【作者】 魏明尧；

【导师】 王恩元；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2013， 博士

【摘要】 含瓦斯煤层的动力灾害主要包括煤与瓦斯突出和冲击地压，动力灾害发生后会摧毁巷道等采掘空间，并伴随着瓦斯涌出异常，严重威胁着煤矿安全高效生产和矿山工作人员的生命安全。含瓦斯煤层动力灾害发生时应力场和瓦斯渗流场是相互影响的，因此研究含瓦斯煤层应力场和瓦斯场的气固耦合效应对进一步揭示动力灾害机理及预防动力灾害发生有着十分重要的作用。本文利用理论建模和数值模拟手段系统研究了煤层应力与瓦斯渗流的耦合规律，主要得到以下结论：（1）根据煤体结构特点，采用双重孔隙结构模型描述煤体的多孔基质和裂隙结构特征。分析了煤体基质在应力作用下的压缩变形规律，得到了基质系统孔隙率、渗透率与应力的变化关系；分析了裂隙受压缩而闭合和受剪切而张开的规律，并采用分形理论建立了裂隙开度与应力的变化模型，在此基础上建立了三维空间裂隙系统的孔隙率、渗透率与复杂应力场的关系。（2）分析了受裂隙作用形成的煤体部分分割和部分连接的特殊结构，得到了瓦斯吸附膨胀或解吸收缩应变对煤体连接部分的有效应力的影响，并在此基础上建立了在瓦斯吸附膨胀或解吸收缩应力作用下的含瓦斯煤体有效应力方程。采用体积应变量衡量裂隙煤体的损伤程度，建立了煤体的损伤演化方程；采用Mohr-Coulomb屈服准则作为判断破坏的依据，并分别对剪切破坏和拉伸破坏后的应变量进行塑性修正；同时分析了煤体粘聚力随应变增加而降低的特征，采用煤体粘聚力应变软化模型表征煤体的应变软化特征。（3）根据瓦斯气体的渗流规律和状态方程，分别建立了基质系统和裂隙系统内瓦斯气体的质量守恒方程。基于TOUGH2多相流模拟软件开发了TOUGH2(CH4)瓦斯渗流模拟软件，模拟分析了煤样内瓦斯渗流过程，验证了本软件的合理性；采用C++语言编写了煤体损伤本构模型的dll库文件，通过FLAC3D软件对煤体单轴压缩过程进行了模拟，其结果准确的反映了煤体的损伤破坏过程。应力场对渗流参数产生影响，同时瓦斯渗流场对煤体有效应力产生影响，结合渗流参数与应力关系和煤体有效应力方程即构成了气固耦合模型。根据建立的气固耦合模型，开发了TOUGH2(CH4)-FLAC气固耦合数值模拟软件，并模拟分析了有围压加载时煤体内瓦斯渗流规律，模拟结果与理论结果相符。根据模拟结果可以证明本文提出的气固耦合模型和数值计算方法具有一定的可靠性。（4）以鹤岗南山矿为工程背景，将开发的TOUGH2(CH4)-FLAC软件应用于现场，对巷道围岩损伤演化和瓦斯渗流情况进行了模拟研究，得到了围岩受冲击扰动前后的损伤特征和瓦斯渗流规律，揭示了冲击扰动造成瓦斯涌出异常的机理。研究成果对深入认识含瓦斯煤层动力灾害机理、制定预防措施等具有重要的意义，同时煤层气固耦合程序的应用为进行煤层瓦斯渗流规律分析提供了一种研究方法。更多还原

【Abstract】 Rockburst in coal seam containing methane is a kind of complex and dynamicdisaster, and it hinders the mine safely that is a big problem for coalmine. The stressfield and the seepage field of methane react upon one another in the process ofrockburst, thus it is important to research the coupling effect between stress field andseepage field to reveal the mechanism of rockburst in coal seam containing methane.This dissertation focuses on the law of failure and deformation of coal and seepage ofmethane. According to the seepage theory for methane and damage mechanics theoryfor coal, the coupling mechanism is investigated by using theoretical modeling andnumerical simulation. The main results are listed as following.(1) The dual-porosity model is applied to describe the characteristic of porousmatrix and fracture structure in coal based on the feature of coal structure. On thebasis of deformation characteristics of coal matrix under stress, the couplingrelationships for both porosity and permeability with stress are built. The law ofclosure of fracture under compression and dilation under shearing are analyzed basedon the structure characteristics of single fracture in fracture system. In addition, thedeformation model of fracture is built, and then the coupling relationships for bothporosity and permeability with stress in fracture system are obtained based on thecubic law.(2) The swelling and shrinkage strain induced by methane adsorption anddesorption are obtained according to the theory of physical chemistry of coal surfaces.The swelling and shrinkage strain have a strong effect on the effective stress due tothe particular structure of coal matrix separated by fracture. Effective stress equationfor coal containing methane is built which considering the influence of swelling andshrinkage stress. Since volumetric strain describes the development of fracture,damage evolution equation for coal is built by accounting volumetric strain as aninternal factor. Mohr-Coulomb failure criterion is adopted as criterion of criticaldamage. Then the strain is corrected through plastic corrections after shear failure ortensile failure occurs. Meanwhile, strain-softening model for cohesion of coal is builtby analysis of the characteristic of cohesion decreasing with the increase of strain.(3) Equations of mass conservation for methane in both matrix system andfracture system are built based on the seepage pattern and equations of states.Numerical simulation software named TOUGH2(CH4) for methane seepage is developed by rewriting the code of TOUGH2. Then the rationality of this software isverified by a small simulation of methane seepage in coal sample. The damage modelfor coal is written in C++, and compiled as a DLL file that can be loaded by FLAC3Dwhen it runs. The process of coal sample under compression is simulated based onFLAC3D with loading the new defined model. The simulated result reflects reality ofdamage process of coal accurately. In order to run a coupled simulation for theanalysis of gas-solid coupling, TOUGH2(CH4) and FLAC3D simulation arecollaborated as TOUGH2(CH4)-FLAC with TOUGH-FLAC code which is a coupledcode linking two existing simulators (TOUGH2and FLAC3D). The accuracy of newcoupling simulator is proved by a numerical model for calculation of methane seepagein coal sample under confining pressure.(4) TOUGH2(CH4)-FLAC is implemented into a field case in Hegang-Nanshancoal mine. The simulations focus on the damage evolution of surrounding rock andmethane seepage. The simulation results reveal the mechanism of extreme gasemission after disturbance induced by rockburst.更多还原