采空区顶板冒落数值模拟模型边界尺寸确定及冒落规律

结合赵庄煤矿综采工作面顶底板岩层性质,在通用离散元软件UDEC中建立物理模型,对比了不同上边界、侧向边界尺寸模型数值模拟结果中老顶的下沉量,确定了为消除边界效应所需的模型边界.结果显示,模型上边界尺寸大于70 m,侧向边界尺寸大于100 m时,才能得到可靠的模拟结果.得到了不同工作面推进距离条件下的老顶冒落下沉规律,当推进距离大于300 m后,老顶沿推进方向在采空区中部最大下沉量不变;从采空区边界处开始随向采空区内部深入中粒砂岩下沉量逐渐增加,在距离采空区边界100 m左右增加至最大值2.70 m;随着距工作面距离增加,老顶中粒砂岩下沉量呈线性增加,在工作面后方120 m位置处下沉量达最大值2.70 m.     

Measurement of overburden failure zones in close-multiple coal seams mining

In the Kaiping Coal field, mining of five coal seams, located within 80 m in the Kailuan Group, #5, #7, #8,#9 and #12 coal seam, is difficult due to small interburden thickness, concentrated stress distributions,high coal seam metamorphism, and complex geological conditions. By using the ZTR12 geological penetration radar(GPR) survey combined with borehole observations, the overburden caving due to mining of the five coals seams was measured. The development characteristics of full-cover rock fractures after mining were obtained from the GPR scan, which provides a measurement basis for the control of rock strata in close multiple coal seam mining. For the first time, it was found that the overburden caving pattern shows a periodic triangular caved characteristic. Furthermore, it is proposed that an upright triangular collapsed pile masonry and an inverted triangular with larger fragments piled up alternately appear in the lower gob. The research results show that the roof structure formed in the gob area can support the key overlying strata, which is beneficial to ensure the integrity and stability of the upper coal seams in multiple-seam mining of close coal seams.     

Side abutment pressure distribution by field measurement

Given the 7123 working face in the Qidong Coal Mine of the Wanbei Mining Group, nine dynamic roof monitors were installed in the crossheading to measure the amount and velocity of roof convergence in different positions and at different times and three steel bored stress sensors were installed in the return airway to measure rock stress at depth. On the basis of this arrangement, the rule of change of the distribution of the side abutment pressure with the advance of the working face and movement of overlying strata was studied. The rule of change and the stability of rock stress at depth were measured. Secondly, the affected area and stability time of the side abutment pressure were also studied. The results show that: 1) During working, the face advanced distance was from 157 m to 99 m, the process was not effected by mining induced pressure. When the distance was 82 m, the position of peak stress was 5 m away from the coal wall. When the distance was 37 m, the position of peak stress away from the coal wall was about 15 m to 20 m and finally reached a steady state; 2) the time and the range of the peak of side rock pressure obtained from stress sensors were consistent with the results from the dynamic roof monitors; 3) the position of the peak pressure was 25 m away from the coal wall.     

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.     

Criterion of local energy release rate of gob instability in deep mines considering unloading stress path

The stress path characteristics of surrounding rock in the formation of gob were analyzed and the unloading was solved. Taking Chengchao Iron Mine as the engineering background, the model for analyzing the instability of deep gob was established based on the mechanism of stress relief in deep mining.The energy evolution law was analyzed by introducing the local energy release rate index(LERR), and the energy criterion of the instability of surrounding rock was established based on the cusp catastrophe theory. The results show that the evolution equation of the local energy release of the surrounding rock is a quartic function with one unknown and the release rate increases gradually during the mining process.The calculation results show that the gob is stable. The LERR per unit volume of the bottom structure is relatively smaller which means that the stability is better. The LERR distribution showed that there was main energy release in the horizontal direction and energy concentration in the vertical direction which meets the characteristics of deep mining. In summary, this model could effectively calculate the stability of surrounding rock in the formation of gob. The LERR could reflect the dynamic process of energy release,transfer and dissipation and that provided an important reference for the study of the stability of deep mined out area.     

晋城矿区9号煤沿空留巷试验研究

结合具体条件进行了巷旁充填支护参数设计 ,在矿压观测基础上 ,分析了留巷围岩变形及充填体载荷特征 ,把高水速凝充填材料沿空留巷与炮掘及综掘成巷方法进行经济对比 ,结果表明 ,该留巷方法有明显技术和经济优势 ,在晋城矿区 9号煤中有很好推广应用价值 .     

