煤层群重复采动下被保护层卸压瓦斯渗流规律实验研究

发布时间：2018-06-21 18:07

本文选题：煤层群 + 上保护层　；参考：《西安科技大学》2017年硕士论文

【摘要】：随着煤层开采向深处发展,煤层具有的低渗透性、高瓦斯压力和高地应力严重增加了卸压开采难度,降低了瓦斯抽采效果,而保护层是增透卸压提高瓦斯抽采效果主要方法之一。本文主要针对近距离煤群瓦斯涌出矿井开采,运用理论分析、相似材料物理模拟实验和数值模拟相结合的研究方法,系统的研究了在上保护层重复开采条件下被保护层多重增透卸压后的瓦斯渗流变化规律。通过自主设计实验系统和实验方法,开展相似材料物理模拟实验,并结合采动对渗流影响的理论分析,得出保护层开采过程中被保护层瓦斯渗流呈现规律性变化,对实验结果处理分析得出:走整个走向上渗透率变化曲线呈驼峰状,在推进过程中渗透率均经历降低、升高、降低、趋于平稳的过程,且随着保护层数增加,与被保护层的层间距变小,被保护层的渗透率越大。通过采用FLAC3D数值模拟软件,建立多层上保护层重复采动三维数学模型,模拟得出不同保护层开采过程中被保护层的卸压特性以及底板破坏程度,在保护层开采完全稳定后,卸压曲线呈现与渗透率变化曲线相反的驼峰状,开采多层保护层,被保护层卸压更充分,底板破坏越深、破坏程度越大。结合数值模拟和物理相似模拟,根据走向上底板应力变化规律,得出在底板不同应力区域内的渗流变化规律,得出被保护层渗流呈区域性变化,其中应力集中区减渗减流,卸压膨胀区增透增流,应力恢复区减渗减流且渗流大于原始应力区,并得出随着保护层层数的增加影响渗流的主要原因。为优化卸压瓦斯抽采系统布置,使煤层增透卸压,提高卸压效果和瓦斯抽采率提供一定理论依据。
[Abstract]:With the development of coal seam mining, the coal seam has low permeability, high gas pressure and high ground stress seriously increase the pressure relief mining difficulty, and reduce the gas drainage effect. The protective layer is one of the main methods to improve the gas drainage effect. In this paper, aiming at the coal gushing out of the coal mine in the near distance, the research method of the combination of theoretical analysis, physical simulation experiment of similar material and numerical simulation is used. The variation law of gas seepage under the condition of repeated mining in the upper protective layer after multiple antireflection and pressure relief of the protective layer is systematically studied in this paper. Through the independent design of experimental system and experimental method, the physical simulation experiment of similar materials is carried out, and the theoretical analysis of the influence of mining on seepage flow is combined, and it is concluded that the gas seepage of protected layer presents regular changes during the mining process of protective layer. The analysis of the experimental results shows that the permeability change curve of the whole strike is hump, and the permeability decreases, increases, decreases, and tends to steady in the course of propulsion, and with the increase of the number of protective layers, The smaller the interval between the protected layer and the protected layer, the greater the permeability of the protected layer. By using FLAC3D numerical simulation software, the 3D mathematical model of repeated mining of multi-layer upper protective layer is established. The pressure relief characteristics of the protective layer and the damage degree of the bottom plate in the mining process of different protective layers are obtained by simulation. After the mining of the protective layer is completely stable, The pressure relief curve presents the hump shape contrary to the permeability change curve. When the multi-layer protective layer is mined, the pressure relief of the protected layer is more fully, the deeper the damage of the bottom plate is, the greater the damage degree is. Combined with numerical simulation and physical similarity simulation, according to the law of stress variation of strike upper floor, the law of seepage flow variation in different stress regions of bottom plate is obtained, and regional variation of seepage flow in protected layer is obtained, in which seepage reduction and flow reduction in stress concentration area are obtained. The seepage in the stress recovery area is larger than that in the original stress zone, and the main reason for the influence of seepage is obtained with the increase of the number of protective layers. This paper provides a theoretical basis for optimizing the arrangement of pressure relief gas drainage system, making the coal seam anti-permeability and pressure relief, improving the pressure relief effect and the gas extraction rate.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712

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