离层注浆控制冲击矿压危险机理探讨

煤层上覆坚硬厚层岩层组成的主关键层对冲击矿压的发生具有强烈的影响,主关键层岩层的剧烈活动是冲击矿压发生的集中区域,而且震级也高;冲击矿压的发生需要煤层及其周围岩层中聚集大量的弹性能外,还需要主关键层破裂等释放的外部能量;该外部能量与岩层厚度的平方、抗拉强度的2．5次方成正比;破断中心距巷道工作面越近、释放的能量越大,传播到巷道工作面处的能量越大,越容易引发冲击矿压。因此,可采用覆岩离层注浆等技术手段保证覆岩主关键层的长期稳定,消除主关键层岩层破断引发的冲击矿压危险。     

顶板岩层对冲击矿压的影响规律研究

采用模拟试验方法研究了顶板岩层对煤体应力状态的影响,并根据震动能量对煤体的破坏效应和在岩体中的传播衰减规律,从能量角度分析了煤层上方不同厚度和强度的顶板岩层对煤体冲击的影响程度.结果表明,顶板释放的能量与岩层强度呈对数关系、与顶板厚度呈指数关系,坚硬、厚层顶板岩层会对煤体产生更为强烈的扰动,使冲击矿压危险性明显升高.另外,具有一定厚度和强度且距离煤层较近的老顶岩层运动产生的冲击载荷对煤体的影响作用较大.某矿一个工作面的冲击矿压防治工程实践表明,对该煤层上方的顶板岩层实施爆破弱化处理技术措施后,可有效降低工作面回采过程中的冲击危险性.     

高构造应力区矿震规律研究

利用华亭煤矿微震监测系统,研究了处于褶皱区域矿震灾害严重的250102工作面开采过程中矿震时空演化规律.结果表明:强矿震大部分发生在向斜轴部,向斜轴处冲击动力灾害危险高于其他位置.向斜轴部强矿震周期短,频次高;强矿震发生前,震动次数持续上升,但震动能量出现"平静"或下降趋势,可作为高应力向斜构造区强矿震预测的前兆信息.高构造应力区强矿震波形持续时间长,频谱呈高频多峰分布,破坏性大.降低产量,工作面匀速推进与超前卸压相结合,能控制高构造应力区矿震灾害强度.     

顶板岩层诱发冲击的冲能原理及其应用研究

针对顶板岩层对煤体冲击的影响作用机理,采用实验室物理模拟试验、UDEC 4.0离散元数值模拟试验、理论分析和工程实践验证这4种方法进行了研究,提出了煤岩冲击破坏和顶板岩层诱发冲击的冲能原理以及冲击破坏判别准则,并在工程实践中进行了应用和验证.根据煤岩冲击破坏动能试验和煤岩破坏的应力-应变曲线能量演化规律分析结果,具有冲击倾向性的煤岩样在载荷作用下破坏时将产生强烈震动和脆性冲击型破坏,破碎的煤块具有一定的初始动能并以一定的初速度脱离煤体,把这些煤岩样冲击破坏时碎块冲出的动能定义为该煤岩样的冲能,即冲出的能量,从而建立了煤岩冲击破坏的"冲能原理"和"冲能判别准则".通过岩板断裂震动物理模拟试验和数值模拟试验研究,得到顶板断裂过程中可产生强烈震动冲击载荷、致使煤岩破坏时的冲能、冲击危险性升高的研究结果;顶板断裂震动持续时间与顶板厚度呈线性关系,对煤体的震动损伤与顶板厚度呈乘幂关系,从极限悬顶长度的一半开始,煤体的冲击危险性显著升高,顶板岩层释放的能量与岩层强度呈对数关系;岩层运动产生的动能和释放的总能量分别与顶板厚度呈指数和乘幂关系.将顶板岩层诱发冲击矿压的机理分为处于稳定态岩层的"稳态诱冲机理"和处于运动态岩层的"动态诱冲机理"2种类型,岩层的"稳态诱冲机理"是指当顶板岩层不发生大规模破断或滑移垮落时,由岩层内部储存的弹性能的突然释放而导致的煤体冲击机理,稳态诱冲机理研究确定了影响煤岩破坏的2个重要初始参量--煤体的应力基数P.和能量基数U.,应力基数决定了破坏的条件,能量基数决定了破坏时释放能量的大小."动态诱冲机理"是指由顶板岩层发生大规模破断或滑移垮落产生的强烈震动和释放的大量冲击能等动载荷导致的煤体冲击破坏机理,分析了顶板岩层断裂和滑移的震动特性,坚硬厚层项板岩层在诱冲方面的作用主要表现在以较高频率的冲击载荷方式对煤体造成损伤;稳态岩层和动态岩层在诱发煤体冲击的时候都以动态的形式释放能量并参与到煤体破坏时的冲能当中,在满足冲能判别准则的情况下均可诱发冲击矿压,由此形成"顶板岩层诱发冲击矿压的冲能原理".基于岩体介质中能量传播规律和岩层影响冲击危险性的不同程度,提出了岩层影响下的煤体冲击危险"诱冲关键层"判别准则和诱冲关键层的判断方法,按照传播至煤体能量的大小给出了岩层的诱冲系数点Kb=E'k/Er0.和对应的能量值,用来表征岩层诱发冲击矿压的可能性大小.2个具有冲击危险的煤矿通过控制顶板岩层和控制煤体以降低"岩层-煤体"系统冲能进行冲击矿压防治的工程实践验证了本文关于"项板岩层诱发冲击矿压的冲能原理"研究结果的实用性与可靠性.     

