中深孔房柱法工业试验与工艺特征

房柱法是缓倾斜中厚以下矿体主要开采方法之一，在我国金属矿山普遍采用，且多为浅孔落孔。为克服常规浅孔房柱法采切比大，采准时间长，矿石损失率高的不足，设计改变其浅孔落矿方式为预切顶中深孔落矿，通过３个采场的试验，较好地解决了上述问题，并对新的采矿方法进行了分析评价。     

复杂残矿资源中深孔爆破协同落矿采矿工艺

针对高峰矿-200～-189 m水平下盘矿体的复杂开采技术条件,基于协同开采理念,设计上、下向扇形中深孔协同利用崩矿空间落矿嗣后充填采矿的回采方案。工业试验表明,与浅孔留矿嗣后充填采矿法相比,上、下向扇形中深孔协同利用崩矿空间落矿嗣后充填采矿法的矿房生产能力由195 t/d提高到420 t/d,贫化率由10%降低至5%,实现了高峰矿的安全高效回采,可为其他矿山类似的残矿资源回收提供参考。     

采动影响下断层活化规律的数值模拟研究

以采用库仑剪切模型的接触面单元代表断层两盘的接触状态,模拟工作面从断层上盘和下盘向断层方向逐步回采的过程,研究断层接触面上法向应力和剪切应力的时空演化规律、断层上下盘的运动规律.模拟发现:在工作面回采的过程中,断层带上的应力分布具有明显的时空特征,断层上法向应力和剪切应力对采动影响具有不同的敏感性,断层法向应力的变化总是早于剪切应力;工作面距离断层越近,断层越易于活化,上盘推进时,断层影响范围约为断层前方60m,下盘推进时,工作面与断层距离小于20m时断层最易出现活化;不同的回采方式会引起断层不同的活化危险性,相比上盘开采,下盘开采时采动对断层的影响范围更为集中,活化危险性更高.     

利用超声波传播速度估计岩体应力状态的可能性

一、前言在东川矿务局因民矿面山坑急倾斜矿体连续空场采矿法试验中,由于不留间柱,矿体上盘围岩完全依靠顶柱和底柱支撑。因此,该采矿法成败的关键,在一定程度上将取决于顶柱的稳定性。为了掌握回采过程中顶柱及上、下盘围岩的应力状态及其随上盘暴露面积增大而变化的趋势,以便为采场地压控制提供依据,该矿决定用超声波等手段进     

复合顶板无煤柱自成巷切顶爆破设计关键参数研究

为对无煤柱自成巷切顶爆破关键参数设计方法进行总结和优化,运用几何推演、数值模拟、力学分析、现场试验等手段,提出复合顶板无煤柱自成巷切顶爆破设计的系统化流程及方法,并归纳为切顶设计与爆破设计2类,包含切顶高度、切顶角度、切顶连通率与单孔装药量、炮眼间距、单次起爆数量共计6个关键参数.随后以塔山煤矿8304工作面留巷顺槽Ⅰ区复合顶板为例,设计得到其切顶爆破关键参数:切顶高度为8m,切顶角度为15°,顶板切缝连通率至少应达到82%,单孔采用的装药结构为43331,炮眼间距为500mm,单次起爆炮孔数量为6个.现场应用验证切缝成巷效果良好,切缝侧周期来压步距平均增大4m,液压支架平均来压强度降低2.1MPa,峰值来压强度降低10.2MPa,预裂卸压效果较为明显.     

木城涧煤矿异常条件下回采底分层空间模拟试验研究

通过对北京矿务局木城涧煤矿不具备常规条件下十槽煤底分层的相似材料模拟试验研究,证明了回采上分层时顶板冒落情况和矿压显现规律,初步探明了留与不留煤皮假顶情况下,回采下分层时顶板岩层二次失稳情况和矿压显现规律,为类似条件下开采底分层制定合理的回采方案、安全技术措施等提供重要的依据.     

