厚硬顶板特厚煤层孤岛煤柱应力集中程度及错层防冲研究

发布时间：2018-03-15 09:44

本文选题：厚硬顶板　切入点：特厚煤层　出处：《中国矿业大学》2016年硕士论文　论文类型：学位论文

【摘要】：冲击矿压是煤矿开采中最为典型的煤岩动力灾害之一。具有厚硬顶板的特厚煤层孤岛煤柱,冲击矿压的危害则更加严重,且相关方面的研究较少。为此,本文通过理论分析、数值模拟及现场实践等方法对厚硬顶板孤岛煤柱冲击矿压发生机理及特厚煤层巷道错层防治技术进行了系统研究。理论推导可知,随着工作面四邻开采条件由实体煤到四侧均采空的不断恶化,顶板内应力集中程度逐渐增加,弯曲变形能积聚速率逐步上升,特别是具有坚硬厚层顶板的孤岛煤柱更易形成具有大面积悬顶的长臂“T”形覆岩结构,其岩层活动范围、剧烈程度大,容易在周围采掘动力扰动作用下顶板破裂形成大能量强矿震震动以应力波的形式对煤柱施加动载荷,而孤岛煤柱在大面积悬顶的夹持作用下已经处于高应力状态,原本较高的静载与动载相叠加超过煤岩体极限强度,导致处于极限状态的煤岩体系统失稳破坏,引起大规模的冲击动力灾害,即由高静载主导—动载诱发的动静载叠加诱冲机理。孤岛煤柱底煤应力场计算结果表明,应力差随底煤深度的增加而减小,应力集中程度和应力差随应力集中系数的改变变化明显。底煤中同时存在应力降低区和应力变化降低区,其可分别表示为0.1q应力和1%应力变化率等值线包络外的区域。而非均布应力是导致巷道支护结构损坏,巷道变形的主因之一,因此错层巷道应布置在应力降低区和应力变化降低区的叠加区域以内。定义0.1q和1%等值线分别为底煤应力降低区和应力变化降低区边界,其与竖直线之间的夹角则定义为应力降低角kq和应力变化降低角sq。应力集中系数k与二者线性正相关,且在k11时,k sq(27)q,因此多数情况应以sq为综合应力影响角f,合理错距为1 2 0l(28)(h(10)h)tanf-x。并以1210孤岛面两巷错层布置工程实践验证了错距计算的合理性。通过FLAC3D数值模拟计算得到1210孤岛煤柱和下山孤岛煤柱的应力集中系数分别为3.8和2.8,验证了孤岛煤柱应力集中程度高、冲击危险性强的结论。通过对各方案的围岩应力及变形情况分析对比发现专用回风巷错层布置方案处于上方采空区的应力降低区下,巷道围岩应力及变形量要远小于其他各方案,对于防冲十分有利。以孟巴矿1108孤岛面冲击事故为背景分析了厚硬顶板孤岛煤柱冲击发生的机理,结合1210孤岛面两巷错层布置工程实例,验证了错层防冲技术的合理性与优越性。
[Abstract]:Rock burst is one of the most typical coal and rock dynamic disasters in coal mining. With thick and hard roof thick coal seams with isolated island pillar, the impact pressure is more serious, and the related research is less. Numerical simulation and field practice have been carried out to study systematically the mechanism of rock burst and the prevention and cure technology of roadway dislocation in thick coal seam by means of thick and hard roof isolated island coal pillar. With the deterioration of mining conditions from solid coal to four sides of the face, the degree of stress concentration in the roof increases gradually, and the accumulation rate of bending deformation energy increases gradually. In particular, the isolated island coal pillar with hard and thick roof is more likely to form a long-arm "T" overburden structure with a large area of suspended roof, which has a wide range of strata activity and a large degree of intensity. It is easy to crack the roof under the action of the surrounding mining dynamic disturbance to form a large energy strong mine earthquake vibration to exert dynamic load on the coal pillar in the form of stress wave, while the isolated island coal pillar is already in a high stress state under the action of a large area of suspended roof. The superposition of static load and dynamic load exceeds the limit strength of coal and rock mass, which leads to the instability of coal and rock mass system in the limit state and causes large-scale impact dynamic disaster. The stress field calculation results show that the stress difference decreases with the increase of coal depth. The degree of stress concentration and stress difference change obviously with the change of stress concentration coefficient. It can be expressed as the area outside the isoline envelope of 0. 1q stress and 1% stress change rate, and non-uniform stress is one of the main causes of roadway support structure damage and roadway deformation. Therefore, the staggered roadway should be arranged within the superposition area of the stress reduction area and the stress change reduction area. The boundary of the 0. 1q and 1% isolines is defined as the bottom coal stress reduction area and the stress change reduction area, respectively. The angle between it and the vertical line is defined as the stress reduction angle KQ and the stress change reduction angle sq.Stress-concentration factor k is positively correlated with the two factors. In most cases, sq should be taken as the comprehensive stress influence angle f, and the reasonable error distance is 120 l0 / 28 / 10 / 10 / h ~ (tanf-x). The rationality of the calculation of the fault distance is verified by the engineering practice of the layout of two roadways on the 1210 isolated island surface. The calculation is obtained by FLAC3D numerical simulation. The stress concentration factors of Gudao coal pillar and Xiashan Gudao coal pillar are 3.8 and 2.8, respectively. It is verified that the stress concentration degree of Gudao coal pillar is high. Through the analysis and comparison of the surrounding rock stress and deformation of each scheme, it is found that the staggered layer arrangement of the special return air roadway is under the stress reduction area of the upper goaf. The stress and deformation of surrounding rock of roadway are much smaller than those of other schemes, which is very beneficial to anti-scour. Based on the impact accident of 1108 isolated island surface in Mengba Mine, the mechanism of impact of thick and hard roof isolated island coal pillar is analyzed. The rationality and superiority of the anti-scour technology of the staggered layer are verified by the example of 1210 isolated island plane two roadway staggered layer arrangement engineering.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD324

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