浅埋煤层开采地面塌陷裂缝规律及防治方法

Laws and prevention methods of ground cracks in shallow coal seam mining

  • 摘要: 陕北浅埋煤层大规模、高强度开采诱发了严重的地面塌陷,造成大面积土地损毁、水土流失和植被死亡,导致表生环境出现退化。为掌握浅埋煤层开采地面塌陷裂缝发育规律,明晰其机理,提出适宜的治理恢复措施,实现“煤−水−生态”的协调发展,以陕北张家峁井田和柠条塔井田为研究区,采用实地调查、模拟实验和理论分析相结合的方法开展了浅埋煤层开采地面塌陷规律及防治方法研究。结果表明:浅埋煤层开采地表裂缝呈“O”型展布,静态发育特征与采高和地形地貌呈正相关关系、与采深呈负相关关系,且同一工作面切眼附近地表裂缝发育程度最高、巷道次之、面内最低;地表裂缝具有“先开后(半)合”和“只开不合”2种活动特征,整体活动时间为4~9 d,活动期间裂缝初始开裂宽度与最大发育宽度呈线性正相关关系,与稳定宽度呈线性和指数2种正相关关系;黄土沟壑区下坡段开采地表裂缝活动与表土块体的稳定性系数有关,而稳定系数与坡角呈负相关的一次幂函数,与主裂缝间距呈正相关的一次幂函数。上坡段开采坡体裂缝“先开后(半)合”活动受岩块倒转和坡体滑移双重控制,面内沟底裂缝“先开后合”的活动特征受关键岩层运移控制。研究提出了黄土沟壑区沟底贯通型裂缝“裂缝填充+沟道恢复”、坡体裂缝 “裂缝充填+微地形改造”的治理方法和风沙滩地塌陷区的“三圈”修复模式。研究成果在陕北安山煤矿和柠条塔煤矿进行了应用,效果良好。

     

    Abstract: The large-scale and high-intensity mining of shallow coal seams in northern Shaanxi has induced serious ground collapse, resulting in land damage in large area, water and soil loss, and vegetation death, and thus leading to the epigenetic environment degradation. In order to understand the development law of ground collapse and fracture in shallow coal seam mining, clarify its mechanism, and put forward the appropriate treatment and restoration measures to realize the coordinated development of “coal-water-ecology”, Zhangjiamao mine field and Ningtiaota mine field in northern Shaanxi were taken as the study area. On this basis, the development law and control methods of ground collapse in shallow coal seam mining were studied by means of field investigation, simulation experiment and theoretical analysis. As shown in the results, the ground fractures in shallow coal seam mining are distributed in “O” shape, and the static development characteristics are positively correlated with mining height, topography and geomorphology, but negatively correlated with mining depth. Besides, the ground fractures are most developed near the cutting hole of the same working face, followed by the roadway, and least developed in the face. The ground fracture has two characteristics of activity: “opening first and then (half) closing” and “only opening”. The activity lasts 4-9 days in general. During the activity period, the initial fracture width has a linear positive correlation with the maximum development width, and has a linear and exponential positive correlation with the stable width. The ground fracture activity of mining in the downslope section of the loess gully region is related to the stability coefficient of the topsoil block, while the stability coefficient is negatively correlated with the slope toe but positively correlated with the main fracture spacing by a first power function. The activity of “opening first and then (half) closing” of mining slope fractures in the uphill section is controlled by rock block inversion and slope slip, and the activity characteristics of in-plane gulley bottom fractures are controlled by the migration of key rock strata. In this paper, the treatment method of “fracture filling-gulley restoration” was proposed for the penetrating fractures in the bottom of gully and “fracture filling+micro-topography reconstruction” for slope fractures in loess gully region. In addition, the “three-ring” restoration mode was studied for the collapse area in sand beach. The research results have been applied in Anshan Coal Mine and Ningtiaota Coal Mine with good results.

     

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