切顶卸压沿空留巷爆破孔关键参数选择及留巷效果 现状分析

切顶卸压沿空留巷技术是一种主动预裂卸压的无煤柱留巷技术,相对于传统的巷旁充填沿空留巷技术而言,它具有性价比高、工艺简单、留巷速度快等优点,因此,近年来得到了快速发展。总结了中国30多个代表性矿区切顶卸压沿空留巷技术的应用现状,并对其定向爆破孔的关键参数,如切顶高度、切顶角度、切顶钻孔间距以及切顶钻孔直径等选择范围进行了统计,也对留巷效果进行了分析。结果表明,目前切顶卸压沿空留巷技术主要应用于0.9～3.5 m厚的薄煤层以及中厚煤层,切顶高度为1.8～20 m,切顶角度为0°～20°,切顶钻孔间距为200～2 000 mm,切顶钻孔直径为32～80 mm,留巷动压影响范围为20～280 m。总结了目前切顶卸压沿空留巷成功应用的经验,分析了存在的一些问题,对于推广切顶卸压沿空留巷技术具有重要的工程参考价值。     

木城涧煤矿异常条件下回采底分层空间模拟试验研究

通过对北京矿务局木城涧煤矿不具备常规条件下十槽煤底分层的相似材料模拟试验研究 ,证明了回采上分层时顶板冒落情况和矿压显现规律 ,初步探明了留与不留煤皮假顶情况下 ,回采下分层时顶板岩层二次失稳情况和矿压显现规律 ,为类似条件下开采底分层制定合理的回采方案、安全技术措施等提供重要的依据     

"锚杆护顶浅孔+中深孔留矿"法在 高井槽铁矿的应用

针对高井槽铁矿原采矿方法顶板维护难题,提出了锚杆护顶浅孔+中深孔留矿法采矿方案,将矿体分为两层,上层用浅孔爆破回采,下层用平行中深孔落矿,上、下两层同时自下而上推进,利用锚杆对局部不稳固顶板进行加固。该采矿方案在矿山进行了采矿实验并取得成功,相对原开采方案,新方案千吨采切比减少了2.42 m·kt~(-1),综合回收率提高了5.2%,采矿工效提高了2.3 t·工~(-1)·班~(-1),生产能力提升了120 t·d~(-1),大块率下降了4.3%,采矿直接成本下降了5.6元·t~(-1),该采矿方案具有较好的应用推广价值。     

突出煤层底抽巷位置优化研究

针对突出矿井底抽巷合理位置的布置问题,结合豫西某矿首采工作面地质条件,采用FLAC3D对8种回采巷道与底抽巷相对位置的设计方案进行数值模拟,对比分析各布置方式条件下巷道围岩应力分布规律及巷道变形特征,综合经济因素及现场操作情况确定最优设计方案。结果表明:回采巷道与底抽巷垂距为5.8 m、垂距为10 m平距分别为10 m和15 m的设计方案均能满足巷道稳定性和支护要求,但从经济效益方面考虑垂距平距均为10 m的设计方案最优;经实践验证,回采巷道与底抽巷垂距和平距均为10 m的设计方案顶底板和两帮移近量可满足安全生产要求,抽采后残存瓦斯含量控制在3.3~5.8 m3/t,防突效果明显。此设计方案的成功运用,不仅可以指导该煤矿的安全、高效生产,而且也可为具有类似地质条件矿井的底抽巷布置提供借鉴和参考。     

康家湾永久防水矿柱安全开采可行性

康家湾矿是典型的大型水体下矿床,开采技术条件极其复杂,而留设大量永久防水矿柱,造成资源积压．分析了矿区内主要构造对顶板围岩及含水层影响、顶板与隔水层和相对隔水层位置关系、含水层及勘探钻孔对矿柱回收的影响;计算了冒落带和导水裂隙高度及安全开采深度;用ANSYS有限元软件模拟了空区上覆岩层稳定性及最大允许暴露面积．结果表明,断层不会连通空区与水体,矿柱顶板围岩稳固,与含水层的隔水层和相对隔水层厚度在190m以上;充填未接顶高度应控制在2．0m内,采动后的安全厚度应大于65m;对空区及时、高质量充填有利于永久防水矿柱的回收;理论的采空区极限暴露面积可达3360—4000m^2．因此,在满足以上研究参数条件下,采用充填法对康家湾永久防水矿柱进行回收是完全可行的．     

