【作者】 李小琴；

【导师】 李文平；

【作者基本信息】 中国矿业大学 ， 地质工程， 2011， 博士

【摘要】 突水是我国煤矿存在的重大安全隐患,随着我国煤炭产量的不断增加,煤矿开采深度增大,多煤层开采等原因,一种新的顶板水害类型——覆岩离层水水害开始出现,并由于其具有瞬时水量大、突水征兆不明显、危害大等特点而逐渐引起重视。目前,国内外研究成果主要集中于离层形成机理、分布规律及离层注浆减沉的工程应用,对于离层水形成条件及其涌突水机理等研究很少。论文采用理论分析、现场试验、室内试验、数值模拟和工程实践应用等研究方法,以阐释淮北海孜矿5.21特大离层水涌突机理为主旨,在分析离层水害事故发生的背景条件基础上,围绕“离层的形成→离层水的形成→离层水突出”这一主线,对坚硬覆岩下重复采动离层水形成及涌突机理进行了深入的理论研究和探讨,提出了离层水防治的关键技术,并用于生产实践。取得以下成果:(1)利用地面钻探、注水流量测井、钻孔电视和离散元数值模拟综合研究了10煤、7煤重复采动情况下7煤覆岩离层的发育规律:1049面的开采破坏了7煤上覆地层的自然状态,火成岩底界、厚砂岩层内出现离层,随后745面的重复采动,使得先期形成的7煤覆岩中的离层规模进一步增大。由于厚砂岩本身为含水层,对其内的离层补给形成了“积水离层带”;其余发育在隔水层内的离层裂隙,则形成“真空离层带”。(2)提出离层水的形成需要具备4个基本条件:a、可积水离层——离层的发育位置位于导水裂隙带之上;b、离层周边存在补给水源;c、离层空间持续时间足够长;d、离层周围岩体的渗透能力较强。(3)考虑卸荷作用对渗透的影响,进行了人工制作裂隙砂岩试样卸除围压直至破坏的渗透试验;考虑岩体裂隙的影响,对由Monte-Carlo方法生成的砂岩复杂裂隙网络模型,进行了固定应力比、变应力比的渗流离散元模拟试验;卸荷渗透试验和裂隙网络渗流数值试验结果表明砂岩的渗透能力足以在较短时间形成大量的离层水,这是支持突水水源为离层水观点的重要依据。并根据渗流REV模拟结果,利用等效连续介质理论对砂岩水的渗流进行描述,得出了砂岩含水层水汇入离层水量的理论公式。(4)通过自行设计的动水压力模拟试验,发现岩石破坏瞬间会产生较高的动水压力。借助动水压力这一概念,将火成岩冲击动力作用下离层水突出危险性评价这一动力问题拟静力化,转换为采用动水压力计算突水系数进行危险性评价的问题,证实了突水事故必然发生。(5)采用物理模拟试验、离散元数值模拟方法对火成岩突然破断对岩层的冲击破坏效应进行了研究,结果表明,若火成岩发生突然破断,其冲击震动作用会使位于5.21突水位置上方的厚砂岩离层下位岩层的水平、垂直应力超过其强度能力、出现较大的变形速度、发生持续增大的水平、垂直变形量,瞬间发生失稳破坏,形成动力突破带,与其下的导水裂隙带沟通,整体构成5.21突水通道。(6)利用弹性理论、波动力学及弹性应力波等基础理论,对火成岩突然破断瞬间突破离层水体下完整岩层形成动力突破带的这一动力过程进行了理论推导,提出了动力突破带的理论表达式。(7)提出了坚硬覆岩下离层水突出的工程地质模型,指出离层积水的形成是发生离层水害事故的最根本、最重要的原因。由此提出防治离层水的关键技术是施工指向工作面外的离层水截流孔、指向预计离层发育位置的离层水导流孔来截断离层水补给水源、超前疏放离层水。并应用于745面恢复生产区段,实现了安全高效生产。该论文有图79幅,表22个,参考文献262篇。更多还原

