晋北黄土沟壑区综放开采覆岩破坏规律研究

    Study on failure law of overlying rock in fully mechanized caving mining in loess gully area in northern Shanxi

    • 摘要: 针对晋北黄土沟壑区煤层埋深浅、厚土层、薄基岩以及综放开采强扰动的问题,综合数值计算与现场实测2种方法探究采动覆岩破坏特征。模拟结果得出:强开采扰动条件下,采动破坏性影响将逐深向浅次第传递,随着工作面回采距离增加,采动岩层位移变形具有累积效应,采动破坏性影响存在纵向快速发展—纵向停滞横向扩展—纵向快速突破的发展过程,裂采比约为19.7。现场实测得到:10108工作面采动破坏性影响已突破基岩与土层的临界面,采动裂缝上下贯通,采空区上覆岩层已不具备阻隔水性能,采动覆岩破坏特征以高角度纵向裂隙为主,采动覆岩破坏高度将不小于198.2 m,裂采比将不小于22。综合研究结果表明:厚煤层综放开采造成上覆岩层破坏程度更加剧烈,导水断裂带较为发育,塑性强的黏性红土虽对采动裂隙的纵向发育具有抑制效应,但在工作面回采后一定时期无法自然弥合而丧失阻隔浅部松散层水和地表水,实测裂采比较之数值模拟结果与经验公式分别相差10.5%和9.5%,水体下采煤应及时制定合理的防治水技术措施。

       

      Abstract: Aiming at the engineering background of shallow coal seam burial depth, thick soil layer, thin bedrock and strong disturbance of fully mechanized caving mining in the loess gully area of northern Shanxi Province, two methods of comprehensive numerical calculation and field measurement are used to explore the failure characteristics of overlying rock during mining. The simulation results show that: under the condition of strong mining disturbance, the destructive influence of mining will be transmitted from depth to shallow. With the increase of the mining distance of the working face, the displacement and deformation of the mining stratum has a cumulative effect, and the destructive effect of mining has a development process of vertical rapid development, vertical stagnation and horizontal expansion, vertical rapid breakthrough, and the ratio of the water-conducting fracture zone to the mining thickness is about 19.7; the field measurement shows that the destructive impact of mining on the 10108 working face has broken through the critical plane between the bedrock and the soil layer, the mining cracks are connected up and down, and the overlying rock layer in the goaf no longer has the ability to block water. The failure characteristics of mining overburden are mainly high-angle longitudinal fractures. The damage height of mining overburden will not be less than 198.2 m, and the ratio of the water-conducting fracture zone to the mining thickness will not be less than 22. The comprehensive research results show that: fully mechanized caving mining of thick coal seam results in more severe damage of overlying strata, and high angle of mining-induced overlying strata can lead to the development of water fractures. Although the viscous laterite with strong plastic has a restraining effect on the longitudinal development of mining-induced fractures, it cannot naturally bridge and lose the barrier of shallow unconsolidated strata and surface water in a certain period after mining at the working face. The ratio of the water-conducting fracture zone to the mining thickness is 10.5% and 9.5% different from the numerical simulation results and the empirical formula respectively. Therefore, reasonable water prevention and control measures should be formulated in time.

       

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