Physical simulation of upper protective coal layer mining with different coal seam inclinations,Energy Science & Engineering

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Physical simulation of upper protective coal layer mining with different coal seam inclinations
Energy Science & Engineering ( IF 3.5 ) Pub Date : 2020-06-09 , DOI: 10.1002/ese3.740
Feng Fang _{1,

2} , Cai Shu ₁ , Hongtu Wang ₁

Affiliation

Protective coal layer (PCL) mining is a preferred regional method for preventing coal and gas outbursts; stress‐relief of PCL mining is the prerequisite of pressure‐relief gas drainage. In order to study the stress‐relief effect of PCL mining on protected coal seams and determine the protection scope of PCL mining under different inclinations, this paper uses physical simulations to study the stress‐relief law and deformation characteristics of the strata during upper PCL mining with a gentle inclination (25°), an intermediate inclination (45°), and a steep inclination (65°). The results show that as the coal seam dip increases, the degree of deformation and failure of the overburden strata gradually decreases, the severe subsidence and expansion area of the overburden strata tends to gradually develop in the uphill direction of the working face, and the floor strata underlying the protective seam significantly expand toward the goaf. However, the absolute value of the upward movement of the floor strata is much smaller than that of the roof strata; and the greater the dip angle, the greater the ratio of floor displacement to roof subsidence. The stress‐relief curve of the protected layer is approximately U‐shaped. As the inclination of the coal seam increases, the stress‐relief range decreases gradually. The maximum relief‐stress and the stress release coefficient of the protected layer initially increase and then decrease. The stress concentration coefficient of the protected coal seam initially increases first and then decreases in both uphill and downhill of the working face in the PCL. As the inclination increases, the stress‐relief angle of the downhill boundary initially increases and then decreases, while the stress‐relief angle of the uphill boundary decreases gradually. Our research results provide guidance for the delimitation of the protected scope of PCLs with different dip angles.

中文翻译：

不同煤层倾角的上保护煤层开采的物理模拟

保护性煤层（PCL）开采是防止煤和瓦斯突出的首选区域方法。PCL开采的卸压是卸压瓦斯抽放的前提。为了研究PCL开采对保护煤层的应力释放效应并确定不同倾角条件下PCL开采的保护范围，本文通过物理模拟研究了上部PCL开采过程中地层的应力释放规律和变形特征。具有缓和的倾斜度（25°），中等的倾斜度（45°）和陡峭的倾斜度（65°）。结果表明，随着煤层倾角的增大，上覆地层的变形程度和破坏程度逐渐减小，上覆地层的严重沉陷和扩张区域倾向于在工作面的上坡方向逐渐发展，保护接缝下面的地层会明显向采空区扩展。但是，地层向上运动的绝对值比屋顶地层小得多。倾斜角越大，地面位移与屋顶沉降的比率越大。受保护层的应力释放曲线约为U形。随着煤层倾角的增加，应力释放范围逐渐减小。受保护层的最大释放应力和应力释放系数先增大然后减小。保护煤层的应力集中系数首先在PCL中的工作面的上坡和下坡首先增加，然后减小。随着倾斜度的增加，下坡边界的应力释放角先增大然后减小，而上坡边界的应力释放角逐渐减小。我们的研究结果为确定不同倾角的PCL受保护范围提供了指导。

更新日期：2020-06-09

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