基于FLAC3D的深部隧道分区破裂特性研究

深部地层隧道施工期间,其围岩及支护构成一个复杂的承载体系。开挖导致深部岩体中出现的围岩分区破裂、岩爆等现象会给现场带来极大的安全隐患。围绕分区破裂化这一超常现象,依托淮南矿区某深部巷道工程,借助有限差分软件FLAC3D,通过模拟岩体高温、高地应力等特殊环境下,建立其响应模型,研究了原岩应力和内摩擦角对分区破裂化现象的影响。结果表明：不同原岩压力和内摩擦角对围岩分区破裂现象影响显著;当原岩压力在17.3~35.0 MPa内逐渐增大时,间隔破裂区域体积从0增大至25×102 m3;当摩擦角在22~38°区间内逐渐增大时,间隔破裂区域体积则从26.87×102 m3降至0,恢复至浅部隧道传统破坏模式。     

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.     

采空区残留矿柱回采研究

荡坪钨业有限公司宝山矿区475m中段采空区体积为20万m3,其中残留矿柱矿量8838 t.为安全有效回采残留矿柱,采用光弹性应力计、声发射等监测手段对采空区地压进行监测,监测结果分析表明,目前该采空区处于地压相对稳定期,根据上述研究结果并结合生产实际,确定了475m中段残留矿柱回采范围、回采方案,现场实践表明该方案是可行的,对类似矿山残留矿柱回采具有一定指导价值.     

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     

超长"孤岛"综放面大煤柱护巷的数值模拟

基于兖矿集团兴隆庄4324超长“孤岛”综放工作面开采条件，采用离散元数值计算程序UDEC3．0，模拟研究了不同宽度煤柱护巷条件下巷道围岩的应力分布和变形特征，分析了不同宽度煤柱的承载状况和应力峰值区的位置．研究表明，采用20m大煤柱维护巷道，可以改善巷道围岩应力环境；煤柱的承载能力适应超长“孤岛”综放工作面顶板的活动规律；围岩变形量小；能够保障巷道的整体稳定性和有效断面．通过现场实测，讨论了大煤柱维护巷道的矿压显现规律和对巷道的良好维护效果．     

Geotechnical considerations for concurrent pillar recovery in close-distance multiple seams

Room-and-pillar mining with pillar recovery has historically been associated with more than 25% of all ground fall fatalities in underground coal mines in the United States.The risk of ground falls during pillar recovery increases in multiple-seam mining conditions.The hazards associated with pillar recovery in multiple-seam mining include roof cutters, roof falls, rib rolls, coal outbursts, and floor heave.When pillar recovery is planned in multiple seams, it is critical to properly design the mining sequence and panel layout to minimize potential seam interaction.This paper addresses geotechnical considerations for concurrent pillar recovery in two coal seams with 21 m of interburden under about 305 m of depth of cover.The study finds that, for interburden thickness of 21 m, the multiple-seam mining influence zone in the lower seam is directly under the barrier pillar within about 30 m from the gob edge of the upper seam.The peak stress in the interburden transfers down at an angle of approximately 20°away from the gob, and the entries and crosscuts in the influence zone are subjected to elevated stress during development and retreat.The study also suggests that, for full pillar recovery in close-distance multiple-seam scenarios,it is optimal to superimpose the gobs in both seams, but it is not necessary to superimpose the pillars.If the entries and/or crosscuts in the lower seam are developed outside the gob line of the upper seam,additional roof and rib support needs to be considered to account for the elevated stress in the multiple-seam influence zone.     

Huge thick conglomerate movement induced by full thick longwall mining huge thick coal seam

A discrete elemental method was used to study the thickness of conglomerate layer in a full thick seam mining activities under the influence of the law, pointing out the thickness of the conglomerate at different seam mining, and during the destruction and instability of existing state of laws. At 21141 thick seam mining, the face toward the direction of separation between the thick layer of conglomerate rock and the next bit after reaching its maximum capacity due to pull from the bottom of the plastic zone, formed a stratified and hierarchical down collapse. The shape of caving area is a “triangular block”, the length of the plastic zone and face advancement from the linear fit between the height of the plastic zone and the advancing face is a quadratic function of distance, while the top layer of thick gravel layer is the overall bending subsidence trend. Tilting the direction of the face, a thick gob of collapsed conglomerate layer is formed in the coal gob entity on both sides of the thick conglomerate at the top of the overall fracture morphology performance, thus forming a mutual extrusion of articulated block structure. The instability, separation and balance of the thick conglomerate layer in the hinged block stope stress leads to abnormal occurrence of rock burst induced by face as the major factor in the accident. This research reveals the form of stress distribution in the destroyed layer of the thick conglomerate rock, analyzes the stope law of coupling for the pressure burst behavior law for the mining work face, and the choice of preventive measures to provide a theoretical basis and implementation.     

