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倾斜放煤口上下侧煤岩分界线方程表征及其模拟

Characterization and simulation of the coal-rock boundary equation on the upper and lower sides of the inclined coal caving opening

  • 摘要: 为了探索不同倾角下综放工作面的顶煤放出规律,以唐山矿0291综放工作面为研究背景,采用理论分析、数值模拟及物理相似模拟试验的综合研究方法,推导并获取倾斜放煤口上下侧煤岩分界线表征方程。首先,针对顶煤放出体与煤岩分界线的对应关系,建立了等效于放出椭球体面积的煤岩分界线抛物线方程。然后,采用PFC软件建立煤厚7 m,放煤口宽度为1.5 m,煤层倾角为0°、10°、20°、30°以及40°的数值模型并设置煤岩分界线标记层,获取煤岩分界线的拟合方程。其次,比对理论计算方程,进一步修正煤岩分界线方程。最后,利用自行设计的“三可控”电动放顶煤试验设备进行对应条件的物理相似模拟试验,对修正方程进行合理性检验。依据“见矸关门”原则,进行倾斜煤层单口放煤过程模拟,模拟结果表明:随着煤层倾角增大,煤岩分界线逐渐由对称抛物线分布向非对称抛物线分布转变,其斜下侧煤岩分界线不断远离放煤口中心线,斜上侧煤岩分界线不断靠近放煤口中心线且斜上侧平缓程度远高于斜下侧,理论计算高于模拟结果的等效抛物线特征值,总结了不同倾角下的等效抛物线修正系数,完善了煤岩分界线的理论方程;物理相似模拟试验与数值模拟的相近结果,均体现出倾斜煤层放出体主要来自于放煤口斜上侧的顶煤,放煤口斜下侧的顶煤在放煤过程中则易堆积成拱的分布特征,同时也验证了修正方程的合理性。

     

    Abstract: In order to explore the top coal release law of the fully mechanized top coal caving face under different inclination angles, taking the 0291 fully mechanized caving face of Tangshan Mine as the research background, a comprehensive research approach combining theoretical analysis, numerical simulation, and physical similarity simulation experiments was adopted to derive and obtain the representation equation for the coal-rock boundary line on the upper and lower sides of the inclined coal caving opening. Firstly, the parabolic equation of the coal-rock boundary equivalent to the area of the release ellipsoid is established for the correspondence between the top coal caving and the coal-rock boundary. Secondly, the numerical model of coal seam thickness of 7 m, coal caving opening width of 1.5 m, coal seam inclination angle of 0°, 10°, 20°, 30° and 40° is established by PFC software, and the coal-rock boundary marker layer is set up to obtain the fitting equation of the coal-rock boundary.Furthermore,the theoretically calculated equation is compared to further modify the coal- rock boundary equation. Finally, the self-designed "three controllable" electric top coal caving experimental equipment is used to carry out the physical similarity simulation experiment of the corresponding conditions, and the rationality of the correction equation is tested. According to the principle of "closing the door after seeing the waste", a simulation of the single coal caving opening caving process in inclined coal seams is conducted.The simulation results show that: as the inclination angle of the coal seam increases, the coal-rock boundary gradually transforms from symmetric to asymmetric parabolic distribution, and the lower side of the coal-rock boundary is constantly far away from the centerline of the coal caving opening, and the upper side of the coal-rock boundary is constantly close to the centerline of the coal caving opening, and the upper side of the slope is much more gentle than the lower side of the slope. The theoretical calculation is higher than the equivalent parabolic eigenvalue of the simulation results, and the equivalent parabola correction coefficients under different inclination angles are summarized to improve the theoretical equations of the coal-rock boundary; the similar results of physical similarity simulation experiments and numerical simulation reflect that the released ellipsoid of inclined coal seam mainly comes from the top coal on the upper side of the inclined side of the coal caving opening, and the top coal on the lower side of the inclined side of the coal caving opening is easy to be piled up to form an arch in the process of releasing coal, and the reasonable results of the correction equation are verified at the same time.

     

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