岩层控制的全柱状学术思想与实践

Thought of full-stratigraphy and its practice in ground control

  • 摘要: 岩层控制是通过控制采动岩层破断运动来减轻或消除采动损害的一门科学,目的是为了保障煤炭安全、高效、绿色开采。传统岩层控制研究思想与方法存在2方面局限:对覆岩进行均化而不能抓住主要矛盾,仅关注局部岩层运动而缺乏对全地层覆岩运动的研究。针对这些问题,在关键层理论应用研究过程中,形成了岩层控制的“全柱状”学术思想,其内涵包括2方面:一是 “抓主要矛盾”,找到对岩层运动起主要控制作用的关键层(即主要矛盾),避免对覆岩均化处理。二是“关注全局”,将采动覆岩作为整体研究,充分考虑关键层所处的复杂地层场景条件可能对关键层破断的影响,从整个岩层移动角度研究矿压显现、水与瓦斯运移、开采沉陷等。按照全柱状学术思想研究岩层控制时,首先需要获取研究区域内不同开采尺度(矿井、采区、工作面及块段)地层的钻孔 “全柱状”,即包含从开采煤层直到地表所有岩层信息的全取心完整柱状,根据研究区域内多个钻孔柱状的关键层判别,形成研究区域内岩层赋存特征的整体画像,避免仅采用局部柱状或综合柱状,也不能对全柱状进行均化处理。充分考虑原岩应力、地质构造、地形地貌、水体载荷、开采部署等多种具体场景因素可能导致的关键层受载差异与破断异常,以及不同区域柱状关键层位置的变化可能对岩层运动产生的影响。在此基础上,建立关键层运动与各种采动损害的联系,据此分析问题发生机理并提出针对性的岩层控制方法。全柱状学术思想推进了岩层控制理论发展与实践创新,解决了压架、突水、沉陷等灾害防控的系列工程难题,取得了显著成效。利用全柱状学术思想取得的岩层控制理论创新主要包括:揭示了采动覆岩卸荷膨胀累积效应,建立了采动覆岩“关键层−松散层拱”结构模型,提出了基于关键层位置的导水裂隙带高度预计方法,建立了基于关键层结构的地表沉陷预计方法,为工程应用奠定了基础。全柱状学术思想在工程应用方面的典型实例包括:找出了浅埋煤层沟谷上坡段、松散承压含水层下等特定条件下开采压架的根本原因,彻底解决了压架防治工程难题;量化关键层位置对“导高”的影响,解决了顶板异常突水防治难题;提出了煤层群卸压瓦斯的“三带”分布,指导了卸压瓦斯抽采实践;研发了覆岩隔离注浆充填技术,创建了地面钻孔一注式高效充填绿色开采新模式,解决了地表沉陷控制等难题,已得到全面推广应用。

     

    Abstract: Ground control is a science of mitigating or eliminating mining damage by controlling the breaking motion of mining rock strata, with the aim of ensuring safe, efficient and green mining. There are two limitations in the traditional thoughts and methods of ground control research: only studying the local rock movement instead of the overall movement of the overlying rocks in the whole stratum, and homogenizing the overlying rocks instead of grasping the main contradictions. In view of these problems, in the process of key stratum theory research and engineering application, the ‘full-stratigraphy’ thought of ground control has been formed, whose basic connotation is as follows: firstly, ‘grasping the main contradiction’, to find the key stratum (i.e. the main contradiction) that plays a major role in controlling the overburden movement without homogenizing the overlying rocks. Secondly, it is ‘overall view’, which takes the overburden as a global object, considers all the factors that may have a significant impact on the breakage and instability of the key stratum from a global view, and analyses the manifestation of mining pressure, water and gas transport, and surface subsidence from the point of view of the whole activity of the overburden movement. According to the basic connotation of the thought of full-stratigraphy, when carrying out ground control research, it is necessary to collect full-stratigraphy data and key stratum discrimination studies within different mining scales (mine, mining area, workings and blocks), the complete coring columnar that contains all the information of the rock strata from the vicinity under the mined coal seam all the way to the surface, and then form an overall portrait of the rock stratum endowment characteristics in the research area through the comparison of the columnar of multiple drill holes. The comparison of multiple drill hole columns will form an overall picture of the characteristics of the rock strata in the study area, rather than using only partial columns or comprehensive columns, or homogenizing the whole column. It is necessary to consider the possible effects of changes in the location of the columns and key stratum in different regions on the movement of the rock layer. Secondly, it is also necessary to fully consider the original rock stress, geological structure, topography, water load, mining deployment and so on, which may lead to abnormal loads on the key stratum and its breakage. On this basis, the relation between key stratum movement and various mining engineering phenomena or disasters is established, based on which the mechanism of the problem is analyzed and the targeted rock control methods are put forward. The full-stratigraphy thought has promoted the theoretical development and practical innovation of ground control, solved a series of engineering problems of disaster prevention and control such as supports crushing, water-inrush, subsidence, etc., and achieved remarkable results. The main innovations in the theory of rock stratum control achieved by using the full-stratigraphy thought include revealing the accumulative effect of overburden strata expansion induced by stress relief, establishing a structural model of ‘key stratum - loose stratum arch’ of the mining overburden, proposing a new method to predict the height of fractured water-conducting zone by location of key stratum, and initially establishing a method for estimating the surface subsidence based on the structure of key stratum, and so on. It lays a foundation for engineering application. Typical examples of the full-stratigraphy thought in engineering application include: finding out the root cause of pressurized racking in the uphill section of shallow buried coal seam gully and mining under unconsolidated confined aquifer, completely solving the engineering problems of pressurized racking prevention and control; quantifying the influence of the location of the key stratum on the ‘water flowing fracture height’, solving the problems of preventing and controlling the abnormal water breakout of the roof; proposing the ‘three-zone’ distribution of the unloaded gas in coal seam, which has guided the practice of unloaded gas extraction; it has developed isolated overburden grout injection and filling technology, and created a new mode of ground drilling and one-injection high-efficiency filling and green mining, which has solved the problems of surface subsidence control, and has been comprehensively popularized and applied.

     

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