采动影响下煤厚变异区超前支承压力变化规律的数值模拟

Numerical simulation for the changing regularity of the leading support pressure in the coal seam variety region under the mining impact

大量工程实践表明在煤厚变异区及其周围极易出现煤与瓦斯突出和冲击地压等复杂的矿山压力现象。以数值模拟为研究手段,分析了不同煤厚变异区的宽度、煤厚变异程度及采煤工作面分别从厚煤区和薄煤区向煤厚变异区推进的过程,受采煤工作面超前支承压力影响的煤厚变异区及其周围应力分布特征;研究了采动影响下,煤厚变异区及其工作面超前支承压力集中现象和应力分布的规律;揭示了采动影响下煤厚变异区支承压力的转移机制。结果表明:煤厚变异区变薄点比变厚点的原岩应力大,煤厚变化梯度K越大,煤厚变异区应力梯度就越大,应力集中的程度就越高;当工作面接近煤厚变异区时,煤厚变异区对工作面超前支承压力分布特征的影响显著。工作面在厚煤区回采向煤厚变异区推进时,超前支承压力呈"双峰值"分布,而工作面在薄煤区回采向煤厚变异区推进时,超前支承压力呈"单峰值"分布。由于煤岩弹性模量存在差异,工作面回采至煤厚变异区时超前支承压力会向煤厚变薄点转移;相比采煤工作面在厚煤区回采向煤厚变异区推进,从薄煤区向煤厚变异区推进时的工作面超前支承压力集中程度更强烈。

The paper is concerned about the complicated phenomena,such as the coal-gas crash and rock burst that occur from time to time in a variety of coal seam regions and their periphery areas.In this paper,we would like to make an analysis of such phenomena in terms of numerical simulations from the following aspects:the sphere of the coal seam variable region,the degree or extent of the variation and the process of the coal face transfer from some thick-coal areas and some thinner areas in the other variable areas,such as the geological changes in some extracted goafs.In addition,it is also necessary to pay attention to the distribution features of the underground stress in the variable areas and their periphery places under the impact of the dominant abutment pressure from the coal scattering surfaces.Besides,we have also made an exploration of the leading abutment pressure and stress distribution regularity in the variable areas under the impact of the mining activities,which may help us to discover the transfer regularity of the leading abutment pressure in the variable regions.Thus,the results of the afforementioned exploration indicate that the stress of the primary rock in the thinner points tends to be greater than that in the intensive points in the said variable regions.What is more,with the working face getting narrower and narrower to the variable region,the impact of the region on the distribution of the leading abutment pressure may likely be so significant that,when the working face is advancing from thick coal area to the variation area,the advancing abutment pressure may result in a "double peak"distribution.But,in contrast,when the working face is advancing from the thinner coal area to the variation area,the abutment pressure would reveal a "single peak"distribution.Due to the difference of the elastic modulus of the coal seam,the advancing abutment pressure may turn to be a thinning point of the coal seam in case when the advancing mining surface turns back to the stopping points of the variation areas.Thus,as compared with the transfer of the working face to the thick-coal area,the leading abutment pressure may not be so intensive as that when the working face transfers to the thinner coal areas.All of the above findings can be in a position to provide valuable references to the prevention from the dynamic disasters in coal mines and from the catastrophic control over the mining pressure.