Coalbursts in China: Theory, practice and management

Coalburst is one of the most serious disasters that threaten the safe production of coal mines, and this disaster is particularly serious in China. This paper presents an overview of coalbursts in China since 1980s. From the "stress and energy" and "regional and local" perspectives, the achievements in the theory, practice and management of coalbursts in China are systematically summarized. A theoretical system of coalbursts has been formed to reveal the deformational behavior of coalbursts and explain the mechanism of coalbursts. The occurrence conditions of coalbursts are put forward and the critical stress is obtained. The stress index method for risk evaluation of coalbursts before mining is proposed, and the deformation localization prediction method of coalbursts is put forward. The relationship between energy release and absorption in the process of coalbursts is found, and the prevention and control methods of coalbursts, including the regional method, the local method and support, are presented. The safety evaluation index of coalburst prevention and control is put forward. The integrated prevention and control method for coal and gas outbursts is proposed. The prevention and control technology and equipment of coalbursts have also been developed. Amongst them, the distribution law of the critical stress in China coalburst mines is discovered. The technology and equipment for monitoring, prevention and control of coalbursts, as well as for integrated prevention and control of combined coalbursts and other disasters, have been developed. The energy-absorbing and coalburst-preventing support technology for roadways is invented, and key engineering parameters of coalburst prevention and control are pointed out. In China, coalburst prevention and control laws and standards have been developed. Technical standards for coalbursts are formulated, statute and regulations for coal mines are established, and regulatory documents are promoted.

防止岩爆危害的工程方法

随着矿业、隧道等地下工程的开挖深度、规模和数量的增加,与岩爆(煤爆)相遇的机会日益增多,这也就对施工现场的安全造成了更严重的危害。岩爆(煤爆)是一种突发性的地质灾害,是由复杂的自然地质作用和人为地质作用形成的。为了探求有效的防止岩爆(煤爆)危害的工程方法,本文结合现场的工程实例和实验研究进行了从宏观到微观的理论分析,在摸清地质背景、发生条件和范围的基础上,发现了岩爆能量转化的基本规律,用有效的工程措施来防止其危害的发生。

顶板初始损伤对煤岩组合体破坏性态及能量演化的影响

采用CASRock对煤岩组合体开展单轴压缩破坏过程数值模拟试验,分析顶板初始损伤对煤岩组合体力学行为的影响。结果表明:(1)顶板初始损伤对煤岩组合体力学行为的影响程度与顶板中初始裂隙的几何分布密切相关,随着裂隙与水平面夹角增大,煤岩组合体由延性破坏向脆性破坏转变,同一裂隙倾角下,随着裂隙长度增加,煤岩组合体由脆性破坏向延性破坏转变,且裂隙与水平面夹角越小、长度越长、距离煤层越近对煤岩组合体力学行为影响越大,越能主导煤岩组合体的力学行为,煤体越不易发生破坏;(2)顶板含多裂隙时裂隙主导煤岩组合体力学行为能力更强,当顶板初始损伤较严重时,初始的裂隙网络会形成应力集中区,导致其对煤岩组合体力学行为影响能力变强;(3)单轴压缩条件下,劈裂破坏是主要的破坏形式,顶板初始损伤对煤岩组合体强度与变形能力的提升作用较强,当顶板裂隙对煤岩组合体力学行为影响较大但不主导其力学行为时,其释放能量效果较好,顶板初始损伤在一定程度上增强了对煤层的保护效果。

重复冲击特厚煤层巷道围岩裂隙演化及破坏特征

针对特厚煤层巷道围岩在重复冲击动载作用下发生大变形甚至垮冒堵巷的控制难题,基于深部巷道围岩破坏机理与岩石冲击动力学理论,研究了多次冲击扰动下特厚煤层巷道裂隙演化及围岩破坏特征,建立了重复冲击巷道围岩弹塑性理论破坏模型,阐明了动静载叠加条件下特厚煤层巷道围岩弹塑性区及破碎区的动态演化规律,计算了某典型巷道重复冲击载荷下围岩松动破坏的极限范围.推导了在动静载叠加作用下巷道围岩弹塑性区、破碎区范围平衡方程,得到了破碎区与塑性区范围均与巷道半径、覆岩压力及冲击震动强度呈正相关,与巷道围岩支护强度呈负相关,巷道断面半径对围岩松动圈范围影响较大;分析了围岩裂隙演化及破坏特征,张拉裂隙的衍生是浅部破碎区发育的重要原因,剪切滑移裂隙的扩展是深部塑性区发展的主导因素;阐明了重复冲击特厚煤层巷道破坏及控制机理,当冲击震动波传递至巷道时,松散脆质煤层中原生发育的大量裂纹迅速扩张,裂隙带相互交错、贯通,瞬间造成巷道围岩承载稳定结构破坏;工程算例某矿巷道围岩破碎区与塑性区深度范围,提出了重复冲击地压巷道防冲支护路径,采用“硬顶预裂+煤体双卸+锚网强支”技术提高了重复冲击震动条件下巷道围岩稳定性.研究结论和成果对重复冲击矿震巷道围岩稳定性控制有积极参考和借鉴意义.