【作者】 史红；

【导师】 姜福兴； 谭云亮； 杨永杰； 马其华；

【作者基本信息】 山东科技大学 ， 采矿工程， 2005， 博士

【摘要】 综采放顶煤技术经过近二十多年的迅速发展,无论是在理论研究还是工程技术方面,已经达到了很高的水平,但仍然存在很多问题尚未解决。针对综放采场顶板运动稳定性的特点,论文重点解决初次来压阶段综放采场厚层坚硬顶板的运动规律及其“关键性”问题,以及初次来压阶段和正常推进阶段顶煤放出率的变化对厚层坚硬顶板结构稳定性的影响。结合工程实际,应用论文研究成果,对河南义马常村矿巨厚砾岩孤岛综放面顶板结构的稳定性、综放工作面“异常压力”的产生机理进行研究。 在初次来压阶段,采用两端嵌固梁考虑体积力的力学模型,利用弹性理论分析了厚层坚硬岩层的应力分布。厚层坚硬岩层的运动方式分别为:沿中间弱面被剪开的分层运动;全厚度压剪破坏;弯拉破坏。通过力学分析,得到了上述三种运动方式的力学判据和判断曲线。得出了厚层坚硬岩层分层运动后,对其他岩层的控制作用减弱,其“关键性”下降的结论。现场实例检验表明,此方法用于老顶初次断裂方式和步距的预测,比传统的简单加线载荷、用材料力学进行分析的方法更符合厚层坚硬顶板的实际情况,能对“关键层”在运动过程中的破断方式做出准确的判断。 针对综放采场顶板结构的运动特点,提出了老顶运动失稳的两种形式,分别为:由 于顶煤放出率增加,顶板结构下沉量过大而造成的在运动过程中整体变形失稳;由于工 作面推进跨度增大或上覆岩层存在断层等构造,而造成的局部铰接失稳。建立了初次来 压和周期来压阶段顶板稳定性分析的结构力学模型,利用最小势能原理分析了老顶结构 在初次来压和周期来压阶段保持整体变形稳定的条件;利用强度理论分析了老顶结构在 初次来压和周期来压阶段保持局部铰接稳定的条件。得到了顶板结构保持整体变形稳定 和局部铰接稳定相统一的、与顶煤放出率相关的力学判断准则。 根据综放采场顶板结构运动特点,详细描述了综放采场上覆岩层中需控岩层的范围。 分析了组成老顶结构的可能岩块数。得到了初次来压和周期来压阶段不同岩性的顶板由 岩层厚度表示的稳定性判断曲线,给出了基于顶煤放出率和关键岩层厚度的岩层运动稳 定性判断方法。 结合具体采场实例,验证了通过调整顶煤的放出率、利用力学原理预测运动岩层范 围和稳定性,从而实现厚层坚硬顶板工作面的安全开采的可行性。更多还原

【Abstract】 The theory research and the engineering technology of fully-mechanized sublevel caving face have achieved through many year’ s development. But there are a lot of problems which are not solved. Aimed at the stability characteristic of fully-mechanized sublevel caving face, the key problems which this paper will solve are as follows: the first one is the movement rule and key role of hard and massive overlying strata of fully-mechanized sublevel caving face at first weight period; the second one is the relationship between the top coal’ s recovery ratio and the stability of roof structure of fully-mechanized sublevel caving face at cyclic weight period. Using the research conclusions mentioned above and the engineering data, the stability of the isolated fully-mechanized sublevel caving face under weighty conglomerate rock of Changcun Coal Mine in Henan province and the mechanism of "Abnormal Pressure" of fully mechanized sublevel caving face are studied.Based on the mechanics model of considering the gravity of fixed beam as the centralizing force, there are three kinds of movement mode of hard and massive overlying strata at the first weight period, namely, the shearing with and without the weak interbedding to directly cause the key falling of strata; rupture resulting from pressure and shearing in the whole strata; and rupture of the strata close to two ends of beam. This paper presents the mechanics judgment modes of the possible movement of the hard and massive strata by analyzing the breaking patterns of the hard roof of the overlying strata of longwall face using the elasticity theory. In this paper, the structure of the main roof before its initial fracture is viewed as the fixed beam model, and the gravity of the hard roof and its overlying soft strata is considered as the distribution force which acts on the fixed beam. By use of the elastic theory and analyzing the stress field of the fixed beam under the influence of the gravity, the author suggests the mechanics judgment model of the overlying strata in three kinds of possiblemovement. The conclusions are that the key role of hard and massive overlying strata after their shearing. According to our study, the analysis of the breaking patterns of the roof of the hard and massive strata based on the consideration of its gravity, compared with the simple uniform stress way which is usually used, is more likely to show the true situation of the strata and the accurate breaking pattern of the key layer in its movement. This can help provide the theoretical basis for controlling the hard and massive strata in mining engineering. Field experiments have also shown clearly that this method is useful for the prediction of the initial breaking and step of the main roof of the hard and massive strata.Based on the roof movement characteristic of fully-mechanized sublevel caving face, two kinds of losing stability mode of roof are brought forward, Namely, the losing stability of the whole deformation of roof structure because of the increasing of the top coal’ s recovery ratio; the losing stability of part contact of the main roof because of the increasing of roof span and some fabrics such as faultage in overlying strata. The mechanics models analyzing roof stability at first weight and cyclic weighting period are established. Based on the structure stability theory and the strength theory, two kinds of limited convergence maintaining the stability of the whole deformation of roof structure and the stability of part contact of the main roof are gained. According to the comparison of the two limited subsidence and the subsidence of roof brought about by the movement situation of roof in the course of rotation, the unifying mechanics conditions between the stability of the whole transmutation of roof structure and the stability of part contact of the main roof are analyzed and the judgment rules of roof stability with the top coal’ s recovery ratio are established.Based on the movement characteristic of roof structure in fully-mechanized sublevel caving face, the range of movement strata of overlying strata is described particularly, and the possible numbers of rock block composing roof structure are analyzed. The stability judgment curves being relative to strata thickness at first weight and cyclic weighting period are gained. The movementstability judgment methods of key strata are presented according to the thickness of key strata and the top coal’ s recovery ratio. The conclusions are that the thickness of key strata is the main factor influencing the stability of the whole transmutation of roof structure, the intensity and thickness of key strata, the friction characteristic of the interface between two blocks rock are the main factors influencing the stability of part contact of the main roof. Based on an example of fully-mechanized sublevel caving face, the feasibility of the methods forecasting the range of movement strata and the stability of roof structure according to adjusting the top coal’ s recovery ratio and using mechanics theory is tested.Aimed at phenomena of support’ s being pressed to burst or be unable to work in a few fully mechanized sublevel caving longwall faces and based on analyzing the factors of geology, mining, mechanics and so on, the mechanism of "Abnormal Pressure" of fully mechanized sublevel caving face is discussed.更多还原