Research into stope roof control of compound roof by solid backfilling mining

Based on the analysis of the failure characteristics and backfilling effect of the compound roof at 1801 backfilling workface in Taiyuan coal mine,China,we propose a method of controlling the presubsidence of a compound roof by using pre-stressed bolts to improve the backfilling ratio of the workface so as to maintain the global stability of the stope roof.In addition,PHASE simulation software was employed to analyze the influence law of pre-stressing force,length,and interval on roof subsidence at the workface.On the basis of the numerical simulation results,a model for calculating the pre-stressing force and length of the bolts,the interval between the bolts,as well as roof subsidence at the workface,was established by using SPSS regression analysis software.Moreover,the research results were applied successfully to the 1801 filling workface.According to the monitoring data of roof closure,it was found that the final subsidence value for the goaf roof was 350 mm and the filling ratio at the workface was 86%,which could fully meet the demand for safety production at the workface.The safe and effective control of the stope roof was therefore realized,which achieves the goal of safe and efficient backfilling mining under a compound roof.

Numerical research on stability control of roofs of water-rich roadway

In order to study the strength-weakening law of roofs of water-rich roadway, this study used FLAC software, and simulated and analyzed the failure characteristics of the surrounding rock of water-rich roadway under the condition of different cross sections and support parameters, finally obtained the stress distribution of the principle stress of the roadway as well as the displacement variation of its surrounding rock. Results indicate that the roof stability of roadway with semicircular cross section is better than the roadway with inclined rectangular cross section under water-rich condition. Besides, the surrounding rock deformation of roadway under the action of water shows a pronounced increase compared to the roadway without the action of water due to the fact that water will obviously weaken the surrounding rock of roadway, especially its roof. It is very beneficial to control roof stability of water-rich roadway and guarantee the roadway stability during its service life by improving the pretension of bolt and cable as well as decreasing inter-row spacing of the bolt.

Roof filling control technology and application to mine roadway damage in small pit goaf

To recover coal resources that have been damaged by traditional mining methods and ensure stability of the lower roadway in a small pit goaf,the goaf area must be filled and reinforced.In this research,the 1202 working face of the Hanzui mine is considered as an example for classifying the roof of the mining tunnel under the small kiln destruction zone,the effect of the goaf on the roadway is determined based on the radio tunnel penetration method,a mechanical model to determine the roof filling control mechanism was established,and the duct foaming system and roof filling process were designed.The results show that the scope and degree of influence of the goaf on the mining lane are large,but safe tunneling can be ensured through the use of a steel shed and advanced grouting techniques.When the roof conditions are not similar,materials with different filling heights and filling strengths can be used to control the roof filling of the roadway.By combining field experience and laboratory tests,it was determined that a high-foaming material with a water-cement ratio of 1:0.6,a suitable high-foaming additive,and a water volume ratio of 1:30 is cost-efficient for filling and meets the filling strength requirements.Finally,the reliability of the proposed technology was verified by field experiments,which provide a reference for filling operations in similar mines.

Analysis and control on anomaly water inrush in roof of fully-mechanized mining field

从水流入的矿房顶的探穴由于异常压力是能在生产期间发生在矿的主要灾难和事故之一。房顶水流入能触发大量房顶倒塌，引起从打破房顶支持的主要事故当时探穴。这些失败充满井并且做很多损坏到矿并且危及矿安全。我们的目的到在工作的 #6301 压碎支持的水流入的异例在 Yanzhou 采矿组的 Jisan 煤矿面对的分析。通过到房顶的水流入的信息，损坏由构造运动引起了，损坏的信息在矿桥墩关于压力的分发由房顶倒塌和理论引起了，我们调整工作的脸的长度和打开离开的位置的忠告相对切了到富有的水区域。在异常房顶压力的情况中，我们应该开发一个州的方程估计有鈥渢r ansferring 的预防措施摇横梁鈥 ? 理论。同时，我们在宝库改进排水设备和保证的足够的水保留的能力。这些都是主要技术对异常的水流入在房顶引起的事故保证控制和预防，因此在一个煤矿的生产过程保证安全。

Preventing roof fall fatalities during pillar recovery:A ground control success story

