共查询到20条相似文献，搜索用时 265 毫秒
1.
宁夏石嘴山矿区位于西部黄河流域,其煤矿采空区沉陷导致地表生态和环境问题频发,对其采煤沉陷分析将对西部黄河流域煤矿区的环境修复有一定的积极作用。为研究缓倾斜煤层采空区围岩应力与位移场演化特征,以宁夏石嘴山矿区为对象,基于FLAC3D数值模拟软件,建立缓斜煤层开采三维数值模型,计算分析采空区围岩应力、塑性区及位移变化规律,并基于两时相DEM叠加统计分析地表位移变化,与数值模拟结果进行相互验证。结果表明:地下开采引起应力重分布,采空区顶板及煤柱出现明显的应力集中现象,最大主应力呈现从煤层顶板向地表递减的变化趋势;越靠近采空区顶部的岩层垂直位移越大,随着远离采空区逐渐减少,开采完成后地表垂直位移最大值约12 m;随着采空区面积的不断增大,采空区四周及角隅处塑性区逐步延伸扩大,且以剪切破坏为主;地面沉陷盆地不对称,2个沉降中心均发生在沉陷盆地中部且偏下山方向,下山方向比上山方向影响范围更大;数值模拟计算的沉降量与两时相DEM叠加统计分析的变化量结果及趋势基本一致,研究成果可为煤炭安全开采提供参考依据,为地表沉降监测提供新方法。 相似文献
2.
基于煤层巷道开挖卸荷效应的底板冲击孕育过程研究 总被引：1，自引：0，他引：1
采用相似模拟和数值模拟研究了河南义马煤田跃进矿采掘影响下巷道底板的应力及变形规律,揭示底板冲击矿压发生前的孕育过程。研究表明,巷道底板冲击受煤层埋深、顶板条件、巷道施工布置方式等多因素影响。在巨厚坚硬上覆砾岩影响下,工作面开采增加了相邻工作面的应力水平。在厚煤层中巷道沿顶板布置留底煤,巷道开挖后,一定范围的煤层底板中的水平应力升高,垂直应力降低,增加了煤层失稳破坏的可能性。巷道开挖卸荷过程中,底板由于没有支护,垂直位移增加,底板的塑性区范围大于两帮,并产生了明显的拉伸破坏,容易使底板成为冲击破坏突破口。 相似文献
3.
深部大断面厚顶煤巷道围岩稳定原理及控制 总被引：6，自引：2，他引：4
针对深部高地应力、大断面、厚顶煤巷道围岩控制难题,采用理论分析、数值计算等方法研究了其变形破坏机制及其控制技术。研究结果表明,深部大断面厚顶煤巷道顶煤塑性区呈“拱形”或上宽下窄的“倒梯形”形态,直接顶塑性区则呈“矩形”形态,且存在肩角稳定区域。提出了“倒梯形”塑性区形成的层理面剪切破坏作用机制：在深部高应力（尤其是高水平应力）以及顶煤较大下沉产生的附加水平应力作用下,顶煤和直接顶之间的层理面发生剪切破坏,并引起其附近煤体破坏,促进了顶煤“倒梯形”塑性区的形成。基于此,提出了高强高预紧力锚杆和斜拉锚索梁联合支护围岩控制技术,认为斜拉锚索可锚固在肩角稳定区域,并起到限制顶煤与直接顶岩层之间层理面的剪切变形、阻止顶煤塑性区由“拱形”向“倒梯形”发展的作用。研究成果成功应用于工程实践 相似文献
4.
深部岩体处于三维应力场中受开挖扰动影响钻孔、巷道围岩处于明显的真三轴应力状态。钻孔抽采技术是煤矿广泛用于瓦斯治理的重要措施,钻孔周围塑性区是瓦斯流动的优质通道,研究钻孔围岩塑性区特性对于抽采钻孔的优化布置至关重要。为研究钻孔围岩的塑性区特性,基于广义平面应变理论分析围岩应力分布,比较几种常用强度准则（MC、Mises、D-P、MLC、SMP）的适用性和精确性,对比试验结果表明,MLC准则能较好地表征岩石的真三轴强度特性。基于MLC准则推导了围岩塑性区半径公式,分析偏应力、中间主应力、岩石内摩擦角、岩石黏聚力和钻孔半径对增透半径的影响,结果表明,增透半径随着偏应力的增大而增大,随中间主应力的增加先减小后增大,随岩石内摩擦角、岩石黏聚力的增加而逐渐减小,随钻孔半径的增加而线性增大。研究结果可为实际工程中巷道支护、煤层瓦斯抽采等技术的参数设计等提供重要参考。 相似文献
5.