【Abstract】 Water inrush threats the coal safe production in China. Recently, because of the raise of the production of the coal, the raise of the mining depth and the multi-seam mining, a new type of the roof water disaster, the water in roof bedding separation inrush appears. It has characters of large instantaneous water quantity, no obvious Symptoms of the water inrush and great harmfulness, which receives more concerns in recent years. At present, the research work focuses on the formation mechanism of the bed separation, distribution regularity and the engineering applications of subsidence reduction with grouting in the bed separation. Few research work has been done on the formation conditions and the inrush mechanism of the water in bed separationBy theory analysis, field tests, experiments in the lab, numerical simulation and application in practice, for the purport of the description the inrush mechanism of the water in bed separation in Haizi Colliery, this thesis deeply studies the formation and inrush mechanism of the water in bed separation under the hard overburden due to repeated mining. The study work is centering on the formation of the bed separation, the formation of the water in bed separation and the inrush of the water in bed separation, based on analyzing the background conditions the inrush disaster of the water in bed separation. the key control technology of the water in bed separation is presented, which has been used in practice. The following results are obtained.(1)With surface drilling, the well logging of the injection flow, borehole televiewer and discrete element method simulation, the development rule of the bed separation in Coal 7 overburden is studied due to the Coal 10 and Coal 7 repeated mining. The natural state of the Coal 7 overburden damaged after the mining of the 1049 work face. The bed separation in the thick sandstone occurs at the bottom of the igneous rock. The bed separation expands due to the repeated mining of the 745 work face. The thick sandstone is the aquifer, which promotes the accumulation of the water in bed separation by supply the water. The other bed separation is located in the aquifuge and becomes the vacuum bed separation.(2)The 4 basic conditions of the formation the water in bed separation are presented. The first, the bed separation is above the water flowing fractured zone. The second, the recharge water source is around the bed separation. The third, the bed separation sustains long enough. The last, the surrounding rock has high permeability.(3)To study the unloading influence on the rock permeability, the man-made fractured rock samples permeability tests are done with unloading the confining pressure to failure. Used random fracture network model by Monte-Carlo method, the numerical simulation is done to study the fixed stress ratio, variable stress ratio. The results show that the permeability of sandstone is big enough to accumulate much water in bed separation in some time. It is important. Used discrete element method, the permeability REV is decided as 8m. The mathematical model of the water flow in thick sandstone aquifer injection into the bed separation is obtained by describing the permeability of the water in sandstone with equivalent continuum theory.(4)Whether the inrush of the water in bed separation occurs is judged by the water inrush coefficient method. Based on excess hydrostatic pressure test’s results, the water inrush coefficient of the water in bed separation loaded by the igneous rock impact is calculated. If the calculated value is higher than the critical water inrush coefficient, the water inrush must occur.(5)The impact damage effect of the igneous rock sudden failure is studied by similar model test and discrete element method. The results show that if the igneous rock sudden failure occurs, its impact shock effect causes the horizontal and vertical stress of the strata under the thick sandstone bed separation higher than the capacity strength, and the high deformation velocity occurs. The horizontal and vertical deformation increases continuously, which cause the sudden failure and connects with the lower water flowing fractured zone. The inrush channel of the 5.21 Water Inrush Disaster forms.(6)Using elastic theory, wave mechanics and elastic stress wave theory, theoretical derivation on the dynamic process of the igneous rock sudden failure damaging the lower strata is done. The calculation formula of the dynamic breakthrough zone is presented.(7)The engineering geological model of the water in bed separation under the hard overburden is proposed, which points that the accumulation of the water in bed separation is the critical reason of the inrush disaster of the water in bed separation. Based on the research results, the control technology of the water in bed separation is presented, which contains using the water closure and diversion borehole of the water in bed separation to truncate the recharge the water in bed separation and advance dewatering the water in bed separation. The technology was used in the resumption production of the 745 workface of Haizi Colliery, which insures safety and high effective product.The thesis has 79 figures, 22 tables and 262 references.更多还原