【作者】 冯国瑞；

【导师】 康立勋；

【作者基本信息】 太原理工大学 ， 岩土工程， 2009， 博士

【摘要】 我国对煤炭需求增长的无限性与资源的有限性这一矛盾日趋突出,而新生替代能源目前还不能取代煤炭的主体能源地位。因此必须节约煤炭资源,提高资源回收率。现有生产矿区(井)中,很多采空区上方遗弃有大面积的可采煤层。科学合理的回收这部分煤层对于建设节约型社会和促进国民经济可持续发展有着十分重要的意义。回收采空区上方遗弃煤层实质上是残采区上行开采。通常煤层开采在顶板岩层中形成的破坏扰动区远大于在底板岩层中形成的破坏扰动区,因此,为减小本煤层开采对临近煤层的扰动,生产实际中几乎全部采用下行开采方式,与此相应人们所开展的理论技术研究也多针对下行开采领域。仅有的上行开采的相关研究,也多集中在以层间距为核心的仅考虑下部煤层开采影响的经验的可行性判定方法、矿压观测分析等方面,而事实上上行开采的核心问题是上、下煤层开采共同影响作用下上部煤层底板的移动变形规律,其移动变形规律又取决于层间岩层结构。因此,进行残采区上行开采层间岩层结构及其上部煤层底板移动变形规律的研究,才能深入奠定残采区上行开采的理论基础,对于进一步促进上行开采技术的发展和高效回收历史弃采煤层,有着重要的理论意义与指导价值。本文从残采区上行开采层间岩层结构及其上部煤层底板移动变形规律入手,通过实验研究、理论分析、数值模拟、现场实测以及工业试验相结合的方法,对残采区上行开采的层间岩层结构、可行性判定理论及方法、上部煤层底板移动变形规律和残采区上行开采矿压控制技术进行了系统的研究。主要研究内容及成果如下:(1)针对残采区上行开采,分垮落法残采区和刀柱式残采区上行开采两种情况,通过相似模拟实验进行了层间岩层结构的演化规律、围岩应力分布规律和层间岩层移动变形规律的研究。研究发现:残采区上行开采层间岩层存在控制层,其中垮落法残采区上行开采层间岩层破断后由于剪胀效应其破断块体之间排列整齐、相互挤压形成块体梁——半拱结构,其半拱部分位于采空区上方四周,为面面接触的块体挤压结构,其轴线(即力的传递作用线)为一曲线;该结构的块体梁部分即采空区上方中部断裂块体相互挤压形成的虽有裂隙却不失整体性的类梁结构。其上方岩层保持较好的完整性和宏观连续性,呈现典型的梁、板结构。就下沉移动量而言,同一岩层中下沉移动量最大的点位于下部采空区中心附近上方,其两侧点位的下沉量随着偏离中心距离的增大而减小。其破断冒落岩层最终形成典型的“变形盆地”,而上方未冒落岩层的下沉曲线会形成局部盆地的波浪状。层间岩层的下位坚硬岩层易成为层间岩层的控制层。对于刀柱式残采区上行开采,煤柱承担上部岩层载荷出现不均衡性——“强柱弱载”和“强载弱柱”,即承载能力弱的煤柱承受岩梁载荷强,而承载能力强的煤柱承受岩梁载荷弱,岩层破断的原因是弱煤柱先压缩变形剪破坏,而强柱端的岩梁产生拉破坏,岩梁断裂垮冒,最终形成冒落带,上方未断裂的岩层基本没有裂隙的产生,保持原完整连续的状态,其作为层间岩层控制层,呈现典型的梁、板结构。(2)在相似模拟实验的基础上,结合岩石力学、块体理论、弹塑性力学和结构力学等理论,分析并获得了下部煤层开采对层间岩层的损伤影响范围,分别建立了垮落法残采区和刀柱式残采区上行开采层间岩层结构的力学模型,并分别进行了详细的力学解析,分析了垮落法残采区上行开采和刀柱式残采区上行开采的机理,同时用数值模拟的方法进行了验证。(3)针对残采区上行开采的层间岩层,通过理论推演的方法研究了上部煤层开采的采动及其扩散影响,分析了垮落法残采区和刀柱式残采区上行开采层间岩层的稳定性,进而基于结构的理论分别提出了垮落法残采区和刀柱式残采区上行开采的可行性定量判定方法,并通过现场试用,对该理论及技术的科学合理性与客观适用性进行了验证。(4)通过现场实测的方法,对残采区上行开采的矿压显现规律进行了研究。结果表明:残采区上行开采由于受下部煤层开采的损伤影响,上部煤层围岩整体性会有不同程度的弱化,在上部煤层开采前已把上覆岩层的自重及其载荷部分传递给采空区范围以外的煤岩体,起到了卸压的作用,残采区上行开采的矿压显现不剧烈,周期来压步距不大。同时,引入概率积分法,对残采区上行开采上部煤层底板移动变形情况进行了预测分析,与现场实测的结果进行了比较分析对照,研究了残采区上行开采上部煤层底板移动变形规律。(5)用数值模拟和理论分析相结合的方法,分析了残采区上行开采上部煤层底板移动变形的力学特性,在此基础上分别建立了垮落法残采区和刀柱式残采区上行开采上煤底板岩层运移的力学模型,通过力学求解,获得了垮落法残采区和刀柱式残采区上行开采上煤底板岩层运移规律的预测模型。(6)在上述理论研究、实验研究与现场实测研究的基础上,形成了残采区上行开采的理论与技术,在山西焦煤西山煤电集团白家庄煤矿进行了试验及工业实施,成功解决了白家庄煤矿8号煤层采空区上方6号煤层回收的技术难题,取得了显著的技术经济效益与环境、社会效益。该技术在理论上是科学的、技术上是可行的。为残采区上行开采提供了理论指导与技术支持。更多还原

【Abstract】 The contradictions have manifested itself between China’s infinite demand of coal and the limited resources gradually , and the coal, as the main energy, new alternative energy sources can not be replaced. It is necessary to save coal resources and improve the recovery rate. There is a large area of workable bed on the top of mined-out region in existing production mining. It is significant for building a conservation-minded society and the promotion of sustainable development of the national economy to recover this coal scientifically and rationally.Recovery of abandoned coal seam on the top of mined-out area is essentially the ascending mining of coal reserve. Coal mining formed the damage zone in the roof strata is usually much larger than in the floor strata. Therefore, in order to reduce the disturbance on mining the close coal seam, mining taken in descending order is adopted almost in practice. Correspondingly, the theoretical and technical studies are carried out mainly for the descending mining. Researches related on ascending mining are concentrated on the coal seam spacing only considered Experiential and Feasibility Test Methods influenced by the lower part of coal mining and