For decades, pillar recovery accounted for a quarter of all roof fall fatalities in underground coal mines.Studies showed that a miner on a pillar recovery section was at least three times more likely to be killed by a roof fall than other coal miners. Since 2007, however, there has been just one fatal roof fall on a pillar line. This paper describes the process that resulted in this historic achievement. It covers both the key research findings and the ways in which those insights, beginning in the early 2000 s, were implemented in mining practice. One key finding was that safe pillar recovery requires both global and local stability.Global stability is addressed primarily through proper pillar design, and became a major focus after the2007 Crandall Canyon mine disaster. But the most significant improvements resulted from detailed studies that showed that local stability, defined as roof control in the immediate work area, could be achieved with three interventions:(1) leaving an engineered final stump, rather than extracting the entire pillar,(2) enhancing roof bolt support, particularly in intersections, and(3) increasing the use of mobile roof supports(MRS). A final component was an emphasis on better management of pillar recovery operations.This included a focus on worker positioning, as well as on the pillar and lift sequences, MRS operations,and hazard identification. As retreat mines have incorporated these elements into their roof control plans,it has become clear that pillar recovery is not ‘‘inherently unsafe." The paper concludes with a discussion of the challenges that remain, including the problems of rib falls and coal bursts.

Stability control of water-enriched roofs of coal drifts

Excavation-and-support induced disturbances are likely to make water-enriched roofs to become weathered and fractured.The development and connection of cracks provide new water channels which may result in water loss,seriously affecting the in-tegrity and stability of roofs,leading to incidents of roof fall.Control of water-enriched rocks surrounding coal drifts is quite diffi-cult in China.Based on the practical situation of a water-enriched roof of a coal drift in working face 112201 of the Meihuajing coal mine,we studied the deformation features of surrounding rocks and the development of fractured areas and analyzed the major reasons for the decrease in load-carrying capacity,indicating that the key to maintain roof stability of this kind of coal drift is water retention.In addition,we proposed a staged control technology consisting of:1) surface grouting;2) cable anchor strengthening and 3) roof grouting,which has proven to be successful in this practical application.Our study indicates that,after the problem of water loss from the water-enriched roof had been effectively solved,a combined support system with high performance bolts can maintain the stability of the bearing structure,resulting in the control of roof stability in this kind of coal drift.

Controlling floor heave of extraction opening by reinforcing sides and roof

The effect of reinforcing roof, sides and floor corners to control floor heave of extraction opening was analyzed, It was proved by engineering practice and numerical simulation that reinforcing any part of surrounding rock have certainly control effect for floor heave, in the basis of this, the new way that roof, sides and floor corners were rein-forced to control floor heave was put forward. Contrasting control result of reinforcing floor with this, it is determined that reinforcing is more suitable to control floor heave of extrac-tion opening than reinforcing floor when advancing abutment pressure is in some range.

Overburden fracture evolution laws and water-controlling technologies in mining very thick coal seam under water-rich roof

Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution laws when mining 4#coal seam.Besides,this study researched on the influence of face advancing length,speed and mining height on the height of the water flowing fractured zones(HWFFZ),and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow.Based on those mentioned above,this research proposed the following water-controlling technologies:draining the roof water before mining,draining goaf water,reasonable advancing speed and mining thickness.These water-controlling technologies were successfully used in the feld,thus ensured safely mining the very thick coal seam under water-rich roof.

底板动压巷道压裂弱结构体应力转移控制技术

为了满足煤矿安全生产的需要,许多巷道都会布置在煤层底板中,如部分运输大巷、排水巷道、瓦斯抽采巷道等。采动应力容易造成底板巷道围岩应力升高,加剧底板巷道围岩变形,造成支护永久失效、顶板下沉、巷道底鼓、两帮收敛等破坏。针对此,提出了在应力传递路径上实施水力压裂,在指定的区域制造出一定空间形态的水压裂缝网,形成压裂弱结构体,实现区域范围内的应力转移,从而降低巷道区域范围内的应力,控制巷道的围岩稳定性的控制技术,并通过理论分析及现场工程验证等方式,揭示了底板动压巷道压裂弱结构体应力转移的力学机制,建立了相应的力学模型,对压裂弱结构体的合理位置、范围等影响因素进行了求解。得出:(1)压裂弱结构体使局部应力场发生明显变化,出现应力升高区和应力降低区,应力降低区主要分布在弱结构体与采动应力连线的方向上,主要集中在一个拱形的范围内;由于膨胀效应,在与应力来源垂直的方向上产生应力集中,出现应力升高区。(2)最大主应力变化幅度与压裂弱结构体的长轴长L、短轴长H、到巷道的距离P、与巷道连线的水平夹角β、压裂层的强度C及内摩擦角α、压裂的损伤变量D等有关。其中到巷道的距离P对卸压效果影响最大,损伤变量D对卸压效果影响最小。(3)采用提出的计算方法设计了淮北矿业集团袁店一矿的103运输集中巷的卸压方案,工程应用结果表明,底板动压巷道变形速率明显减缓,验证了底板强动压巷道压裂弱结构体应力转移模型的合理性。