Baotang Shen 《Rock Mechanics and Rock Engineering》2014,47(6):2225-2238
Roadway instability has always been a major concern in deep underground coal mines where the surrounding rock strata and coal seams are weak and the in situ stresses are high. Under the high overburden and tectonic stresses, roadways could collapse or experience excessive deformation, which not only endangers mining personnel but could also reduce the functionality of the roadway and halt production. This paper describes a case study on the stability of roadways in an underground coal mine in Shanxi Province, China. The mine was using a longwall method to extract coal at a depth of approximately 350 m. Both the coal seam and surrounding rock strata were extremely weak and vulnerable to weathering. Large roadway deformation and severe roadway instabilities had been experienced in the past, hence, an investigation of the roadway failure mechanism and new support designs were needed. This study started with an in situ stress measurement programme to determine the stress orientation and magnitude in the mine. It was found that the major horizontal stress was more than twice the vertical stress in the East–West direction, perpendicular to the gateroads of the longwall panel. The high horizontal stresses and low strength of coal and surrounding rock strata were the main causes of roadway instabilities. Detailed numerical modeling was conducted to evaluate the roadway stability and deformation under different roof support scenarios. Based on the modeling results, a new roadway support design was proposed, which included an optimal cable/bolt arrangement, full length grouting, and high pre-tensioning of bolts and cables. It was expected the new design could reduce the roadway deformation by 50 %. A field experiment using the new support design was carried out by the mine in a 100 m long roadway section. Detailed extensometry and stress monitorings were conducted in the experimental roadway section as well as sections using the old support design. The experimental section produced a much better roadway profile than the previous roadway sections. The monitoring data indicated that the roadway deformation in the experimental section was at least 40–50 % less than the previous sections. This case study demonstrated that through careful investigation and optimal support design, roadway stability in soft rock conditions can be significantly improved. 相似文献
6.
泥化弱胶结软岩地层中矩形巷道的变形破坏过程分析 总被引：2，自引：0，他引：2
在西部地区,一定数量的矿区处于泥化弱胶结软岩地层,此类软岩胶结性差、强度低、遇水泥化。矩形是采区巷道的常用型式,但其断面受力不均、稳定性差。在上述软岩地层中的矩形巷道承载力低、变形量大、变形持续时间长,给煤矿的安全生产带来极大困难。以内蒙古新上海一号煤矿皮带顺槽矩形巷道为背景,运用FLAC3D软件中的Cvisc黏弹塑性模型,对矩形巷道的变形破坏进行了数值模拟,并将模拟结果与现场监测结果对比分析。结果表明:巷道开挖支护后,受断面形状影响,矩形巷道四角出现压应力集中和顶板受拉区,巷道顶板下沉量大,底板底臌严重,两帮向巷道挤出;受围岩岩性影响,围岩进入塑性的时间快短、范围大,塑性区超出了支护体的作用范围,造成锚杆(索)的锚固效果难以完全发挥,围岩出现整体滑动的现象;巷道变形呈现出流变变形的特性,变形量随时间持续增加,持续的蠕变变形超出了支护体的可控范围,最终引起巷道的失稳破坏。 相似文献
7.
为了防止透巷作业时地层水和钻井液沿钻孔突然涌入巷道,造成井下被困人员二次伤害,采用ABAQUS岩土数值模拟方法,以山西坪上煤矿3 号煤层巷道地面救援井为例建立模型,研究钻井动力扰动条件下巷道顶板围岩塑变特性规律,优化安全透巷距离。结果表明:动力扰动造成顶板围岩位移变形和塑性破坏,且以钻孔中心呈对称的锯齿形分布;轴向作用力对透巷顶板围岩的影响较大,安全透巷距离取值为16.53 m。模拟结果为优化安全的透巷距离提供了参考,实现了安全高效透巷的目的,为救生舱在救援井中安全下放、提升作业提供了保障。 相似文献
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9.
