【作者】 郭品坤；

【导师】 程远平；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2014， 博士

【摘要】 煤与瓦斯突出是含瓦斯煤体在应力和瓦斯的综合作用下发生的失稳破坏。突出过程中，煤体裂隙扩展、被剥离破碎抛向采掘空间。因此需对突出发展的内在机制进行研究，为防治煤与瓦斯突出奠定理论基础。本文运用表面物理化学、岩石力学、渗流力学和相似理论等多学科理论，采用理论和实验相结合的方法，研究了含瓦斯煤体的吸附/解吸规律、应力场-瓦斯场-温度场耦合作用下的本构关系和渗透演化规律，开展了突出模拟试验，研究了突出的层裂发展机制，并取得了一定的创新成果。本文的主要研究结论如下：实验研究了卧龙湖煤矿10煤的不同温度条件下的吸附规律，得出其吸附常数a不随温度变化，吸附常数b随温度的变化而改变。开展了大量的等温条件下煤粒瓦斯解吸实验，解吸量与时间的平方根之间符合Langmuir形式的方程。将煤体全应力应变过程简化为线弹性、非线性弹塑性、脆性跌落和理想塑性4个阶段，渗透率演化对应简化为渗透率减小段、渗透率增加段、渗透率快速增加阶段和渗透率不变段。研究煤体裂隙的内部结构，得出煤基质的膨胀变形仅有部分作用于煤体裂隙，提出煤基质膨胀变形对裂隙变形的影响因子f m，其值介于0~1之间。构建了考虑吸附变形、热膨胀变形和有效应力作用的含瓦斯煤体本构方程。基于此建立了含瓦斯煤体线弹性阶段和塑性阶段的渗透率模型。基于相似准则，设计了真三轴煤与瓦斯突出模拟试验系统，其性能参数为：瓦斯压力≤10MPa，地应力≤27MPa，温度在室温至60℃范围内变化。开展了煤与瓦斯突出相似模拟试验。以模拟试验条件为基础，建立了考虑瓦斯拉裂破坏、吸附膨胀变形和吸附对煤体强度影响的突出层裂发展模型。解算突出层裂发展模型，研究了瓦斯压力、吸附能力、断裂韧度和渗透率对突出发展的影响规律。突出是一个快速的动力过程，模拟得出其发展时间一般在1.68s。其发展过程大致可分为突出发展的加速期、稳定期和衰减期。突出发动后，在高压瓦斯和瓦斯压力梯度作用，煤体被快速破坏。此时煤体的瓦斯压力梯度最大，煤体破坏产生的层裂的厚度较小。进入稳定期，突出面前方煤体的压力分布、破裂速度基本稳定。瓦斯压力梯度区的宽度平均为7.33cm；瓦斯压力梯度平均为8.215MPa/m。破裂速度从0.4s的1.32m/s上升至0.9s的1.54m/s。突出向内部发展的速度约为0.15193m/s。随着突出的发展，未被剥离煤体中的瓦斯压力和梯度逐渐减小，层裂的厚度逐渐增大，最终瓦斯耗尽，突出终止。更多还原

【Abstract】 Coal and gas outburst is the unstable failure of coal containing gas under thecombined influence of stress and gas. The fracture expands and the coal is strippedand threw out into the mining space in the process of outburst. Therefore, it needs tostudy the mechanism of coal and gas outburst propagation in order to establishtheoretical basis for preventing and controlling the coal and gas outburst.The theories of Rock mechanics, Physical Chemistry, Fluid mechanics andSimilarity theory, combining the theoretical analysis and laboratory experiment wereemployed to research in this dissertation. The adsorption/desorption regularities,constitutive relations and permeability evolution of gas-saturated coal under couplingbetween stress-gas-temperature were studied. The similar experiments of coal and gasoutburst were conducted. And then the laminar spallation mechanism of outburstpropagation was studied based on the condition of experiment. There are someinnovations in the dissertation. The main conclusions are listed as below:The adsorption constant a doesn’t change with the temperature, but theadsorption constant b changes drawn from the adsorption experiment of coal samplesfrom No.10coal seam in Wolonghu coal mine. The relationship between the gasdesorption quantity from coal particle and the square root of time under the isothermalconditions complies with the form of Langmuir equation.The complete stress-strain progress and the evolution of permeability through theprogress can be simplified into four stages: Linear elastic stage (permeabilitydecrease); Nonlinear elastic-plastic stage (permeability increase); Drop brittle stage(permeability increase rapidly) and Ideal plastic stage (permeability stabilizes).Consider a cube build a physical model of the internal structure of coal fracture, onlya portion of the coal matrix swelling deformation has effects on coal fracture basingon the structural analysis of coal fracture. The impact factor of coal matrix swellingdeformationf m(0＜f m＜1) was brought forward to demonstrate the effects of coalmatrix swelling deformation on fracture. And the corresponding constitutive equationsand permeability evolution equation were established under the condition of couplingmulti-fields (stress field, gas field and temperature field).Based on the similarity criteria, a truly triaxial experiment system simulatingcoal and gas outburst was designed and manufactured. The main parameters of systemare: gas pressure≤10MPa; ground stress≤27MPa; temperature from room temperature to60℃. Similar experiments of coal and gas outburst were carried out. Based on theconditions of experiments, a laminar spallation model of outburst propagation wasestablished, in which effects of tensile fracture due to gas expanding, swelling andstrength reducing caused by sorption were solved. The influences of gas pressure,absorptivity, fracture toughness and permeability of coal on the outburst propagationwere investigated by solving the established outburst model in different conditions.The outburst is a fast dynamic process, of which the propagation time is1.68s onaverage obtained by model study. The process of outburst propagation could bedivided into three stages, which are acceleration period, stable period and decayperiod. After the trigger of outburst, the coal is rapidly destroyed by the effect of largegas pressure and its gradient. Because of the largest gas pressure gradient, thethickness of the spherical shell produced by coal breakage is small at this time. Thepressure distribution and burst velocity on the front of outburst face are basicallystable. The width of zone of gas pressure gradient is7.33cm on average and thegradient is8.215MPa/m on average. The split velocity increases from1.32m/s intime of0.4s to1.54m/s in0.9s. The propagation velocity of outburst is about0.15193m/s.The gas pressure and its gradient in the unbroken coal gradually decrease withthe outburst propagation leading the gradually increase of the coal laminationthickness. At last the outburst stops due to gas out of store.更多还原