平煤十一矿微震监测系统优化布置及应用

根据十一矿己二下山采区的采掘接替关系,提出了时空预测技术,确定了冲击地压重点防治区域.对微震监测站布置进行了优化,共布置了14个地下测站和2个地面测站.根据矿震监测记录,分析了微震信号的频谱特征和能量特征.结果表明,距矿震地点较近的震动频谱范围较宽,能量较大,低能量的震动有利于能量的释放,强矿震前会出现矿震能量和次数的静默期,最后,建立了十一矿强矿震危险监测防治体系,提出了冲击地压的解危措施.     

巨厚砾岩层下综放工作面冲击地压危险性评价和矿震发生特征分析

为有效监测和防治综采工作面冲击地压事故,以耿村煤矿巨厚砾岩层下综放工作面为工程背景,采用综合指数法评价综放工作面冲击地压危险性,利用微震监测结果研究综放工作面回采期间矿震特征。结果表明：（1）13230综放工作面冲击危险性指数为0.65,属于中等冲击地压类型;（2）综放工作面回采期间矿震主要发生在工作面前方顶底板煤岩体中,工作面处于“见方区”时发生矿震的频次、最大能量和总能量均明显高于“非见方区”的,“见方区”矿震的震源主要位于工作面前方中部顶底板煤岩体和运输平巷上帮顶板煤岩体中;（3）综放工作面顶板周期来压期间通常伴随大能量的矿震事件。研究结果可为耿村煤矿综放开采冲击地压监测和防治提供参考。     

乌东煤矿近直立煤层冲击地压机制研究

以乌东煤矿南采区为工程背景,运用工程实践、数值模拟、理论分析等方法,对近直立煤层冲击地压机制展开研究.结果表明:顶板和岩柱强矿震频发,形成强动载扰动;近直立煤层、顶板及岩柱在开采水平附近形成高应力集中区,应力集中程度与水平应力、岩柱"撬动"及顶板"弯曲"效应相关.水平应力、岩柱"撬动"及顶板"弯曲"效应作用使B_(3+6)煤层在开采水平附近形成高静载集中区域,该区域在岩柱和顶板强矿震与采动多重扰动作用下失稳并释放能量导致B_(3+6)工作面的两顺槽发生冲击地压.     

大采深条带开采坚硬顶板工作面冲击矿压治理研究

为了解决大采深条带开采坚硬顶板工作面的冲击矿压问题,以古城煤矿2106工作面为例,采用现场分析、实验室试验、数值模拟的方法对其发生机理进行了研究.结果表明在此条件下开采时发生的冲击矿压与煤岩性质、采深、坚硬顶板厚度及顶板的周期来压有密切关系.当冲击矿压发生的煤层具有强冲击倾向性,煤层硬度系数大于3、采深900 m以上、顶板岩层坚硬且厚度大于20 m时,冲击矿压发生具有突然性和猛烈性;主要发生在顶板周期来压期间、超前支护50m范围内,此时工作面的CH4和CO气体含量同时升高.对此提出了钻屑法等预测预报的方法和煤体爆破卸压与柔性支护等治理措施.     

矿震扰动下采区煤柱应力偏量集中区诱冲机制及防治方法

以张双楼矿西一采区生产地质条件为工程背景,基于应力偏量、等效应力、Mises强度准则、能量释放速率分析了煤岩冲击失稳的充要判别准则,揭示了采区煤柱覆岩结构、应力偏量、矿震事件随工作面回采演化规律,并探讨了矿震扰动下采区煤柱冲击危险防治方法.结果表明:煤岩冲击失稳充要条件为开采活动及矿震扰动引起的应力偏量超过煤岩体强度极限,且单位时间内煤岩系统释放弹性能量与矿震应力波输入能量之和大于煤岩系统稳态破坏消耗能量;随着采区工作面持续开采,采区煤柱两侧覆岩形成"T"型悬臂结构并不断损伤破坏;以标量应力偏量第二不变量J2表征应力偏量σ′_(ij),煤柱区应力偏量前期呈"M"型分布并逐渐向单峰型转变,屈服破坏区逐渐向煤柱中部扩展;以矿震频次、能量、震源位置表征应力波扰动σ_(ij)~d,矿震扰动以低能量事件为主,且主要集中于正回采工作面及采区煤柱区域.根据分析结果,提出矿震扰动下采区煤柱切顶爆破、扩大采区煤柱宽度、跨上山开采、大直径钻孔卸压等防冲方法.     