矿井采煤工作面顶板事故防治策略研究

随着中国采煤工作面深度和开采规模不断扩大,顶板事故不断增多,给矿井生产带来了极大的影响。如何有效防治顶板事故,成为了亟须解决的问题。论述了矿井采煤工作面顶板事故防治的重要性,通过对事故成因的分析,提出了相应的防治策略,通过对比,证实了研究方向的准确性,可以为矿山安全生产提供有益的参考。

双厚组合坚硬顶板定向长钻水力压裂评价体系研究

针对双厚组合坚硬顶板厚煤层工作面开采过程中的强矿压显现问题,本文提出了定向长钻水力压裂方案,并基于压力实测、瞬变电磁及钻孔窥视方法从孔内、孔外、动态、静态四个方面对定向长钻水力压裂裂缝扩展进行可视化监测评价。研究成果表明:压裂过程包括钻孔周围微裂隙发育扩展,出现宏观裂缝,宏观裂缝周围微裂隙发育,出现新的宏观裂缝,直至压裂完成;钻孔径向20m范围内岩层电阻率较低,大裂缝较为发育;设计的3个钻孔压裂后影响范围基本可以覆盖整个顶板治理区域;长钻孔内各压裂段裂隙可以实现贯通,钻孔内纵裂隙、横裂隙交替发育形成三维裂隙网络;压裂后顶板微震事件总能量和总次数都显著降低,压裂层位顶板能量提前释放,表现为“高频低能”显现,工作面来压强度明显改善。

托顶煤切顶留巷围岩控制技术研究

为了解决托顶煤巷道围岩变形难以控制的问题,运用理论分析、离散元数值模拟及现场工业试验相结合的方法对义棠煤业100602工作面切顶成巷围岩控制技术进行研究,分析了不同切顶高度、采高对留巷围岩变形影响规律。研究发现,适当增加切顶高度并降低采高有利于巷道围岩稳定,并确定开采技术参数为切顶高度24 m、采高6 m。现场监测结果显示,在合理的支护策略及开采工艺参数下,托顶煤切顶留巷围岩变形控制效果良好。

丙烯酰胺改性粉煤灰聚合增韧注浆材料研究

煤矿采煤工作面顶板烧变岩涌(失)水高效治理需要具有压缩韧性优良的注浆加固材料。硅酸盐水泥基注浆材料成本低,已在煤矿注浆加固中广泛应用,但存在硬化浆体变形韧性较差的问题。采用丙烯酰胺(AM)原位聚合增韧的方法,研究丙烯酰胺、交联剂、引发剂的掺量和水灰比对粉煤灰基注浆材料的凝结时间、溶胀性、抗压强度、韧性指数的影响,并采用SEM观测硬化浆体的微观结构。结果表明,丙烯酰胺可以在粉煤灰浆液中原位聚合生成聚丙烯酰胺(PAM)凝胶;当AM掺量为25.0%,交联剂掺量为0.75%,引发剂掺量为2.25%,水灰比为0.575时,材料抗压变形率大于60%,溶胀比达到113.43,韧性指数达到257.92%;通过SEM观测发现,注浆材料硬化浆体形成以粉煤灰颗粒为刚性骨架、聚丙烯酰胺凝胶为柔性网络的无机有机镶嵌网络结构,硬化浆体的压缩应力-应变曲线的变形率普遍大于40%,具有显著的塑性变形特征;工程实验结果显示最大抗折韧性变形率可达到25.86%。该注浆材料具有优异的韧性、流动性及较好的遇水膨胀性,可用于煤矿顶板渗漏水治理。