Tu Hong-sheng Tu Shi-hao Wang Chen Hao Ding-yi Zhu De-fu 《Environmental Earth Sciences》2018,77(13):509
Roadways in coal mines normally have two vertical side walls and a semicircular arch-shaped roof when viewed in cross section, a design conducive to the stability of surrounding rocks. The North 1 main roadway in Duerping Coal Mine has suffered severe damage and the conventional support method employed there is incapable of ensuring long-term stability of the surrounding rocks. This study provides a mechanical analysis of this vertical-wall, semicircular-arch (VWSA) roadway using a mechanical model. Formulas describing stresses in the rocks surrounding a VWSA roadway were derived through complex analysis. The stress distribution in the surrounding rocks was then predicted using the formulas. Based on the results, a double-shell support structure consisting of an internal shell, a flexible interlayer, and an external shell was developed as a new technique to stabilize surrounding rocks. The functional mechanisms of the three parts and the specific construction procedure are detailed in this paper. Moreover, the key technical parameters were optimized through a comparative analysis of the surrounding rock’s deformation behavior for different shell and interlayer thicknesses. After implementation of this technique, the floor heave, relative displacement between two sides, and roof lowering in the North 1 main roadway decreased to 82, 185, and 161 mm, respectively, which meet the requirements for long-term service. This verifies the effectiveness of the proposed technique in surrounding rock control. 相似文献
10.
为研究深部煤层开采底板破坏形态,提出考虑围岩应变软化和采空区接触的FLAC3D有限差分数值方法,以河北开平煤田林西矿2023工作面底板实测导水裂隙带为工程背景,结合朗肯土压力理论定性分析,研究深部煤层底板破坏特征。结果表明:采用应变软化本构关系代替常用摩尔–库伦本构关系能够对围岩塑性破坏后的力学状态更准确表述;采用“应变软化–空–弹性”模型转变的方法,达到模拟采空区顶板垮落后应力传递的效果,弥补了以往煤层开采模拟中采空区垮落后顶底板不接触的固有缺陷;通过采空区顶底板接触与否条件下应力、位移的对比,发现采空区是否接触对数值结果影响巨大,突出考虑采空区接触的必要性;根据模拟结果中塑性剪切应变率的变化,实现了底板滑移面的三维显示,形态为斜向采空区的半包围面状结构;结合朗肯土压力理论将底板塑性区与主动区、过渡区和被动区对应,3个区破坏形式分别为剪切破坏、剪切破坏、拉张与剪切的交互破坏。提出的考虑围岩应变软化及采空区接触的FLAC3D数值方法对煤层开采模拟实现了优化,并可为其他大变形后需考虑接触的工程模拟提供参考。 相似文献
11.
采掘扰动是诱发冲击地压灾害的重要因素,深部采掘扰动区域则受冲击与巷道变形的双重威胁,针对该技术难题,本文研究了线性密集切顶防冲护巷技术。基于关键层理论分析了倾斜煤层关键层倾向破断结构特点,表明关键块B的空间状态是控制正在开采的工作面与迎采巷道矿压显现的关键,给出了采掘扰动工况下的最佳关键块断裂线位置。基于COMSOL模拟研究了不同装药直径下的应力峰值分布规律,结果表明:爆破后应力以指数函数形式快速衰减,给出了不同装药直径下应力峰值分布的拟合公式;致裂半径与装药直径呈幂函数的正相关关系;以顶板岩石抗拉强度为指标值,确定了爆破孔直径对应的最优间距。现场设计实施了不同技术参数的切顶方案,结果表明,相比于传统的深孔爆破,线性密集切顶两钻孔之间能够形成贯通裂隙,从而控制关键层的破断方式,因此钻孔间距是影响防冲与护巷效果的关键参数。通过巷道围岩观测与微震监测,表明线性密集切顶技术能够有效减弱迎采巷道的围岩变形,同时降低正在开采的工作面矿压显现与冲击危险性,现场实践验证了理论与模拟结果,可为类似条件工程提供借鉴。 相似文献
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为研究开采上保护层对巨厚砾岩断裂诱发冲击的防治作用,根据跃进煤矿25采区的地质条件和采掘条件,将25110工作面下巷作为研究对象,从理论上分析了动静载叠加诱发冲击矿压的机制以及开采上保护层后的防冲原理,数值模拟研究了未开采上保护时和开采上保护层后在同等强度的动载扰动应力的影响下巷道底板的位移、速度、应力以及塑性区的变化规律,进行相似模拟试验研究了人工震源的作用下未开采上保护时和开采上保护层后巷道底板的加速度和动应力响应规律。结果表明,上保护层开采后能够有效地释放围岩内部的高应力,且采空区顶板自然垮落,形成的软弱松散岩层结构,能够更好地起到对动载扰动应力波的衰减作用,从而降低了冲击矿压发生的可能,一定程度上能够较好地防治冲击矿压。研究成果对巨厚砾岩下冲击矿压的防治具有一定指导意义。 相似文献
13.