深部沿空切顶成巷围岩稳定性控制对策

基于沿空切顶成巷技术原理,以城郊煤矿深部工作面无煤柱开采为背景,综合运用力学分析﹑模拟计算和现场试验等方法,对深部切顶成巷围岩控制关键对策进行深入研究。结果显示：切顶留巷顶板在侧向形成短臂梁结构,降低了巷旁支护体所受压力,切缝范围内岩层垮落后碎胀充填采空区,使留巷顶板下沉量降低了约50%。采空区侧顶板为切顶巷道围岩变形的关键部位,需进行加强支护;深部切顶巷道实体煤帮塑性区范围大,通过煤帮锚索支护技术可将浅部锚杆承载层锚固在弹性区稳定煤体中;深部切顶成巷来压速度快、强度大,巷内单体支柱易造成冲击破断,采用高阻力液压支架巷内临时支护时可较好地抵抗深部强动压;巷旁刚性挡矸装置因无法适应深部围岩大变形而受压弯曲破坏,深部切顶巷道巷旁挡矸结构需实现一定的竖向让位卸压方可与顶底板协调变形。在研究的基础上提出恒阻锚索关键部位支护+可缩性U型钢柔性让位挡矸+巷内液压支架临时支护+实体煤帮锚索补强的深部切顶成巷联合支护技术,并进行现场工业性试验。现场监测结果表明：留巷围岩在滞后工作面约290 m时基本稳定,且稳定后各项指标满足下一工作面使用要求。     

Domino instability effect of surrounding rock-coal pillars in a room-and-pillar gob

To discuss the domino instability effect and large area roof falling and roof accidents of surrounding rock-coal pillars in a room-and-pillar gob, the equilibrium equation for a roof-coal pillar-floor system with the influence of mining floor was developed based on the engineering conditions of the surrounding rock in a room-and-pillar gob in the 3^?2 coal seam of Tanggonggou mine. The conditions of system instability and the relationship between system stability and system stiffness were analyzed from an energetic point of view. Numerical simulation using the discrete element software UDEC was also carried out to simulate conditions causing the domino effect on surrounding rock-coal pillars in a 3^?2 room-and-pillar gob. The results show that: if we want the system to destabilize, the collective energy in roof-and-floor must be larger than that in the coal pillar. When the stiffness of the coal pillars and the roof-and-floor are both greater than zero, the system is stable. When the stiffness of the coal pillars is negative but the summed stiffness of the coal pillars and roof-and-floor is larger than or equal to zero, the system is statically destroyed. When the sum of the coal pillars and the roof-floor stiffness is negative, the system suffers from severe damages. For equal advance distances of the coal mining face, the wider coal pillars can reduce the probability of domino type instability. Conversely, the smaller width pillars can increase the instability probability. Domino type instability of surrounding rock-coal pillars is predicted to be unlikely when the width of coal pillars is not less than 8 m.     

Analysis of factors and countermeasures of mining subsidence in Kaiyang Phosphorus Mine

1 INTRODUCTION After useful mineral body has been mined and dragged out, mining goaf is formed and country rocks would probably lose original equivalence. When span of the goaf is long enough, even if the roof is hard and intact, the rock around the goaf would move towards the mining openings, and this movement would pass on to the adjoining rock mass until it reaches the surface and ground displacement can be observed. In other words, underground mining may cause ground cracks and surface…     

Similar material simulation of time series system for induced caving of roof in continuous mining under backfill

With the help of similar material simulation test,time series system for induced caving of roof in continuous mining under complex backfill in ore body No.92 of Tongkeng Tin Mine was studied. According to the similarity theory,a two-dimensional similar simulation test-bed was constructed. The stress and displacement that change along with the advance of mining were acquired and analyzed automatically by data system. The processes of continuous mining of ore-block in 5 intervals and artificial induced caving of roof were simulated. The results of the test show that ore body remained as safety roof in thickness of 15 m guarantees the safe advance of stoping work face. Caving of safety roof puts in practice at the first two mining intervals when the third interval of continuous mining is finished,and one interval as the safety distance should be kept all the time between stopping and caving. While mining in the last interval,pre-slotting should be implemented first of all,and the roof of the last two mining intervals is caved simultaneously. Only this kind of time series system can be an efficient and safe way for induced caving of roof in continuous mining.     

