with different water-cement ratios,and the performance and variation characteristics of cement grout with different water-cement ratios were analyzed.Through theoretical deduction and numerical simulation,the cement grout diffusion range under different water-cement ratios were studied and calculated,and the water-cement ratio for grouting and sealing boreholes in coal mine were optimized.The simulation results in Xiaotun Coal Mine in Guizhou showed that the sealing effect was good,which further optimized the water-cement ratio of cement grout based on the actual conditions of the mine.The results show that the initial dynamic viscosity of cement grout decreases with the increase of water-cement ratio,and the viscosity of cement grout increases exponentially with time;according to the actual sealing borehole situation and the simulation results,the optimal water-cement ratio of cement grout is 0.9.