This paper uses two-dimensional boundary element method (BEM) numerical modeling to analyze the deformation and failure behavior of a coal seam and to understand the nature of gas flow into a roadway entering the Barapukuria coal mine in Bangladesh. The Barapukuria basin contains Permian-aged Gondwana coals with high volatile B bituminous rank. Three models (A, B, and C) are presented here. Model A assumes horseshoe-shaped geometry, model B assumes trapezoid-shaped geometry, and model C assumes horseshoe-shaped geometry coupled with a roof fall-induced cave generated by the break-up of rock materials along the vertical dimension of an igneous dyke. The simulation results show that there is little difference in strata deformation between models A and B. In model A, there is no horizontal tensional stress and the overall horizontal stress patterns are compressive, while the distribution and magnitude of vertical stress show higher tensional stresses on the immediate rib sides and floor. In model B, both horizontal and vertical stress distributions indicate low to medium tensional stresses on the immediate roof, floor, and rib sides, but compressive stresses are prominent toward the interior of the coal seam. Deformation vectors indicate that failure extends laterally to about 7.5 m around the excavation geometry.On the contrary, for model C, the distributions and magnitudes of horizontal and vertical stress show higher tensional stresses in both rib sides of the roof fall zone. The deformation around the dyke-induced perturbation zone affects a large volume of coal. The deformation vectors with high magnitudes are nearly horizontal and propagate laterally up to 30 m; whereas, low-magnitude deformation vectors extend about 25 m toward the roof and 20 m toward the floor. The vertical tensional displacement, which is concentrated in the floor and the left and right hand sides of the roof, propagates about 30 m on both sides and about 22 m in the floor. From these simulation results, it is thought that the extension of the dyke-induced perturbation zone toward the roof, floor, and rib sides of the entry roadway initially creates small tensional cracks that gradually grow into large-scale tensional features. These features could also be responsible for high concentrations of gas, which are emitted into the mine from fractured coals due to insufficient mine ventilation and low atmospheric pressure. 相似文献
14.
特厚煤层小煤柱沿空掘巷数值分析及应用 总被引：1，自引：0，他引：1
沿空掘巷开采技术成功的关键主要取决于采场覆岩稳定的时间和沿空掘巷的位置。采场采动岩体运动导致围岩应力重新分布,动态采场应力作用于围岩并使其状态发生灾变是发生矿山灾害的根本原因。特厚煤层分层综采巷道布置（包括内错、外错和垂直）,合理确定煤柱尺寸、巷道支护方式和参数选择能够最大可能发挥围岩的自承能力,是提高巷道稳定的重要保证。在稳定的内应力场范围内布置小煤柱护巷,能够明显提高巷道围岩稳定状态,减少巷道维护费用。通过理论分析、数值模拟和现场实测等方法,对特厚煤层下分层沿空掘巷小煤柱不同巷道布置设计,通过煤柱的应力、应变和位移进行对比分析,确定特厚煤层下分层沿空掘巷合理的巷道位置和煤柱尺寸及上覆岩层防控技术,并得到工程验证是正确可靠的,从而为特厚煤层小煤柱开采技术提供了重要的科学依据。 相似文献
15.
预测构造煤发育区对矿井瓦斯突出预测具有重要意义。以阳泉矿区新景矿3号煤层为研究对象,根据其地质赋存条件,建立了相应的岩性不均衡力学模型,基于FLAC3D数值模拟软件,研究了顶板砂岩透镜体存在情况下3号煤层围岩应力分布规律。结果显示:砂岩透镜体的存在使得煤岩地层的应力、位移分布不均,在透镜体影响范围内呈现应力集中现象,致使该区域煤层发生塑性变形;岩性不均衡条件下3号煤层的构造煤发育,进而证实了新景矿3号煤层顶板砂岩对构造煤发育的控制作用。 相似文献
16.
