考虑厚硬岩层的采场覆岩压力拱模型及其应用

    Model of overburden pressure arch in mining areas considering thick-hard rock layer and application

    • 摘要: 采动压力拱模型与厚硬岩层梁结构模型是分析矿山压力与岩层控制的重要空间结构模型,两者相互作用,共同影响开采扰动下覆岩运移和工作面矿压显现特征。基于此,本文结合压力拱理论与厚硬岩层梁结构理论,基于厚硬岩层破断和压力拱发育高度的相互关系,构建了厚硬岩层-压力拱统一理论模型。同时基于厚硬岩层-压力拱模型分析了开采条件和厚硬岩层对覆岩损伤发育和矿压显现的影响。进一步构建了工作面来压预测计算模型,提出了不同影响因素下覆岩损伤发育范围计算方法。研究结果表明:由于厚硬岩层的滞后破断,悬顶上方由于应力集中导致压力拱的非对称式发育现象,其与厚硬岩层的联动破坏导致了强矿压的产生;厚硬岩层初次破断步距随着岩层厚度增加呈线性增长,并且由剪切破坏逐渐转为拉伸破坏;工作面推进速度的增加使得厚硬岩层初次破断步距增长,但当推进速度增长到一定程度后对破断步距的影响将变小;当存在多层厚硬岩层时,随着厚硬岩层层间距的增加,低位厚硬岩层初次破断步距呈非线性减小趋势。采用本文提出的模型对上湾矿12401工作面来压步距进行了理论计算,并与现场实测进行了对比验证,当推进速度较慢时,平均周期来压步距为11.76 m;当推进速度较快时,平均周期来压步距为18.33 m,与现场实测结果基本一致。

       

      Abstract: The mining pressure arch model and the thick-hard rock layer beam structure model are important spatial structural models for analyzing mining pressure and rock layer control. The interaction between these two models affects the movement of overlying rock and the characteristics of mining pressure manifestation in working face under mining disturbance. Based on this, this paper combines the theory of pressure arch and the theory of beam structure in thick-hard rock layers, and constructs a unified theoretical model of thick-hard rock layers-pressure arches based on the relationship between the fracture of thick-hard rock layers and the development height of pressure arches. At the same time, based on the thick-hard rock layers-pressure arch model, the influence of mining conditions and thick-hard rock layers on the development of overlying rock fracture and mining pressure manifestation is analyzed. A prediction calculation model for the weighting of longwall face is further constructed. A calculation method for the development range of overlying rock fracture under different influential factors are obtained. The research results indicate that because of the delayed fracture of thick-hard rock layers and asymmetric development of the pressure arch caused by stress concentration on the hanging roof, their linkage fracture contributes to the occurrence of stronger mining pressure. The initial fracture distance of the thick-hard rock layers linearly increases with the rise of the rock layers’ thickness, and the failure gradually transfers from shear to tensile. The initial fracture distance of the thick-hard rock layers increases with the increase of advancing speed. However, the effect on the fracture distance will shrink after the advancing speed expands to an extent. When there exist multi-strata of thick-hard rock layers, the initial fracture distance of the lower thick-hard rock layers shows a non-linear decreasing trend. Finally, the model proposed in this paper is used to calculate the weighting distance of the 12401-longwall face in Shangwan Coalmine. When the advancing speed is slower, the average period of weighting distance is 11.76 m, and when the advancing speed is faster, the average period of weighting distance is 18.33 m, which is basically consistent with the field measurement results.

       

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