综采放顶煤采煤工作面深部开采发生事故时岩爆危险性分析外文文献翻译

Analysis on rock burst danger when fully-mechanized caving coal face passed faultwith deep miningChen Xuehua a, Li Weiqing b, Yan Xianyang baCollege of Resources and Environment Engineering, Liaoning Technical University, Fuxin, ChinabDongtan coal Mine, Yanzhou Coal Mining Company Limited, Zoucheng, ChinaAbstractWhen fully-mechanized caving face passed fault, rock burst accidence easily occurred. The SOS microseismmonitoring system was applied to monitor the microseismic activities all time occurred in the coaland rock mass near the fault area. Variation features of microseismic energy releasing and microseismicfrequency were analyzed. Numerical simulation method was used to research the abutment stress distributionwhen coal face passed fault, which was compared with microseism occurrence rules. When thecoal face approached to fault, the abutment stress increases gradually, so the high stress would accumulatenear the fault region. When the coal face left fault, the abutment stress decreased. The SOS microseismmonitoring results showed that microseismic activity in the fault area had a high instability.When the coal face neared to the fault, total energy value and frequency released by the microseism steadilyincreased. The maximum energy peak value also had the tendency to rapidly increase. Before thestrong shock occurred, there was a period of weak seismic activity. The weak seismic activity showedenergy accumulation for strong shock, which can be used to forecast the danger of rock burst.Keywords:Rock burst;Microseism monitoring system;Fault;Numerical simulation1.IntroductionThe equipment will be damaged, and people will be injuredwhen rock burst occurs, which is one of the biggest disasters tomine safety. With the expansion of mining and tunneling, the conditionof mining face will be complex, the mining activity in thecoal pillar and adjacent to coal pillar is inescapability. During themining progress in deep coal seam, influenced by the fault structure,the mine pressure appears very violently around the excavationface, the sound of mine quake becomes larger, and the numberof mine quake becomes more and more. Research on the rock burstoccurrence rule under the complex geological structure is verynecessary to safety production.The domestic and oversea scholars (Su and Li, 2008; Lu et al.,2008; Li et al., 2008a,b,c; Lu et al., 2007; Gou et al., 2007; Jianget al., 2006; Dou and He, 2004; Song et al., 2004; Caim Kaiserand Martin, 2001; Meng et al., 2001; Huang and Gao, 2001; Panet al., 1998) have studied the mechanism of fault activity inducingrock burst, and the microseismic law of rock burst portent. Theslide destabilization characteristic of surrounding rock, the stressdistribution and change rules, and rock burst occurrence mechanismwere researched by the viewpoint of the fault upper walland lower wall, coal seam roof and floor, and fault fractured zoneand coal mechanics character in the relevant document. The researchon rock burst danger of fully-mechanized caving coal facepassed fault is relevantly less.The No. 14310 coal face passing the No. NF6 fault in the Dongtanmine was acted as research object. The relevant mathematicalmodel was used to research the rock burst mechanism induced bythe activity of regional surrounding rock. Microseismic law of coalface passed fault was explored, which can guide the forecast andprevention of rock burst.2.Microseismic activity monitoring and change rules in faultregion when coal face excavated2.1. Change rules of microseismic hypocenterThe Polish SOS microseismic monitoring system was used in theDongtan mine, and the microseismic activity was monitored andlocated in real time. The change of microseismic hypocenter positionand energy was recorded when the coal face passed the No.NF6 fault. The monitoring result about concentrative and violentdistribution of microseismic hypocenter was analyzed.Illustrated as Fig. 1, all kinds of the points showed microseismichypocenter position, the different shapes showed different microseismicgrades, and the black short line showed the excavationposition of coal face. According to the monitoring result, the microseismichypocenter changed along with the excavation progress. Inthe vertical section, the hypocenter changed obviously. When