【摘要】：通過(guò)理論分析、數(shù)值模擬和結(jié)合現(xiàn)場(chǎng)試驗(yàn)的研究方法,對(duì)上保護(hù)層開采條件下下被保護(hù)煤層周圍巖體的應(yīng)力分布、煤層膨脹變形特征和裂隙發(fā)育、煤層透氣性變化規(guī)律及煤層透氣性系數(shù)的優(yōu)化算法進(jìn)行系統(tǒng)的研究,同時(shí)對(duì)煤層底板巖體受力進(jìn)行分析,建立底板巖層沿煤層走向的力學(xué)模型,為了更好地定性和定量地分析底板支承力的分布特征,將模型做相應(yīng)的簡(jiǎn)化,推算出底板應(yīng)力分布的計(jì)算公式,總結(jié)出煤層底板巖層所受應(yīng)力分布規(guī)律。 在保護(hù)層開采與瓦斯抽采中煤層透氣性系數(shù)是關(guān)鍵因素,鉆孔徑向流量法是求取該系數(shù)的最常用的方式,結(jié)合有關(guān)的原理與圖文辨析的方式,詳細(xì)研究了煤層透氣性,時(shí)間以及與流量三者的聯(lián)系,在此基礎(chǔ)上進(jìn)行研究,針對(duì)科研工作和現(xiàn)場(chǎng)管理的實(shí)際情況,提出了求解透氣性系數(shù)的兩種新算法及其計(jì)算流程,并對(duì)時(shí)間準(zhǔn)數(shù)F0與參數(shù)AB函數(shù)關(guān)系中的間斷點(diǎn)問(wèn)題進(jìn)行討論和分析,解決了此區(qū)間內(nèi)求解透氣性系數(shù)相應(yīng)計(jì)算公式等問(wèn)題。 通過(guò)現(xiàn)場(chǎng)實(shí)測(cè)得到下被保護(hù)煤層的卸壓效果、膨脹變形特征與煤層透氣性變化規(guī)律。7a煤層原始瓦斯壓力為1.9MPa,原始瓦斯含量為8.03m3/t；8煤層回采后,7a煤層最大殘余瓦斯壓力為0.3MPa,其最大殘余瓦斯含量為2.64m3/t。當(dāng)保護(hù)層54208工作面推過(guò)鉆孔40m左右的范圍內(nèi),7a煤層的變形量是最大的,為18.2mm；與其對(duì)應(yīng)的最大拉伸變形率為4.8%0,配合的底板巖巷網(wǎng)格式上向穿層抽采鉆孔此時(shí)煤層鉆孔抽采瓦斯純量最大為2.9m3/min。經(jīng)統(tǒng)計(jì)卸壓區(qū)域的7a煤層瓦斯抽采率為75.6%。同時(shí)通過(guò)煤層透氣性系數(shù)的優(yōu)化算法計(jì)算得出卸壓后7a煤透氣性系數(shù)為4.1057m2/MPa·d,較原始透氣性系數(shù)0.0284m2/MPa2·d,擴(kuò)大了216倍。工作面走向方向?qū)Ρ槐Ｗo(hù)層卸壓角為60。；沿傾向方向下卸壓角為75。,上卸邊界為采空區(qū),因此不需要測(cè)試。在8煤的保護(hù)范圍內(nèi),7a煤已經(jīng)消除突出危險(xiǎn)性,為下一步的安全開采奠定了基礎(chǔ)�，F(xiàn)場(chǎng)試驗(yàn)結(jié)果與理論分析和數(shù)值模擬結(jié)果一致。
[Abstract]:Through theoretical analysis, numerical simulation and field test, the stress distribution, expansion deformation characteristics and fracture development of the protected coal seam surrounding rock mass under the mining condition of the upper protective layer are studied. The variation law of coal seam permeability and the optimization algorithm of coal seam permeability coefficient are studied systematically. At the same time, the mechanical model of floor rock layer along coal seam strike is established by analyzing the stress of coal seam floor rock mass. In order to qualitatively and quantitatively analyze the distribution characteristics of the supporting force of the floor, the model is simplified accordingly, the formula of the stress distribution of the floor is deduced, and the stress distribution law of the coal seam floor is summarized. The permeability coefficient of coal seam is the key factor in mining and gas drainage of protective layer, and the radial flow method is the most common way to obtain the coefficient. Combined with the related principle and the method of graph and text analysis, the permeability of coal seam is studied in detail. According to the actual situation of scientific research and field management, two new algorithms to solve the permeability coefficient and their calculation flow are put forward. The discontinuity point problem in the relation between the time datum F0 and the parameter AB function is discussed and analyzed, and the corresponding calculation formula for the permeability coefficient in this interval is solved. Through the field measurement, the pressure relief effect of the protected coal seam is obtained. The characteristics of expansion deformation and the change law of coal seam permeability. The original gas pressure of coal seam is 1.9 MPA and the original gas content is 8.03 m3 / t. The maximum residual gas pressure is 0.3 MPA and the maximum residual gas content is 2.64 m3 / t after mining in 8 coal seam. The deformation of coal seam of 7a is the largest (18.2mm) within the range of 40m or so pushed through the borehole in 54208 working face of protective layer. The corresponding maximum tensile deformation rate is 4.80, and the maximum amount of gas extracted by coal seam boreholes is 2.9 m3 / min. The gas extraction rate of 7a coal seam is 75.6 by statistical pressure relief area. At the same time, through the optimization algorithm of coal seam permeability coefficient, it is found that the coal permeability coefficient is 4.1057m2/MPa d 7 years after unloading, which is 216 times larger than the original gas permeability coefficient 0.0284m2/MPa2 d. The angle of relief of working face strike direction to protected layer is 60. The angle of unloading pressure along the direction of inclination is 75.The upper and unloading boundary is goaf, so it is not necessary to test. Within the protection range of No. 8 coal, 7a coal has eliminated the outburst danger and laid a foundation for safe mining in the next step. The field test results are consistent with the theoretical analysis and numerical simulation results.
【學(xué)位授予單位】：安徽理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TD713;TD322.5

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