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为了解厚度效应对复合煤岩体的影响,考虑了瓦斯及顶底部砂岩的作用,通过改变原煤与顶底部砂岩的厚度配比,运用含瓦斯煤热流固耦合三轴伺服渗流试验装置,研究了厚度效应对复合煤岩体的力学特性及破坏形式的影响。结果表明,复合煤岩体的三轴应力应变曲线与全煤样有很好的一致性,其三轴抗压强度较原煤有一定程度的增强;顶部砂岩与原煤厚度比落入1.00~1.20极值区间的复合煤岩体,易出现三轴抗压强度极值,且远离极值厚度比的三轴抗压强度均有不同程度下降;当厚度比接近1.00时,易出现峰值体积应变。当体积应变接近时,厚度比落入极值区间内的煤岩体强度较大。复合煤岩体的破坏以单斜面剪切破坏为主,且大部分为非完全破坏;中部原煤会产生多种形式的破坏,厚度比落入极值区间内的复合煤岩体,其煤体破坏以单斜面裂隙或垂直裂隙形式破坏,且三轴抗压强度要高于其他裂隙形式破坏。
In order to understand the influence of thickness effect on the complex coal and rock mass, considering the role of gas and top and bottom sandstone, by changing the thickness ratio of raw coal to top and bottom sandstone, using the three-axis servo- Effect of thickness effect on mechanical properties and failure mode of composite coal and rock mass. The results show that the triaxial stress-strain curve of the composite coal and rock mass is in good agreement with the whole coal sample, and the triaxial compression strength is enhanced to a certain extent compared with that of the raw coal. The thickness ratio of the top sandstone to the coal falls into the range of 1.00-1.20 The complex coal and rock mass in the interval is prone to the extreme value of triaxial compressive strength, and the triaxial compressive strength away from the extreme thickness ratio decreases to different extents. When the thickness ratio is close to 1.00, the peak volumetric strain appears easily. When the volumetric strain is close, the thickness ratio of coal and rock mass falling into the extreme value interval is greater. The failure of the composite coal and rock mass is dominated by shear failure of the monocline, and most of it is not completely destroyed. The middle coal has various forms of damage, and the thickness ratio of the composite coal and rock mass falling into the extreme value interval, The failure is destroyed by single-slope cracks or vertical cracks, and the triaxial compression strength is higher than that of other cracks.