Numerical analysis of application for induction caving roof

New method for handling roof of the base successive mining is proposed, which is induction caving in the roof. The key is that it is made certain to the station of the space-time in the induction caving roof, as the stress is released with the mining process. And applying the catastrophe theory, the influencing factors of induction caving roof are studied in the emptied areas, such as the mechanical property of the surrounding rock, the area of the gob,the scope and dimension of tensile stress. The results show that the key factor is the area of the gob to the method of the induction caving roof. Then according to the geology and the ore characteristic, the three dimension FEM mechanical model is built in Tongkeng Mine, the laws of the tensile stress are analyzed to the space and the time in the roof with the mining, then it is rational design to the mine step and time of the handing the roof.     

潼关金矿505~＃矿体采矿方法研究

陕西潼关金矿５０５＃矿体，采用锚杆预控顶爆力运搬采矿法开采，获得成功。本文对应用价值工程优选采矿方法、锚杆预控顶技术、爆力运搬技术、中深孔浅孔一次爆破拉切割立槽等进行简明扼要地论述。     

Mechanisms of support failure and prevention measures under double-layer room mining gobs – A case study: Shigetai coal mine

In the practice of mining shallow buried ultra-close seams, support failure tends to occur during the process of longwall undermining beneath two layers of room mining goaf (TLRMG). In this paper, the factors causing support failure are summarized into geology and mining technology. Combining column lithology and composite beam theory, the key stratum of the rock strata is determined. A finite element numerical simulation is used to analyze the overlying load distribution rule of the main roof for different plane positions of the upper and lower room mining pillars. The tributary area theory (TAT) is adopted to analyze the vertical load distribution of each pillar, and dynamic models of coal pillar instability and main roof fracture are established. Through key block instability analysis, two critical moments are established, of which critical moment A has the greater dynamic load strength. Great economic losses and safety hazards are created by the dynamic load of the fracturing of the main roof. To reduce these negative effects, a method of pulling out supports is developed and two alternative measures for support failure prevention are proposed: reinforcing stope supports in conjunction with reducing mining height, or drilling ground holes to pre-split the main roof. Based on a comprehensive consideration of economic factors and the two categories of support failure causes, the method of reinforcing stope supports while reducing mining height was selected for use on the mining site.     

Numerical analysis of application for induction caving roof

New method for handling roof of the base successive mining is proposed, which is induction caving in the roof. The key is that it is made certain to the station of the space-time in the induction caving roof, as the stress is released with the mining process. And applying the catastrophe theory, the influencing factors of induction caving roof are studied in the emptied areas, such as the mechanical property of the surrounding rock, the area of the gob, the scope and dimension of tensile stress. The results show that the key factor is the area of the gob to the method of the induction caving roof. Then according to the geology and the ore characteristic, the three dimension FEM mechanical model is built in Tongkeng Mine, the laws of the tensile stress are analyzed to the space and the time in the roof with the mining, then it is rational design to the mine step and time of the handing the roof. Foundation item: Project(50490274) supported by the National Nature Science Foundation of China     

A coal rib monitoring study in a room-and-pillar retreat mine

The National Institute for Occupational Safety and Health(NIOSH) conducted a comprehensive monitoring program in a room-and-pillar mine located in Southern Virginia. The deformation and the stress change in an instrumented pillar were monitored during the progress of pillar retreat mining at two sites of different geological conditions and depths of cover. The main objectives of the monitoring program were to better understand the stress transfer and load shedding on coal pillars and to quantify the rib deformation due to pillar retreat mining; and to examine the effect of rib geology and overburden depth on coal rib performance. The instrumentation at both sites included pull-out tests to measure the anchorage capacity of rib bolts, load cells mounted on rib bolts to monitor the induced loads in the bolts, borehole pressure cells(BPCs) installed at various depths in the study pillar to measure the change in vertical pressure within the pillar, and roof and rib extensometers installed to quantify the vertical displacement of the roof and the horizontal displacement of the rib that would occur during the retreat mining process.The outcome from the monitoring program provides insight into coal pillar rib support optimization at various depths and geological conditions. Also, this study contributes to the NIOSH rib support database in U.S coal mines and provides essential data for rib support design.