mining pressure observation analysis. In fact the core issue of ascending mining is the laws of upper coal floor movement and deformation under influence of upper coal seam mining upon lower coal seam mining depending on the structure between the rock strata. Thus, research on the structure between the rock strata in ascending mining of coal reserve and the laws of upper coal floor movement provide a sound basis for further research in the future and promote the development of ascending mining technology and efficient recovery of the abandoned mining coal seam, which has an important part on the theoretical guidance.In this paper, the research is made from the structure between the rock strata in ascending mining of coal reserve and the laws of upper coal floor movement through a combination of methods such as the experimental research. These are researched systemically, concluding the structure between the rock strata in ascending mining、experiential and feasibility test methods、the laws of upper coal floor movement and deformation and the control system technology of mining pressure residual in ascending mining of coal reserve. The main research content and results are as follows:(1)on account of the ascending mining of coal reserve,separating two ways of caving mining and pillar supporting mining, making a research on the evolution law of the structure between the rock strata, stress distribution of surrounding rocks and the movement and deformation laws between the rock strata. The study found: the control stratum existed between the rock strata in ascending mining. After failure of interlayer in the ascending mining with the method of coal reserve of caving mining , as a result of dilatancy effect ,broken blocks arranged orderly and strained against another formed beams----semi-arch structure, half part of which semi-arch is at the top of mined-out area with extrusion block structure of the surface-to-surface contact which axis (that is, the role of power transmission lines) is a curve ; the structure of block beam is similar with the structure of beam formed by straining against broken blocks of each other in the central of upper mined-out area despite the cracks but not losing the overall structure. The top of rocks maintain the good integrity and macro-continuity and present a typical beam and plate structure. As far as displacement of sinking is concerned, the point with maximum displacement is located above the middle of the lower gob area. The amount of displacement on both sides decreases with the increase of out-of- center distance. The breaking caving rocks forms a typical“deformed basin”, while curve showing the sinking of upper no- carving rocks will form waviness of partial basin. Lower hard ones of interlayer rocks can easily become the control layer of them. As for ascending mining of remaining coal reserve with pillar support, stump undertakes the load from the upper rock leading to a malconformation---------“strong stump with weak carrying capacity“and“weak stump with strong carrying capacity”,namely stump with weak carrying capacity has more capacity of carrying loads from rock beam, and vice versa. This leads to compressive deformation and shear fracture to the weak stump and tensile failure to the rock beam on the edge of the strong stump, which form a caving zone. The rock with no break on the top can maintain the original state of integrity and continuity and form a typical beam and plate structure.