基于厚硬关键层破断的地面震动损害边界研究

在对近地表厚硬关键层运动引起地面震动案例分析的基础上,综合厚硬关键层破断及能量传播规律,提出了"震动损害边界"的观点,并以质点震动速度作为震动损害的主要评价指标,初步建立了矿震诱发地面震动损害的评估方法.根据厚硬关键层破断诱发强矿震的基本条件,提出了矿震引起地面震动损害的防控思路:1)改变矿震孕育的条件;2)减小一次矿震释放的能量.通过某矿16101工作面开采实践,取得了良好的效果.     

Rock burst risk evaluation based on equivalent surrounding rock strength

On-site investigations consistently show that the rock burst inherent to coal seams varies greatly with coal seam thickness. In this study, impact factors related to coal seam thickness and surrounding rock strength were analyzed and a corresponding rock burst risk assessment method was constructed. The model reflects the influence of coal seam thickness on the stress distribution of surrounding rock at the roadway. Based on the roadway excavation range, a stress distribution model of surrounding roadway rock is established and the influence of coal seam thickness on rock burst risk is analyzed accordingly. The proposed rock burst risk assessment method is based on the equivalent surrounding rock strength and coal seam bursting liability. The proposed method was tested in a 3500 mining area to find that it yields rock burst risk assessment results as per coal seam thickness that are in accordance with real-world conditions. The results presented here suggest that coal seam thickness is a crucial factor in effective rock burst risk assessment.     

A review of energy associated with coal bursts

A coal burst is defined as a rapid expulsion of coal(and potentially gas) from the boundary of the roadway. Rock and coal fractures together with micro seismic vibration is a common occurrence during mining, however, it is very uncommon for coal and rock to be propelled into the roadway. Irrespective, such occurrences do occur and appear to require significantly more energy than is available from strain energy release during coal cutting. The sources of energy which can contribute to the propulsion of coal from the face or ribs are typically strain energy from the surrounding ground, seismic energy from a rapid rupture of the ground in the vicinity, or rapid expansion of gas from within the burst source area. The aim of this paper is to briefly review the bursts which may be related to strain energy, seismic energy and gas energy.     

坚硬顶板型冲击矿压灾害防治研究

针对兖州矿区济三煤矿6303工作面的冲击矿压问题，分析了冲击矿压发生的主要原因及影响因素．根据现场条件和数值模拟分析，提出了采用顶板爆破解除冲击矿压危险的技术措施，并确定了爆破参数．采用矿用钻孔窥视仪并配合电磁辐射法和钻屑法对爆破进行了效果检验．结果表明，通过顶板爆破措施可以破坏工作面上方坚硬厚层砂岩顶板的完整性，提前释放顶板聚集的弹性能，减弱和消除了工作面的冲击矿压危险，胜，保证了工作面的安全生产．现场实践证明，该项技术对具有坚硬顶板型冲击矿压的防治效果明显．     

Numerical simulation study on hard-thick roof inducing rock burst in coal mine

In order to reveal the dynamic process of hard-thick roof inducing rock burst, one of the most common and strongest dynamic disasters in coal mine, the numerical simulation is conducted to study the dynamic loading effect of roof vibration on roadway surrounding rocks as well as the impact on stability. The results show that, on one hand, hard-thick roof will result in high stress concentration on mining surrounding rocks; on the other hand, the breaking of hard-thick roof will lead to mining seismicity, causing dynamic loading effect on coal and rock mass. High stress concentration and dynamic loading combination reaches to the mechanical conditions for the occurrence of rock burst, which will induce rock burst. The mining induced seismic events occurring in the roof breaking act on the mining surrounding rocks in the form of stress wave. The stress wave then has a reflection on the free surface of roadway and the tensile stress will be generated around the free surface. Horizontal vibration of roadway surrounding particles will cause instant changes of horizontal stress of roadway surrounding rocks; the horizontal displacement is directly related to the horizontal stress but is not significantly correlated with the vertical stress; the increase of horizontal stress of roadway near surface surrounding rocks and the release of elastic deformation energy of deep surrounding coal and rock mass are immanent causes that lead to the impact instability of roadway surrounding rocks. The most significant measures for rock burst prevention are controlling of horizontal stress and vibration strength.     