非均匀顶板岩层对覆岩破坏的控制作用模拟研究

松散含水层下采动顶板覆岩破坏问题受到广泛关注,但现有数值模拟成果普遍将顶板覆岩简化为均匀层状结构,不能反映出不同岩性的岩层分布对覆岩破坏的控制作用,具有一定的局限性。以孙疃矿101采区1010工作面为例。首先依据相关资料基于GOCAD软件建立精确三维地质模型,其次通过转换接口将模型导入FLAC^(3D)软件中模拟采动,分析顶板非均匀岩层对覆岩破坏的控制作用。结果表明:非均匀顶板煤岩层及四含松散层对覆岩破坏具有一定控制作用;软弱岩层越厚,塑性区最大高度越高,发育速度越快,反之高度越低,速度越慢;塑性区发育至软弱煤岩层时,高度增长明显。而发育至坚硬煤岩层时,高度增长较小甚至不增长;四含松散层厚度越大,塑性区最大高度越高,发育越快,反之最大高度越小,发育越慢。

近距离坚硬顶板巷道水力控顶理论及其应用研究

为研究近距离坚硬顶板巷道水力控顶理论,通过理论分析和数值模拟研究了水力化控顶卸压时煤层载荷、巷道应力分布规律,揭示了水力化控顶卸压对巷道围岩稳定性的影响机制,阐明了该技术的工艺流程。研究结果表明:81403回风巷道未开掘时,工作面周期来压步距19 m,直接顶厚度4.84 m,基本顶厚度10.64 m,内应力区范围5.2 m;远离81401采空区侧的15#煤层荷载与巷道开掘和单向切顶后相比分别降低了20%、15%;现场观测切顶钻孔试验区域巷道高度收敛率为33.7%、巷道宽度收敛率为23.0%,巷道高度收敛率较对比区域降低39%、宽度收敛率较对比区域降低32%。采用单侧高压磨料射流钻孔切顶能使顶板岩层及时垮落,切断顶板岩层间应力传递途径,能有效改善巷道围岩应力状态,减少工作面回采巷道后期顶底板及两帮变形量,降低巷道维护难度。

大巷煤柱回收工作面顶板控制技术研究

针对轿子山煤矿9717大巷煤柱回收综采工作面实际生产情况,综合运用现场监测、数值模拟和理论分析手段,开展大巷煤柱回收孤岛工作面矿压显现规律及控制方法研究,进行工作面预裂爆破强制放顶参数设计,并在该工作面进行工程应用,对回采期间顶板及工作面超前段回采巷道进行矿压监测,分析工作面矿压显现特征,达到保障工作面安全生产目标。研究成果将对类似地质条件下的煤柱回收工作面的回采具有一定的借鉴意义。

超长大采高回撤通道破坏特征及主被动协同控制技术

针对超长大采高工作面预掘回撤通道大变形失稳导致巷道破坏、设备回撤受阻等安全问题,采用理论分析、数值模拟、现场试验等方法,基于回撤通道破坏特征分析,提出“控顶固帮”主被动协同控制技术。建立了超长工作面采动支撑压力顶帮联合失稳力学模型,基于超长大采高顶板断裂位置与围岩稳定关系,揭示回撤通道破坏机理。利用UDEC数值模拟对超长大采高回撤通道区域环境进行验证,提出了“实时断顶+垛式支架+锚杆索”协同控制方案,保障回撤通道稳定。该技术在黄玉川煤矿226_(上)03综采工作面回撤通道成功应用,监测结果表明:工作面贯通后,回撤通道顶板下沉量为75.6 mm,底板鼓出量95.7 mm,两帮变形量103 mm,变形量小、支护效率高、成本低,实现了黄玉川煤矿超长大采高工作面回撤通道稳定安全高效的目的。

浅谈煤矿采煤工作面顶板控制措施

主要探讨了煤矿采煤工作面顶板控制措施。通过分析顶板控制对采煤工作面稳定性的影响、对确保采煤工作面安全和生产效率的重要性,以及顶板控制失效的情况,提出了一系列有效的顶板控制措施,包括选择支护方式、实施预防性支护和建立灾害监测预警系统。研究对煤矿采煤工作面的顶板控制具有重要的理论意义和实际应用价值。

缓倾斜中厚矿体采矿方法研究

该文以国外某缓倾斜中厚铅锌矿体赋存条件及开采技术问题为背景,提出一种高效的垂直分条嗣后充填采矿法,并对该采矿法成功应用存在的技术问题进行分析。针对矿体上盘围岩条件差、下盘三角矿体回收困难,提出双进路出矿巷道2步骤回采控顶技术和预控顶垂直分条嗣后充填采矿法2种解决技术方案,以争取实现此类缓倾斜中厚矿体的安全高效开采。