煤层开采“固-气”耦合相似材料特性分析

Characteristics analysis of“solid-gas”coupling similar materials of coal mining

为研究采动裂隙演化规律,选取适合的“固-气”耦合相似材料,结合岩石力学和流体力学理论,运用自行改进的单轴压力仪及渗透性测试装置,对不同材料配比所制作试件的力学及渗透特性进行研究。最终确定以砂子作为骨料,淀粉及水泥作为胶结剂,水作为溶剂,并对这种原材料组合在不同配比条件下制作试件的力学及渗透性影响因素开展试验研究,以此为依据开展“固-气”耦合物理相似模拟试验,揭示不同覆岩层位瓦斯浓度分布规律。结果表明:最终确定的材料配比组合能够满足岩石力学性能的要求,较原始固相相似模拟材料及“固-气”耦合相似材料PSO(Paraffin石蜡,Sand砂子,Oil油),其渗透速度平均分别下降91.61%及68.29%;通过对新型材料制作出的试件开展力学及渗透特性影响因素试验并进行非线性回归拟合,得出相应变化趋势的拟合方程,同时得到不同淀粉含量对试件抗压强度及渗透性影响趋势的拟合方程。开展二维煤层开采物理相似模拟试验,得到采动覆岩裂隙演化及不同覆岩层位瓦斯浓度分布规律,为进一步开展煤与瓦斯共采多场耦合物理相似模拟试验提供理论依据。

To investigate the evolution law of mining fissures,the suitable“solid-gas”coupling similar materials were selected.Combined with rock mechanics and fluid mechanics theory,the self-improved uniaxial pressure gauge and permeability test device were used to research the permeability characteristics of the test pieces made by different materials.According to the test results,similar materials were obtained with sand as aggregate,starch and cement as cementing agent and water as solvent.And the mechanical and permeability influencing factors of the test pieces produced under different ratios were tested.Based on this,a“solid-gas”coupled physical similarity simulation test was carried out to reveal the gas concentration distribution of different overburden layers.The test results showed that the final combination of materials met the requirements of rock mechanical properties,and the permeability of the material was lower than the original solid phase material“solid-gas”coupling material by 91.61%and 68.29%.The fitting equation of the corresponding trend was obtained based on the test of the influencing factors of mechanics and permeability characteristics of the specimens made by the new materials and the nonlinear regression fitting,and the influence of different starch content on the compressive strength and permeability of the specimens was obtained.The evolution of overburden fissures and the distribution of gas concentration in different overburden layers were obtained by the physical similarity simulation test of two-dimensional coal seam mining.The test results provide a theoretical basis for further conducting multi-field coupled physical similarity simulation tests of simultaneous extraction of coal and gas.