不同变异系数煤层应力场与瓦斯场规律的数值模拟研究

Numerical simulation and influence analysis of coal seam outburst risk with different coefficient of variation

为揭示煤层厚度变化对煤层突出危险性的影响,建立了煤层变形场和瓦斯场耦合模型,并基于高斯分布建立了不同煤层变异系数的煤层模型,揭示了不同变异系数下的煤层应力场和瓦斯场分布规律。结果表明:稳定煤层与非稳定煤层应力场差别显著,非稳定煤层在煤层较薄处产生了应力集中现象,向厚煤层区域掘进时呈线性减小;煤层较厚处稳定煤层的应力大于非稳定煤层,且随着煤层变异系数的增加进一步减小;不同变异系数煤层随着变异系数的增加应力逐渐增加,主应力的增长速率随着掘进距离的增加逐渐增加;煤层厚度变化导致了煤层受到顶板的水平应力作用,在煤层较薄处,顶板水平应力指向煤层,导致煤层较薄处产生了应力集中,在煤层较厚处,顶板水平应力背离煤层,导致煤层应力相比较薄处小,且瓦斯浓度大、渗透率小、构造煤发育较多,在扰动下容易发生突出。

To reveal the influence of coal seam thickness variation on the outburst danger of coal seam,a coupled model of coal seam deformation field and gas field was established,and coal seam models with different coal seam variation coefficients were established based on Gaussian distribution.The distribution laws of stress field and gas field under different variation coefficients were studied.The main research conclusions are as follows:there is a significant difference in stress field between stable coal seams and unstable coal seams.The unstable coal seams form stress concentration phenomenon at thin coal seams,which decrease linearly when excavating towards thick coal seam areas.The stress of stable coal seams is greater than that of unstable coal seams at the thick coal seam,and the stress decreases further with the increase of coal seam variation coefficient.The stress of coal seams with different variation coefficients gradually increases with the increase of variation coefficient,and the growth rate of the principal stress increases with the decrease of advancing distance.The thickness variation of coal seam leads to the lateral force of the roof acting on the coal seam.For the thin coal seam,the lateral force of the roof is directed towards the coal seam,which leads to stress concentration at the thin coal seam.For the thick coal seam,the lateral force of the roof deviates from the coal seam,resulting in smaller stress than that of the thin coal seam.In addition,with high gas concentration,low permeability,and more developed structural coal,it is prone to outburst under disturbance.