邻近煤层开采下煤岩体结构体系及瓦斯越流规律研究

发布时间：2018-03-13 07:48

本文选题：邻近煤层　切入点：结构简化模型　出处：《河北农业大学》2013年硕士论文　论文类型：学位论文

【摘要】：邻近煤层的开采将会导致采场产生一系列连锁反应，围岩卸压，应力重分布，在围岩中形成应力分区，最终导致岩体损伤，破断，裂隙发育，增大煤岩体的渗透性，进而瓦斯解吸，扩散，渗流等。由于瓦斯突出是煤矿中的一大灾难，因此弄清瓦斯的运移特征将是保证含瓦斯煤安全生产的前提。鉴于此本文以邻近煤层开采为研究对象，综合运用结构力学、岩石力学、流体力学、采矿工程、数值计算等理论，提出了邻近煤层开采围岩结构简化模型，并给出了该结构的内力解析解；研究了邻近煤层开采围岩体应力演化移动变形规律；建立了邻近煤层开采瓦斯越流流固耦合控制方程组，并通过数值计算的方法进行验证，分析邻近煤层中瓦斯的运移规律，为瓦斯防突、瓦斯抽放合理布置钻孔等提供理论依据。论文主要研究内容有：（1）阐述了煤岩体结构的断裂损伤机理及不同部位煤岩体的受力状态，提出了邻近煤层煤岩体采场围岩的结构简化模型，并给出该结构模型受载分布形式及其煤岩体拱结构的内力解析解。（2）基于FLAC~(3D)分析了邻近煤层开采时围岩应力场演化规律，采场顶板围岩的应力分布演化规律，依据采场应力分析了不同区域的受力情况及裂隙发育情况；分析了围岩体积应变和剪应力的分布规律及开采速度对围岩应力分布的影响，，验证了第2章结构模型的合理性。（3）基于构建的煤岩体变形本构方程、瓦斯连续方程、孔隙度及渗透系数的动态演化方程建立了单一煤层及围岩中的瓦斯流固耦合方程、邻近煤层瓦斯越流流固耦合控制方程组。（4）利用COMSOL Muliphisics有限元软件，将邻近煤层越流控制方程组采用固体力学模块、流体力学模块及PDE模式进行数值计算，研究了不同时刻煤层中瓦斯压力、孔隙度、渗透系数的变化规律，分析了开采长度、开采厚度对孔隙度和渗透系数的影响及瓦斯速度场的分布规律。
[Abstract]:The mining of adjacent coal seam will cause a series of chain reaction in the stope, the surrounding rock will be decompressed, the stress will be redistributed, and the stress zone will be formed in the surrounding rock, which will eventually lead to rock mass damage, fracture, crack development, and increase the permeability of coal and rock mass. Gas desorption, diffusion, seepage and so on. Since gas outburst is a major disaster in coal mines, understanding the migration characteristics of gas will be the prerequisite to ensure the safe production of gas-bearing coal. Based on the theories of structural mechanics, rock mechanics, fluid mechanics, mining engineering and numerical calculation, the simplified model of surrounding rock structure in adjacent coal seam mining is put forward, and the analytical solution of the internal force of the structure is given. The law of stress evolution, displacement and deformation of surrounding rock mass in adjacent coal seam mining is studied, and the coupled control equations of gas overflowing and fluid-solid in adjacent coal seam mining are established, and verified by numerical calculation, and the law of gas migration in adjacent coal seam is analyzed. This paper provides theoretical basis for gas outburst prevention and reasonable arrangement of gas drainage drilling. The main contents of this paper are as follows:. 1) the fracture damage mechanism of coal and rock mass structure and the stress state of coal and rock mass in different positions are expounded, and a simplified structural model of surrounding rock in coal and rock mining stope adjacent to coal seam is put forward. The load distribution form of the structure model and the analytical solution of the internal force of the arch structure of coal and rock mass are given. (2) based on FLACU 3D), the evolution law of surrounding rock stress field and the stress distribution of roof surrounding rock in adjacent coal seam mining are analyzed. According to the stress of stope, the stress situation and crack development in different areas are analyzed. The distribution law of volume strain and shear stress of surrounding rock and the influence of mining speed on the stress distribution of surrounding rock are analyzed, and the rationality of the structure model in Chapter 2 is verified. Based on the constitutive equation of deformation of coal and rock mass, the gas continuity equation, the dynamic evolution equation of porosity and permeability coefficient, the gas fluid-solid coupling equation in single coal seam and surrounding rock is established, and the governing equations of gas flowing over flow structure in adjacent coal seam are established. 4) by using COMSOL Muliphisics finite element software, the governing equations of passing flow in adjacent coal seams are numerically calculated by using solid mechanics module, fluid dynamics module and PDE model, and the gas pressure and porosity in coal seam at different times are studied. The influence of mining length, mining thickness on porosity and permeability coefficient and the distribution of gas velocity field are analyzed.
【学位授予单位】：河北农业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TD712

【相似文献】