【作者】 刘洪永；

【导师】 程远平；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2010， 博士

【摘要】 经过多年的科学研究和工程实践证明,采动卸压瓦斯抽采技术是防治煤与瓦斯突出、降低煤层瓦斯含量最有效、最经济的区域性措施。尽管近几十年来开展了大量的采动卸压瓦斯抽采现场试验,但对采动煤岩体变形与卸压瓦斯瓦斯流动相互作用的研究尚不够成熟,还无法为卸压瓦斯的高效抽采提供理论基础和技术支持。本文以远程采动煤岩体为研究对象,运用岩石力学、采矿工程、渗流力学、数值仿真等理论,采用现场实验、实验室相似模拟、理论分析和数值分析相结合的研究方法,系统研究了采动煤岩体的卸压特征、移动变形、采动应力变化及卸压瓦斯流动规律;开展了采动煤岩体变形与瓦斯流动耦合作用研究,构建了采动煤岩体弹脆塑性本构模型和采动煤岩体变形与瓦斯流动耦合动力学模型及数值计算方法,通过模型的应用初步获得了远程上被保护层应力场、位移场与渗透率的时空变化规律,最后提出了保护层开采工程分类及判定方法,以及远程保护层开采及卸压瓦斯抽采技术体系,并在阳泉新景矿成功地进行了试验,取得了显著的抽采效果。本文为保护层开采设计及远程被保护层卸压瓦斯的高效抽采提供了理论依据和技术支持。论文主要研究内容及成果有:1)利用平面应变相似模拟实验系统,以阳泉矿区新景矿为地质背景,开展了远程采动煤岩体裂隙演化相似模拟试验研究,获得了远程被保护层采动应力、裂隙发育和变形的时空演化规律;2)基于Drucker-Prager准则,引入理想弹脆塑性模型和内切圆准则,构建了采动煤岩弹脆塑性损伤本构模型及数值格式,采用VC++2005将其开发成FLAC3D能够调用的模型,并开展了模型验证与应用,为采动煤岩体变形的研究提供了本构模型;3)构建了反映采动裂隙、离层对瓦斯流动影响的非线性卸压瓦斯流动方程——广义幂定律,为采动煤岩体卸压瓦斯流动提供了控制方程;4)构建了适合高强度开采条件下低渗透性煤岩体变形与瓦斯流动特点的采动煤岩变形与瓦斯流动气固耦合动力学模型;利用COMSOL Multiphysics多物理场耦合软件平台实现了模型的验证与应用,初步获得了远程下保护层上覆岩应力场、位移场与渗透率的时空变化规律;5)提出了综合考虑煤层赋存条件、层间硬岩以及保护层工作面回采参数等影响因素的保护层工程分类及判定方法,以当量相对层间距为指标对上、下保护层进行了分类;6)提出了远程保护层开采及卸压瓦斯抽采技术体系,并在阳泉新景矿成功地进行了试验,取得了显著的抽采效果。保护范围内被保护层综合瓦斯抽采率达到了70.1%,瓦斯含量由18.17降至5.4m3/t,有效地消除了3#煤层的煤与瓦斯突出危险性,实践验证了采动煤岩变形与瓦斯流动气固耦合模型的合理性和可行性。更多还原

【Abstract】 The pressure-relief gas drainage technique is the most effective and economical regional method to decrease gas content and eliminate coal and gas outburst from many years’practices and studies. In recent decades, many field tests was operated on pressure-relief gas drainage due to mining, however, the interaction between the deformation and pressure-relief gas flow of coal and rock mass is not considerate enough to provide the theory and method for efficient pressure-relief gas drainage. By taking coal and rock mass due to mining as the research object in the paper, the combination methods of laboratory experiment, filed experiment, theoretical analysis and numerical analysis are used to research on mechanical characteristic, movement, deformation, pressure relief and seepage characteristic of overlying coal and rock masses. The paper carried on the interaction between the deformation and pressure-relief gas flow, and then set up elasto-brittle- plastic constitutive model of coal rock mass damage due to mining and fully coupled model and numerical solution for deformation and pressure-relief gas flow. The research provides theoretical basis and reference for the design of protective layer mining and relief-pressure gas drainage. The main aspects can be seen as the following:1) A similar experiment for fissure evolution of remote coal and rock mass due to mining, obtained the space-time change law of mine-induced stress, fracture development and deformation in the remote protected layer.2) The elasto-brittle- plastic constitutive model of coal rock mass damage due to mining was set up based on the plastic flow format of Drucker-Prager constitutive model by introducing the inscribed circle criterion and the ideal brittle-plastic model, and validated by comparing with the traditional constitutive models through uniaxial and triaxial compression numerical tests.3) Considering the nonlinear characteristics of the pressure-relief gas flow effecting by the mine-induced fracture and separation, the generalized power law was set up to study the pressure-relief gas migration, depending on the local Reynolds number.4) A fully coupled model and numerical solution for deformation and pressure-relief gas flow were established to simulate the low-permeability coal and rock mass under high-strength underground mining. Then the correctness and rationality of this model was validated by COMSOL Multiphysics software, through the simulation of single borehole gas drainage and three boreholes gas drainage.5) The classification and judgment method of the protective layer was brought out by the equivalent relative interval between the protective layer and the protected layer, considering the occurrence condition and mining parameters of the protective layer working face and the effluence of hard rock in the overburden. The under protective layer is classified into three kinds, and the upper protective layer two kinds.6) A technical system was brought out of pressure-relief gas drainage for the protective layer and the protected layer. The chosen methods were successfully applied in Xinjing coal mine of Yangquan coal field, and the relieved gas in the remote protected layers was better drained utilizing the mining influence of the protective layer, which validates the fully coupled model for deformation and pressure-relief gas flow.更多还原