煤与瓦斯突出层裂发展机制研究

发布时间：2018-04-05 22:30

  本文选题：煤与瓦斯突出　切入点：层裂　出处：《中国矿业大学》2014年博士论文

【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。
[Abstract]:Coal and gas outburst is the instability failure of gas-bearing coal body under the combined action of stress and gas.In the process of outburst, the crack of coal body expands and is stripped and broken and thrown into the excavation space.Therefore, the internal mechanism of outburst development should be studied to lay a theoretical foundation for preventing coal and gas outburst.In this paper, the adsorption / desorption law of gas-bearing coal is studied by means of surface physical chemistry, rock mechanics, seepage mechanics and similarity theory.Under the coupling of stress field gas field and temperature field the constitutive relation and permeability evolution law were studied. The outburst simulation test was carried out and the development mechanism of outburst spallation was studied and some innovative results were obtained.The main conclusions of this paper are as follows:The adsorption law of 10 coal at different temperatures in Wolong Lake Coal Mine is studied experimentally. It is found that the adsorption constant a does not change with the temperature, and the adsorption constant b changes with the change of temperature.A large number of experiments on desorption of coal particle gas under isothermal conditions have been carried out. The desorption amount and the square root of time accord with the equation of Langmuir form.The whole stress-strain process of coal body is simplified into four stages: linear elasticity, nonlinear elastoplasticity, brittle drop and ideal plasticity. The permeability evolution is simplified as the permeability decreasing section and the permeability increasing stage.The stage of rapid increase of permeability and the period of constant permeability.The internal structure of coal body fracture is studied. It is concluded that only part of the expansion deformation of coal matrix acts on coal body fracture. The influence factor f m of the expansion deformation of coal matrix on fracture deformation is put forward, whose value is between 0 and 1.The constitutive equation of gas-bearing coal body considering adsorption deformation, thermal expansion deformation and effective stress is established.Based on this, the permeability models of linear elastic stage and plastic stage of gas-bearing coal body are established.Based on the similarity criterion, a true triaxial coal and gas outburst simulation test system is designed. Its performance parameters are gas pressure 鈮

本文编号：1716781