【作者】 蒋威杰；

【导师】 邹声华；

【作者基本信息】 湖南科技大学 ， 安全技术及工程， 2011， 硕士

【摘要】 煤与瓦斯突出是煤矿最为严重的灾害之一,而保护层开采是防治煤与瓦斯突出的有效措施。本文结合了弹塑性力学、岩体力学、渗流力学等相关理论,以土朱矿上保护层开采为工程背景,分析了上保护层开采后,底板岩层的应力分布、移动变形、被保护层渗透率分布,在此基础上研究了上保护层开采的保护范围及瓦斯运移规律。在前人的基础上,运用弹塑性力学,建立采场底板力学模型,分析得出了采场底板应力变化、位移变化规律及被保护层渗透率分布规律。(1)在远离采空区的地方不受采动影响为原始应力区;在采空区两端煤柱上,产生了应力的集中为应力集中区;在采空区下方一定范围内,应力是降低的为应力降低区,并随着工作面的推进采空区后方应力逐渐恢复。随着层间距的增加,采动对底板的影响不断减少。(2)分析了采场底板岩层位移变化情况,在应力集中区岩层下沉,在应力降低区岩层发生底鼓现象,在采空区底板下方被保护层处最大位移量超过100mm,并且位移量随着层间距的增加而减少。(3)对土朱煤矿保护范围进行了分析,并拟合了上保护层开采保护范围曲线,指出土朱矿3煤开采后,沿走向方向卸压角在39.4°~69.8°之间,倾斜方向卸压角为75.43°左右。(4)通过应力与渗透率的关系得出了保护层开采后土朱矿5煤层渗透率的分布规律,并分析了瓦斯流动通道。分别利用FLAC3D软件、COMSOL软件对土朱矿保护层开采过程中围岩应力、位移的变化规律及被保护层瓦斯运移规律进行了数值模拟。(1)模拟了土朱矿上保护层开采过程中底板应力变化及位移变化规律,并根据底板应力的分布划定了保护范围,在走向方向上卸压角为52.36°~61.89°;在倾斜下方为73.2°,倾斜上方为74°。(2)模拟土朱矿上保护层开采过程中,被保护层瓦斯运移规律。开采20m后,被保护层最低瓦斯压力降低到了1.125MPa;开采40m时,被保护层最低瓦斯压力降低为0.65MPa;开挖60m后,被保护层最低瓦斯压力降低到了0.5MPa。针对土朱煤矿的实际情况,设计了土朱矿上保护层开采的观测方案,分析了保护层—3煤开采过程中,被保护层应力及瓦斯压力的变化规律,并划定了保护范围,沿走向卸压角为53.7°~65°,沿倾斜卸压角为74.9°左右。这与理论分析及数值模拟对比:是吻合的。从而为今后运用理论分析、数值方法预测突出矿井保护层开采效果奠定了基础。更多还原

【Abstract】 Coal and gas outburst is one of the worst disasters in coal mine, the implementation of protective mining is effective measures to prevent coal and gas outburst in coal mine with condition. Combined with the elastic-plastic mechanics, rock mechanics, fluid dynamics and related theories, taking the TuZhu upper protective layer’s mining as the engineering background, this paper analyzes the stress distribution of the floor strata, movement and deformation and the protected layer’s permeability distribution after the upper protective layer’s mining, on the basis of which the scope of protection and the gas migration law of the upper protective layer’s mining is studied.based on the former,the paper used elastic-plastic mechanics to establish the mechanical model of stope floor and obtained the stress variation,displacement change and protectived layer permeability distribution of stope floor.(1) the place far from goaf where is primitive stress area does not suffer from Mining influence; both ends coal pillar of goaf where is stress concentrated area the stress produced concentration; in a certain range under goaf where is stress decreasing area, the stress is lower, and with work face advancing, the area behind of goaf stress recover gradually. Along with the increase of the lamellar spacing, the influence of mining to floor is dwindled.(2) Analyzed the displacement change of stope floor rock.in the stress concentrated area,the stope floor rock is sinking;in the stress decreasing area, the stope floor rock is heave. The maximal displacement of protected layer under the goaf More than 100mm and Along with the increase of the lamellar spacing the displacement is decreasing.(3) Analyzed the scope of protection of Tu-zhu mine and obtained the fitting curve of the scope of upper protective layer, pointed out that after the exploitation of Tu-zhu coal seam 3, released angle along the strike direction ranged from 39.4°~ 69.8°, the sloping direction was 75.43°or so. (4) Obtained the distribution of permeability in Tu-zhu coal seam 5 through the relationship between stress and permeability, and analyzed the gas flow channel.FLAC3D software and COMSOL software were used to simulate the surrounding rock stress and displacement variation and gas migration during the protection layer mining of Tu-zhu mine.(1) Simulate the displacement variation of stress and stress distribution under the floor when mining the upper protective layers. based on the displacement variation of stress and stress distribution under the floor, delineated the released angle, in the direction of trend, the released angle range from 52.36°~61.89°; in the sloping direction, the released angle of lower is 73.2°, the released angle of top is 74°(2) Simulate the Tu-zhu mine upper protective layer of during the mining, and gas migration law in protective layer. Exploitation of 20m, the minimum gas pressure in protective layer was reduced to 1.125MPa; exploitation of 40m, the minimum gas pressure in protective layer was reduced to 0.65MPa; excavation of 60m, the minimum gas pressure in protective layer was reduced to 0.5MPa.According to the actual situation of TuZhu coal mine, the paper designs the observation program of the TuZhu upper protective layer’s mining, analyzes the protective layer, the protected layer’s stress and change law of the gas pressure in the process of 3 coal mining, and designates the protection range that along the alignment the relief angle is 53.7°~ 65°and along the slope the relief angle is 74.9°around. With the comparison of the theoretical analysis and the numerical simulation, it is shown that the results are consistent. this laid a foundation for using methods of theoretical and numerical to predict protective effect of coal and gas outburst mines in the future.更多还原