【作者】 范晓刚；

【导师】 王宏图；

【作者基本信息】 重庆大学 ， 采矿工程， 2010， 博士

【摘要】 随着煤矿开采深度的不断增加,煤与瓦斯突出日益成为制约矿井安全高效生产的主要因素,而开采保护层是最有效的区域性防突措施。保护层开采时一个重要的问题就是保护范围的划定,然而我国西南地区大多数煤层都是严重突出的急倾斜煤层,采煤方法比较特殊,按照传统的方法(即参考《防治煤与瓦斯突出规定》)划定其保护范围,在实际应用中出现偏差。因此,本文以南桐矿业公司东林煤矿的急倾斜俯伪斜下保护层开采为研究的工程背景,采用实验室试验、理论计算、数值模拟和现场工业试验等相结合的方法,研究了急倾斜俯伪斜下保护层开采后被保护层的有效保护范围及其影响因素。本文的主要研究成果和结论有:①通过在煤矿现场取样,在实验室进行了煤岩层的抗压、抗拉和抗剪试验,获得了保护层周围煤岩体的各种物理力学特性参数。②基于煤层卸压的应力保护准则和变形卸压准则,建立了俯伪斜下保护层开采的有限元三维数值模型,对俯伪斜下保护层开采后覆岩的移动变形和卸压程度进行了数值模拟分析研究,并对被保护层的有效保护范围进行了分析和计算,确定了被保护层的有效保护范围。结果表明:保护层开采在倾斜方向的上部和下部卸压角分别为90°和80°,沿走向方向的卸压角在倾斜上、中、下部呈不均匀分布,其大小为44°~68°,安全起见按44°划定走向方向的卸压保护角。③通过开展东林煤矿俯伪斜下保护层开采的现场试验,确定了研究区域内下保护层开采保护范围的现场实测结果。试验结果表明:采用马丽散固化剂结合水泥石膏浆机械封孔的方法能更好的密闭钻孔,使瓦斯压力参数的测定更加准确;保护层开采的倾向下部卸压角为83°,走向卸压角为45°,保护层工作面超前被保护层掘进工作面的最小距离为53 m。数值模拟计算和现场考察的结果比较接近,本文采用的数值模拟方法划定俯伪斜下保护层开采的保护范围是可行的。④针对急倾斜煤层开采后冒落矸石在采空区沿倾斜方向的不均匀充填,在倾斜上部无充填,中部充填较弱,下部充填较为密实的情况。本文对充填体产生的支撑载荷进行了分析,建立了充填体对顶板的支撑载荷函数。⑤根据弹性薄板理论,建立了基于采空区不均匀充填的俯伪斜下保护层开采后基本顶的移动变形和破坏的力学模型,推导出了俯伪斜基本顶的挠曲函数,并根据Marcus修正解计算和分析了基本顶初次破断的极限跨距;在此基础上提出了俯伪斜下保护层开采基本顶初次来压时的顶板管理方法。⑥基于关键层理论,采用理论计算分析和数值模拟的方法确定了急倾斜下保护层开采后上覆岩层中的关键层,并计算了关键层的初次破断距;结合现场的观测,分析了关键层的破断对覆岩移动变形、岩层中离层和裂隙的分布、被保护层瓦斯涌出及保护范围的影响。更多还原

【Abstract】 With the increasing of exploitation depth for coal mine, coal and gas outburst became the major factor of restricting the safe and effective exploitation to a mine, while mining the protective layer as the most effective measure of preventing the coaland gas outburst in the regional in the world was widely used in a serious outburst coal mine. The determination of protecting scope was an important problem when exploiting the protecting layer, which closely associated with many factors such as the existent condition, the mechanical properties of surrounding rock, mining method and roof management method.In the Southwest, the majority coal seam was steep incline and serious coal and gas outburst, and the geological structure was complicated. Furthermore, informal mining methods were adopt. Consequently, the determination of protection scope was much more difficult. According to the traditional method, which referred to the regulation of preventing coal and gas outburst, the protection scope was different from the real protection scope. So it’s essential to determinate the protection scope for mining the steep incline under-protection layer renewedly.Taking the exploitation of steep incline under-protection layer of Donglin coal mine in Nantong Mine company as researching project background, combining with the test in laboratory, theoretical arithmetic, numerical simulation and industrial tests, the motion and breaking regulation of cover mass and the protection scope of protected layer after exploitation the under-protection layer was studyed by this paper. The sesults of this paper could be concluded that:①The basic physical-mechanics parameters of coal and rock arround the protection layer at investigation area were confirmed by the mine-site sampling, processed into standard test pieces, the compression test, the tensile test and the shear test.②A three-dimensional finite element numerical simulation model to simulate the exploition of oblique under-protection layer was established. The distortion and pressure-relieving degree of overlying rock srtatum was anslyzed and researched by numerical simulation after the exploition of oblique under-protection layer, and the effective protection scope of protected layer was analyzed and calculated on the basic of the stress protection regulation and the distortion protection regulation for pressure-relieving of protected coal seam. The result indicated that the upside and downside pressure-relieving protection angles along the incline were 90°and 80°respectively when exploiting the under-protection layer. The pressure-relieving protection angle along the strike distributed unevently on the upside and middleside and downside along the incline, and valued from 44°to 68°. For the reasons of security, it was reasonable to determinate the pressure-relieving protection angle along the strike by 44°.③Through the field industrial examination for the exploition of steep oblique under-protection layer in Donglin coal mine, the field test result of protection scope of the exploition of under-protection layer in the investigation region was obtained. The result of examination showed that: the investigation drill could be sealed by use of the method of Malisan curing agent combining with the concrete and plaster slurry mechanism sealling, and the test results of kinetic parameter for gas were more exact. The pressure-relieving protection angle of downside on the incline after the exploition of the under-protection layer was 83°, and the pressure-relieving protection angle along strike was 45°. The minimal leading distance between the coal face of protection layer and advancement face was 53 m. The result of numerical simulation calculation was near the result by field investigation and leaned toward the security directon. Consequently, ascertaining the protection scope of the exploition of steep incline oblique under-protection layer by use of numerical simulation was feasible.④The caving recrement filled the gob unevently along the incline after the exploitation of steep incline coal seam. There was no filling in the up-incline, weak in the middle-incline, and dense in the under-incline. The support load from filling recrement was analyzed and studyed, and the function of support load to the roof was established.⑤Based on the elastic thin plate theory and the unevently filling of gob, the mechanics model of distortion and breaking for basic roof after the exploitation of under-protection layer. The deflection function of basic roof was deduced, and the terminal span for the first breaking of basic roof was analyzed and calculated on the basis of Marcus modify solution. Roof control method of the exploition of oblique under-protection layer when the first weighting of the basic was analyzed and calculated.⑥According to the Key Strata Theory, the key strata of roof stratum was determinated after the exploition of steep incline under-protection layer, and it’s first breaking interval was analyzed. Combining with the field test, the impact of the key strata’s breaking to the distortion of overlying rock srtatum and the distributing of absciss layer and cranny and the gas effusing from protected layer and it’s protection scpoe was analyzed.更多还原