thecoal face was far from the fault, the excavation was little influenceon fault activity, and the microseismic hypocenter mainly distributedin the front of coal face and on the goaf.In July 26, 2010, the distance of coal face far from fault was62 m, the mine pressure emergence near coal face enhanced, thetimes of microseismic occurrence increased obviously, but themicroseismic grade was small. At this time, microseismic beganto appear near fault, which showed the fault activity was influencedby the coal face excavation (see Fig. 1a).Fig. 1. Distribution change of microseismic hypocenter along with coal face excavation in vertical section.Along with coal face excavation, microseismic activity wasmore and more obvious, hypocenter point concentrated on thehard rock seams above the main roof and near the fault (seeFig. 1c and d). In August 25, 2010, the distance that coal face leftfault was 80 m, microseismic occurrence was not influenced byfault, microseismic times reduced, microseismic position still beganto distribute in the front and goaf of coal face. According tothe microseismic monitoring result, there was rock burst dangerin the region near the fault under the excavation disturbance.2.2. Changes of microseismic total energy and microseismic timesAccording to the excavation progress, changes of microseismictotal energy and microseismic times were drawn as Fig. 2 duringthe period of coal face passing the fault.Since July 25, when the distance of coal face far from fault wasabove 60 m, microseismic times obviously increased. But microseismictotal energy little changed, and microseismic grade wasmainly small. After August 5, 6, high energy microseismic beganto appear, energy changed violently, which presented two rules:Firstly, microseismic energy undulated on a special level, but theamplitude difference between maximum energy and minimum energywas big. Secondly, before strong shock occurred, the frequencyand grade of microseismic activity had the decreasetendency. After strong shock occurred, microseismic usuallyturned to low energy shock. So the low energy shock showed thetendency of energy accumulation for strong shock occurrence.After August 24, the changes of microseismic energy were notinfluenced by the fault structure.(a) Changes of microseismic total energy (b) Changes of microseismic timesFig. 2. Changes histogram of microseismic energy and times during the coal face passing fault.3.Mine pressure emergency near the fault under the influenceof excavation3.1. Numerical simulation modelThe mining depth was above 600 m, so the uniformly distributionload acted on the upper boundary of model was 12.86 Mpa(Zhu et al., 2007). X direct displacement of model left and rightwas 0, and X direct displacement and Y displacement of model bottomwas 0 (see Fig. 3). Material constitutive relation was MohrCoulomb. The rock seam properties (see Table 1) referred to theNo. 49 geological borehole of the No. 14310 coal face in Dongtanmine. The fault mechanics property was referred to the relevantdocument (Zhou et al., 2006; Wang et al., 2003; Li et al., 2008a,b, c).Fig. 3. Numerical simulation model.3.2. Fault influence on abutment stressThe coal face excavated from fault lower wall to fault upperwall, when the different distance between coal face and faultrespectively were 80 m, 65 m, 40 m, 20 m, _5m, _30 m, _70 m,_100 m, the different abutment stresses distribution was illustratedas Fig. 4, and the peak value of different abutment stresseswas listed in Table 2.Table 1Rock seam properties of model.Table 2Peak value of abutment stress.When the distance between coal face and fault was 80 m and65 m, the two curve of abutment stress ahead of coal face werebasically superposition, so fault influence on abutment stress wasvery small. Numerical simulation results showed that in the coalbody ahead of coal face, stress peak value reached to 53.37 MPa,stress concentration factor reached to 3.42, the distance of stresspeak value far from coal wall of coal face was 24.2 m, and the stressinfluence scope was above 50 m. On-situ observation results indicatedthat the distance of stress peak value far from coal wall ofcoal face was more than 23.5 times of excavation coal height,the stress influence scope was 4060 m, and stress concentrationfactor was 2.53 (Qian