煤与瓦斯突出失稳蕴育过程及数值模拟研究

发布时间：2019-01-20 17:35

【摘要】：煤炭作为我国的主体能源，煤与瓦斯突出事故一直是限制其安全高效开采的因素之一。近年来突出防治技术的发展和煤矿安全需求的增强都对煤与瓦斯突出机理研究提出了更高的要求，以综合假说为基础的定性化认识受限于对针对性、科学化的防突技术指导，对突出机理定量化研究有待加强。本文运用岩石力学、渗流力学、吸附理论等理论方法，基于双重孔隙介质模型建立了煤与瓦斯突出发动之前煤岩—瓦斯演化控制方程，以有效应力、吸附变形及渗透性演化等耦合项来表明瓦斯场—煤岩应力应变场之间相互作用，，并通过突出能量条件来表征突出倾向性，分析了瓦斯、地应力、煤体力学性质对突出能量的影响及突出能量分布和演化对突出蕴育、失稳的控制作用。研究获得的结论主要在以下几个方面。（1）煤中微孔是控制煤体吸附性能的主要因素。在煤孔隙孔径较小时（气体分子直径量级）孔壁吸附势会发生重叠，对瓦斯吸附力增强，在很小压力下即可达到吸附饱和，即减小了Langmuir压力。因此，不仅是煤最大吸附能力，Langmuir压力同样受微孔发育影响，特别是孔径较小的微孔。由于变质程度增加煤中微孔发育，Langmuir压力随煤阶提高呈下降趋势。（2）根据屈服煤体峰后渗透性随软化模量增长规律，结合双重孔隙介质渗透性模型建立了采掘过程中扰动煤体的渗透性演化方程。对采掘后前方煤体渗透性进行的研究表明，采掘扰动后煤体渗透性具有分区分布特性，从煤层深部原始地带至煤壁渗透性依次经过降低区、升高区和骤增区，其分区分布特征是与煤体应力分带分布形成机制密切相关的。由于渗透性分区性，煤层瓦斯分布也具有分区特点，煤壁附近高渗低压煤体构成了防止煤体瓦斯突出的安全带。之后分析了不同赋存形式瓦斯对煤体变形破坏的影响，除游离瓦斯对煤体受力有孔隙压力的影响外，煤中吸附态瓦斯的变化也会改变煤体受力状态，影响到煤体的屈服破坏，排放瓦斯后煤体强度的增加能降低突出发生的危险性。（3）大型突出案例表明突出地点往往具有瓦斯局部异常，富存了大量瓦斯。而富集区周边存在环状低渗带是瓦斯得以长期保存的一个条件。在化简为一维流动模型后，进一步分析表明低渗带渗透性大小及宽度是影响高压瓦斯保存的主要因素。低渗带内存在的高瓦斯压力及压力梯度使得进入低渗带后突出可能性大大增强，所保存的高压瓦斯能够为突出灾害提供巨大的能量，形成了大型突出的条件。（4）煤体强度破坏及煤—瓦斯系统积聚能量超过其储存能力是系统失稳发动突出的条件，因此可以通过突出潜能积聚程度来分析煤体突出危险性。基于此，提出了以突出发动潜能与突出发动过程耗能之比作为失稳判据判断突出倾向性。并通过分析煤体突出发动潜能的积聚形式及发动过程耗散途径，建立了相应的计算公式。（5）瓦斯、地应力及煤体力学性质等突出因素是突出能量的主要影响因素。瓦斯条件是突出发动能量积聚的主要影响因素，煤层所受构造应力同样对突出能量积聚有重要影响，增加了煤体突出倾向。煤体力学性质对突出影响主要表现为煤体强度及破碎功的影响。（6）通过突出模拟实验验证了瓦斯及应力荷载是煤体突出潜能的主要来源，对突出能否发动及突出规模具有决定作用。另外，可通过不同突出潜能实验条件，根据其突出发动情况，获得煤体失稳突出所需的能量，从而对煤—瓦斯系统能量保持能力进行研究。（7）井下开采过程中由于煤层条件非均性，采掘面前方破坏区煤体突出潜能及能量储存能力的分布也是随煤层条件而变化的。在遭遇低透气性、高瓦斯、高应力、构造煤等条件时，破坏区煤体积聚能量超出其能量储存能力，系统能量处于不平衡状态，释放能量从而造成突出，因此突出能量分布及其演化对突出的发生具有控制作用。
[Abstract]:As the main source of energy in China, coal and gas outburst have been one of the factors restricting the safe and efficient exploitation of coal. In recent years, the development of the prevention and control technology and the enhancement of the coal mine safety demand have put forward higher requirements on the research of coal and gas outburst mechanism, and the qualitative understanding based on the comprehensive hypothesis is limited to the guidance of the targeted and scientific anti-process technology. The quantitative research on the protruding mechanism is to be strengthened. In this paper, based on the theory of rock mechanics, seepage mechanics and adsorption theory, the gas evolution control equation of the coal and gas outburst before the coal and gas outburst is established based on the double porosity medium model, so as to have the effect The coupling terms, such as force, adsorption deformation and permeability evolution, are used to indicate the interaction between the stress and strain fields of the coal rock in the gas field, and the outburst tendency is characterized by the protruding energy conditions, and the gas and ground should be analyzed. The Effects of the Force and the Physical and Physical Properties of the Coal on the Protruding Energy and the Control of the Protrusion and the Instability of the Protruding Energy Distribution and the Evolution The conclusions obtained by the study are mainly in the following Surface. (1) The micro-pores in the coal are the main to control the adsorption performance of the coal body. in that event that the pore diameter of the coal pore is small (on the order of the diameter of the gas molecule), the adsorption potential of the pore wall is overlapped, the adsorption force of the gas is enhanced, and the adsorption saturation can be reach under a very small pressure, i. e., the Langmui is reduced, r pressure. Therefore, not only is the maximum adsorption capacity of the coal, the Langmuir pressure is also affected by the development of the micro-pores, especially the pore diameter is small. The pressure of the Langmuir increases with the increase of the order of the coal, due to the increase of the degree of deterioration of the microwell in the coal. (2) According to the increase of the permeability with the softening modulus of the yielding coal body, the penetration of the disturbed coal in the mining process is established in combination with the permeability model of the double pore medium. The study of the permeability of the coal body in front of the mining shows that the permeability of the coal body after the mining disturbance has the characteristics of the partition distribution, and