Mechanism of energy limit equilibrium of rock burst in coal mine

With the increase of mining depth, the effect of rock burst on coal mining is becoming more and more obvious and the rock burst mechanism becomes more and more complicated. Scholars from many countries had put forward different mechanisms, but no one gave a reasonable explanation to the mechanism of rock burst. In this paper, based on the energy theories, we studied the energy limit equilibrium (ELE) of coal mine rock burst. The coal seam with rock burst is divided into energy limit equilibrium zone (ELEZ) (A) and elastic zone (B); we also determined the position where the rock burst occurs, including the roof and floor of coal seams; in addition, we derived the limit width of ELEZ and the mathematic relationship between the limit width and occurrence mechanism of rock burst: the energy difference function (EDF), w(x) = wJ - wp because first-order derivative w'(x), is less than 0. So EDF is a monotonically decreasing function. The graph of the energy difference function was also determined,through which we analysed the occurrence mechanism of rock burst.     

煤岩动力灾害的弱化控制机理及其实践

煤岩动力灾害的实质是能量积聚与耗散的自组织临界过程，当煤岩体中所积聚的弹性能达到其极限冲击能时，就会发生冲击矿压．实验室研究发现，弹脆性煤体是能量积聚与耗散的主体，顶板关键层（坚硬厚层砂岩顶板）的运移则会导致能量积聚与耗散，加速失去动态平衡．以煤岩冲击倾向性与顶板强度及厚度的关系为基础，依据能量积聚与耗散理论，提出了煤岩动力灾害的强度弱化机理，即通过钻孔卸压与深孔卸压爆破来弱化煤岩体的强度，降低煤岩体的聚能能力，释放煤岩体中所积聚的大量弹性能，使得煤岩体中所积聚的弹性能达不到最小冲击能，同时利用电磁辐射监测仪来检验煤岩体强度弱化治理的效果，以达到消除或降低冲击危险的目的．通过在三河尖煤矿9202高冲击危险工作面的生产实践，充分证明了这种技术的有效性．     

煤岩体中弹性比能分布的有限元计算分析

冲击地压发生的前提是矿山井巷和采场周围的煤岩体中储存了足够的弹性能．摸清围岩体中弹性能的分布规律是有效地进行冲击地压预测预报的前提，文中探讨了井巷和采场围岩体处于弹塑性变形状态下其弹性比能的计算方法，提出了用有限元法分析计算处于弹塑性变形状态下的煤岩体中弹性比能分布的理论与方法，以及产生冲击地压的弹性能判据．结果表明，蝶层巷道两帮煤体中弹性比能的最大值与采深的平方近似成正比，与其弹性模量近似成反比．对鲁村煤矿2217区段运输平巷的具体条件进行的有限元计算分析表明，该巷道不满足产生冲击地压的条件，与现场实际情况相吻合．     

基于微震成像的采煤工作面应力异常监测

为了实现对深井采煤工作面的冲击地压灾害预防,采用微震走时成像技术,监测采煤工作面的应力异常.根据系统要求布置传感器台网,实现工作面全覆盖;采用层状模型分析地震波传播路径,计算地震波传播速度,利用子空间分阶段求解的方法进行反演,实现对监测区域的地震波走时层析成像;结合地震波速度和岩石所受应力的关系,达到研究采煤工作面应力异常的动态分布及变化特征的目的.试验结果表明：工作面推进时,煤层顶板高应力异常达到最大,工作面前方的高应力异常区动态变化范围较大,工作面后方存在较稳定的地震波低速异常,利用微震成像技术可以有效地监测地震波速度异常区域的范围及变化特征.     

Spatiotemporal analysis of elastic and inelastic deformations in roof-rocks from seismological observations

The spatiotemporal analysis of seismic zones characterised by the scattering and accumulation of strain energy in the roof-rocks of the excavated longwall panel where inelastic or elastic deformations occurred during hard coal seam mining is discussed. The studied longwall panel was designed to utilize the effect of partial stress relaxation caused by the earlier extraction of the coal seams located above. A full seismic moment tensor and spectral source parameter analyses were used to obtain information about the degree of inelastic and elastic coseismic deformations. This study also showed that these deformation changes correspond to variation in the Benioff strain release characteristics. Next, analyses of deformation zones were compared with the relationship between radiated energy and the excavated volume of rocks per month. The concept of balanced seismic energy release assumed the exponential increase of released seismic energy with the increase in the volume of excavated rock. Discrepancies between the observed and predicted radiated energies indicated that strain energy in selected zones in the rock mass was either scattered if the prediction was overestimated, or accumulated if underestimated. Moreover, the study showed that elastic deformation in one zone can lead to inelastic deformation in the same zone.