and Shi, 2003). The above two researchresults were similar, which explained that numerical simulationmodel was reasonable.Fig. 4. Distribution of abutment stress.Along with the coal face approached to fault, the fault influenceon abutment stress enhanced, and the stress peak value graduallyincreased. When the distance between coal face and fault was40 m, stress peak value reached to 70.84 MPa, stress concentrationfactor reached to 4.54, the distance of stress peak value far fromcoal wall of coal face was 25.2 m. When the distance between coalface and fault was 20 m, stress peak value rapidly reached to90.21 MPa, stress concentration factor reached to 5.78, the distanceof stress peak value far from coal wall of coal face was20.12 m. After the coal face left fault, the stress in the coal bodygradually decreased, for example, the distance of coal face left faultwas 30 m, stress peak value decreased to 74.81 MPa, and when thedistance was 50 m, peak value was 52.03 MPa, which was similarto normal excavation.Fig. 5 illustrated distribution nephogram of abutment stresswhen there were different distances between coal face and fault.When the distance of coal face approached fault was 15 m, therewas obviously stress concentration (see Fig. 5a) near the fault.When the distance of coal face left fault was 20 m (see Fig. 5c), rockseams near the fault were mostly destroyed, so the stress was little.Fig. 5. Distribution nephogram of abutment stress with different distances between coal face and fault.4.Conclusions(1) When the fully-mechanized caving coal face with deep miningand big excavation height passed fault, several strongshocks occurred, which indicated that the great scope of rockand coal seams fractured and destroyed under the action ofabutment stress and fault tectonic stress, there was rockburst danger near the fault region.(2) Microseismic activity had obviously rule. When the coal faceexcavated normally, microseismic energy undulated on aspecial level. On the special conditions, before strong shockoccurred, the frequency and grade of microseismic activityhad the decrease tendency. After strong shock occurred,microseismic usually turned to low energy shock. So thelow energy shock showed the tendency of energy accumulationfor strong shock occurrence.(3) When coal face approached to fault, the abutment stress onthe front of coal face obviously increased, so the rock burstdanger near the fault was bigger.(4) Under the influence of coal face excavation, fault had thepossibility of instability and slippage, which was becausein the fault region, microseismic intensity obviouslyincreased, and most of microseismics occurred in the roofof coal seam. These rules can be used to forecast rock burstdanger.综采放顶煤采煤工作面深部开采发生事故时岩爆危险性分析Chen Xuehua a, Li Weiqing b, Yan Xianyang ba 资源与环境工程学院，辽宁工程技术大学，阜新，中国b东滩煤矿，兖州煤业股份有限公司，山东邹城，中国摘要综放工作面采煤通过断层时，容易出现岩爆事故。 SOS微震监测系统用于监视所有的时间在煤岩体和断层附近地区发生的微震活动，对微震能量释放和微震频率的变化特征进行了分析。数值模拟方法被用来研究当采煤工作面支承压力分布通过故障时的模拟数据，这是与微震的发生规律相比较。当工作面将要发生事故，支承压力逐渐增大，因此，此时高应力会积累断层附近地区。当采煤工作面经过断层，支承压力下降。 SOS微震监测结果表明，在故障区的微震活动有一个高的不稳定阶段。当工作面接近断层，微震释放的总能量值和频率不断增加，支架支撑强度的最大能量峰值也有迅速增加的趋势。强烈的冲击发生之前，有一个微弱的地震活动期。弱地震活动表现出强烈的冲击能量积累，它可以用来预测岩爆的危险。关键词：岩爆，微震监测系统;故障;数值模拟1 介绍岩爆发生时，采煤设备将被破坏，工作人员容易受到伤害，这是煤矿安全的最大的灾害之一。采矿和隧道的逐步扩大，采煤工作面的条件将是复杂的，在煤柱附近的采矿活动是不可避免的。在深部煤层断裂构造的影响，开采进度，矿山压力出现非常猛烈的开挖面周围，矿震的声音变得更大，矿震的数量越来越多。复杂的地质结构下的岩爆的发生规律的研究对于安全生产是非常必要的。国内和海外的学者研究了断层活动诱发岩石的机制爆裂，叫做岩爆前兆微震法。围岩的应力分布和变化规律，从而对岩爆的发生机制的不稳定的特点进行了研究，由于断层高度较低，由煤层顶板和地板的角度来看，就断层破碎带和煤力学性质有关文件，研究岩爆通过综放采煤工作面相关的相关。充当研究对象的第14310号NF6故障在东滩煤矿的采煤工作面传递。相关的数学模型，用于研究区域围岩活动诱发的岩爆机制。通过对采煤工作面的微震事故进行探讨，可以引导岩爆预测和预防。2 工作面采煤时微震活动的监测和故障区域的变化规律2.1微震震源变化规律波兰SOS微震监测系统在东滩矿进行对采煤工作面通过No.NF6时记录的微震震源位置、能量的变化和微震活动的实时监测。对微震震源分布集中和爆力有关的监测结果进行了分析。如图1，各点显示微震震源位置，不同形状的具有不同微震成绩，短黑线表明开挖工作面的位置。根据监测结果，微震震源改变沿开挖进度。在垂直剖面，震源发生了明显变化。当工作面从断层远，开挖断层活动的影响不大，微震震源主要分布在前面的采煤工作面和采空区。2010年7月26日，采煤工作面故障的距离是在62米，增强附近采煤工作面矿山压力出现，微震发生的时间明显增加，但微震等级小。在这个时候，的微震开始出现断层附近，这表明断层活动是由采煤工作面开挖的影响（参见图1a）。随着采煤工作面开挖，微震活动是越来越明显，震源集中点以上的主要断层附近的屋顶和坚硬的岩石缝（见图1C和D）。在2010年8月25日，采煤工作面故障是80米的距离，发生微震没有故障的影响，减少微震倍的，微震位置仍然在前面和采煤工作面采空区开始分发。据微震监测结果，预测和防治有断层附近地区开挖扰动下岩爆的危险。2.2变化的微震总能量和微震倍根据开挖进度，微震的总能量和微震时代的变化绘制成图2。在采煤工作面，通过故障期间。自7月25日，采煤工作面的距离远从故障是在60米以上时，微震次数明显增加。但微震的总能量变化不大，微震等级，主要是小。之后，8月5、6日，高能量微震开始出现，能源剧烈变化，这提出了两个原则：首先，微震能量一个特殊的水平上波动，但之间的最大能量和最小能量的幅度差异大。其次，强烈的冲击发生之前，微震活动的频率和档次有下降的趋势。强震发