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。     

无煤柱分阶段沿空留巷煤与瓦斯共采方法与应用

针对深井高瓦斯低透气性煤层群的典型赋存特征,结合淮南矿区千米深井无煤柱煤与瓦斯工程实践,提出了改进Y型通风模式,即分阶段沿空留巷方法,完善了对共采工程的维控预应力锚固技术.工程实践表明:预应力锚固技术可以实现深井强动压开采过程中对沿空留巷和回风巷道围岩稳定的有效维控,至第1阶段结束,留巷顶板下沉量为144mm,两帮移近量为351mm,分阶段沿空留巷对共采巷道的维护时间缩短了4/5.减少了留巷变形速度稳定后累计变形的不利影响.超前工作面布置的瓦斯抽采工程中,单孔抽采瓦斯浓度(体积分数)达到40%,实现了煤与瓦斯共采.     

大定源瞬变电磁法在探测煤矿采空区富水性中的研究

大定源瞬变电磁法目前已成为许多矿区水文地质勘查的首选方法.而煤矿老窑采空区出水已成为矿井突水的显著特点之一,因此,本文使用大定源瞬变电磁法对采空区的富水性进行了研究.作者基于电磁场的基本理论研究了大定源瞬变电磁场响应分布规律,并通过一个工程实例证明了瞬变电磁法在探测煤矿采空区富水性方面是有效的.     

Stability control of gob-side entry retained under the gob with close distance coal seams

In multi-seam mining, the interlayer rock strata between the upper coal seam(UCS) and the lower coal seam(LCS) appear damage and strength weakening after mining the UCS. Ground stability control of the gob-side entry retaining(GER) under the gob with close distance coal seams(CDCS) is faced with difficulties due to little attention to GER under this condition. This paper focuses on surrounding rock stability control and technical parameters design for GER under the gob with CDCS. The floor rock strata damage characteristics after mining the UCS is first evaluated and the damage factor of the interlayer rock strata below the UCS is also determined. Then, a structural mechanics model of GER surrounding rock is set up to obtain the main design parameters of the side-roadway backfill body(SBB) including the maximum and minimum SBB width calculation formula. The optimal SBB width and the water-to-cement ratio of high water quick-setting material(HWQM) to construct the SBB are determined as 1.2 m and 1.5:1.0,respectively. Finally, engineering trial tests of GER are successfully carried out at #5210 track transportation roadway of Xingwu Colliery. Research results can guide GER design under similar mining and geological conditions.     

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.     

综合物探的奥陶系灰岩突水预警技术

为克服单一物探手段的局限,更准确地预测奥陶系灰岩突水风险,新安煤矿13151工作面采用瞬变电磁、直流电法、槽波地震和无线电波坑透等4种手段进行了综合物探.经比对物探结果,并结合地质与水文地质资料分析,4种物探异常区的重叠区域奥陶系灰岩水向上导升,低阻区条带分布,存在突水危险;煤厚变薄,可能受剪切滑动构造影响;槽波波速1 800 m/s以上,地应力(矿压)集中,利于围岩破坏.多种物探异常区的重叠区域的突水风险最大,是工作面防治水工作的重点.实例证明,综合物探可以弥补单一物探方法之不足,有效指导钻探验证、底板注浆及突水治理工作.     

大断面厚顶煤巷道围岩控制与支护参数优化

以山西大同同忻矿8104综放工作面回风巷(断面尺寸5.2 m×3.5 m)为工程研究背景,阐述了厚顶煤大断面巷道的围岩控制难题:顶煤裂隙发育、变形强烈、破坏范围大、易发生离层和冒顶等事故.结合现场地质生产条件,采用桁架锚索加强支护,并分析此支护系统的优越性:提供水平和竖直方向预紧力、变形闭锁、协同承载控制区域、锚固点稳.采用FLAC3D数值模拟计算了桁架锚索倾斜角度从10~40°变化过程中围岩变形规律:随着桁架锚索倾斜角度的增大,巷道围岩变形量先减小后增大,锚索倾斜20°时,巷道围岩变形量最小.表明回风巷受到采动影响后,顶底板最大移近量为395 mm,两帮最大移近量为263 mm.