the permeability of the coal body from the deep original zone to the coal wall permeability of the coal seam successively passes through the reduction zone, the elevation and the permeability of the coal body, The partition distribution of the zone and the surge zone is the mechanism of the distribution of the distribution of the coal body's stress. It is closely related that the gas distribution of the coal seam has the characteristics of partition due to the permeability zoning, and the high-permeability and low-pressure coal body in the vicinity of the coal wall forms the gas outburst prevention of the coal body. The influence of the different occurrence forms of gas on the deformation and failure of the coal body is analyzed. In addition to the influence of the free gas on the pore pressure of the coal body, the change of the adsorbed gas in the coal can change the stress state of the coal body and affect the coal body. the increase of the strength of the coal body after the discharge of the gas can be reduced and the yield of the coal body can be reduced, the danger of being born. (3) The large-scale highlight case indicates that the prominent place often has a partial gas anomaly, A large amount of gas is stored in the rich area. The annular low-permeability zone around the rich area is a long-term gas. The results show that the permeability and the width of the low-permeability zone are the influence of the high-pressure gas after the simplification of the one-dimensional flow model. The main factor of preservation is that the high gas pressure and pressure gradient present in the low-permeability zone make the possibility of the projection to be greatly enhanced after entering the low-permeability zone, and the stored high-pressure gas can provide great energy for the outburst disasters and form The condition of large-scale projection. (4) The strength of the coal body and the accumulation energy of the coal-fired gas system exceed the storage capacity of the system, which is the condition of the system's instability, so that the accumulation of the protruding potential can be achieved. The outburst risk of the coal body is analyzed. Based on this, the ratio of the energy consumption of the protruding launching potential and the protruding starting process is used as the instability. Based on the analysis of the accumulation form of the protruding potential of the coal body and the way of dissipation of the starting process, the paper The corresponding calculation formula is established. (5) The prominent factors such as gas, in-situ stress and physical and physical properties of coal are the main factors. The main influencing factors of the outburst energy are that the gas condition is the main influencing factor of the energy accumulation of the outburst, and the structural stress of the coal seam also plays an important role in the accumulation of the protruding energy. in response, that tendency of the coal body to protrude is increase. the physical and physical properties of the coal are mainly manifested by the prominent effect. The influence of the strength of the coal body and the breaking work of the coal body is verified. (6) The main source of the protruding potential of the coal body is verified by the projection simulation experiment, and can the outburst be in addition, that energy required for the instability of the coal body can be obtain through the experimental conditions of different protruding potential, The energy conservation capability of the system is studied. (7) In the process of underground mining, due to the non-uniformity of the condition of the coal seam, the protruding potential of the coal body and the energy storage energy of the coal body in the front of the excavation The distribution of the force is also changed with the condition of the coal seam. When the conditions such as low air permeability, high gas, high stress and structural coal are encountered, the energy of the coal in the damaged area exceeds its energy storage capacity, and the energy of the system is not the equilibrium state, the release of energy,
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TD713

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