(2) Based on analog simulation experiment, with a combination of rock mechanics, block theory, elastic-plastic mechanics and structural mechanics, sphere of influence on the interlayer rock by exploitation of the lower coal seam is analyzed and acquired; mechanical models of interlayer rock structure through ascending mining with caving and pillar supporting are respectively established and analyzed; mechanisms of ascending mining with caving and pillar supporting mining are analyzed and verified by numerical simulation.(3) On account of interlayer of coal reserve in ascending mining, through theoretical deduction ,research on the impact of the upper layer mining and the diffusion, analysis on the stability of interlayer rock in ascending mining with caving mining and pillar supporting mining .Then based on the structural theory, quantitative and feasible determination method is put forward about coal reserve of caving and pillar supporting mining, and through on-site trial , the scientific rationality and the objective application of the theory are proved.(4) Through on-site measurement, regularity of strata behavior by ascending mining of remaining coal reserve is explored. The results indicate that the process of ascending mining is influenced by exploitation of the lower coal seam, which causes the result that integrity of upper coal seal’s wall rock weakens in different degrees. Before exploitation of the upper coal seam, self weight and load of overlying rock have been passed on to the rock mass outside the gob area functioning as pressure relief. Strata behavior by ascending mining of remaining coal reserve is not dramatic and periodic weighting length is short.Meanwhile, with the method of probability-integral, mobilization and deformation conditions of coal floor by ascending mining of remaining coal reserve is predicted and analyzed; comparision and contrast between the results from analysis and those from on-site measurement have been made; regularity of coal floor’s mobilization and deformation by ascending mining of remaining coal reserve is explored.(5) Using combination with numerical simulation and theoretical analysis methods, analysis of the mechanical properties of the upper coal seam floor movement and deformation in ascending mining of coal reserve. On the basis, building the mechanical model of upper bottom plate rock layer migration in ascending mining concluding caving and pillar supporting mining. Through the mechanical solution method to obtain the forecast model.(6)Based theory, laboratory research and field measured studies, forming theory and technology of ascending mining in coal,carrying out tests and industrial implementation in the company of coal-fired electricity in Shanxi Coking Coal Xishan Coal Mine Group Baijiazhuang,sovling the technical problems about goaf recovery of the 6th coal seam under the 8th coal seam, achieved significant economic and environmental, social benefits. The technology in theory is a scientific and technically feasible. Residues up to the exploitation of mining area to the paper provide a theoretical guidance and technical support for ascending mining in coal reserve.更多还原