煤矿井下石门揭煤诱发的煤与瓦斯突出是一种十分复杂的矿井地质动力灾害,严重威胁着煤矿安全高效生产。选取辽宁红山煤矿为工程背景,运用FLAC3D模拟分析矿井南翼瓦斯突出危险区石门揭12煤过程中围岩力学响应特征,揭示石门揭煤突出机理,提出瓦斯预抽措施配以改进金属骨架的综合防突技术方案。研究结果表明:石门揭12煤期间,工作面超前支承压力随石门掘进动态前移,距煤层6 m范围内,工作面前方围岩掘进扰动强烈,煤体出现明显应力集中现象,垂直应力为15~19 MPa,已超过煤体强度。同时,石门工作面围岩变形量急剧增大,顶板下沉位移为15~92.22 cm,煤体弹性变形能积聚;工作面围岩塑性区范围也迅速扩展,在石门中线垂直剖面上的面积为10~50 m2,裂纹贯通形成碎煤射流通道。综合模拟结果可知,石门揭12煤过程中煤体承载较高集中应力和瓦斯压力,且储存大量弹性变形能,极易诱发突出。基于此,在传统瓦斯预抽防突措施的基础上,对现有金属骨架防突技术进行改进,使其同时具备瓦斯预抽、煤体固化和超前支护的综合防突作用,并通过现场应用取得了良好效果,为类似条件石门揭煤防突研究提供重要借鉴和参考。 相似文献
17.
深部厚顶煤巷道围岩变形破坏机制模型试验研究 总被引：2，自引：0，他引：2
为研究深部厚顶煤巷道围岩变形破坏特性及其机制,以赵楼煤矿千米深井厚顶煤巷道为工程背景,开展了大比尺地质力学模型试验,对让压型锚索箱梁支护系统作用下的巷道围岩位移、应力演化规律进行的研究表明：巷道顶底板围岩竖向应力释放较两帮剧烈,水平应力释放反之,巷道顶板中部围岩是顶板竖向应力释放的主要部位。通过与现场试验结果对比验证,总结出深部厚顶煤巷道围岩变形破坏的3个主要特征：顶板变形破坏较两帮和底板严重、顶板围岩变形破坏主要发生在煤岩交界面以下的煤体中、巷中是顶板变形破坏的关键部位,并进一步分析了相应机制：顶板煤岩松软破碎、自承能力差、顶板及其巷中竖向应力释放相对更为剧烈、矩形巷道顶板受力状态差等因素,导致顶煤所受径向应力低,碎胀变形剧烈,且弯曲变形、离层严重,顶板受力结构恶化,最终导致顶板控制困难。 相似文献
18.
为深入探讨硬煤的煤与瓦斯突出机制,对深部硬煤掘进工作面煤与瓦斯突出的相关理论和模型试验进行研究。根据断裂力学、岩石力学及煤与瓦斯突出有关理论,提出深部开采过程中硬煤掘进工作面薄板理论假设,并将该理论应用于深部硬煤掘进工作面煤与瓦斯突出模拟试验研究。对硬煤掘进工作面薄板理论分析,认为工作面尺寸、煤的弹性模量、围岩侧压系数、瓦斯压力等因素对硬煤掘进工作面突出具有较大影响。试验结果表明,在围岩应力、煤的坚固性系数较大的情况下,硬煤突出临界条件主要受围岩应力、煤的弹性模量、围岩侧压系数及工作面尺寸等因素影响,而受瓦斯压力影响相对较小;在围岩应力、试样的坚固性系数较大且煤的弹性模量和侧压系数稳定不变的情况下,发生突出的临界轴向应力随模拟工作面尺寸增大而近似呈线性减小。试验结论基本符合本硬煤突出薄板模型理论公式,在一定程度上验证了硬煤掘进工作面煤薄板模型理论及硬煤掘进工作面突出机制假设。 相似文献
19.
Summary A method of measuring ultrasonic wave properties in rocks during the complete stress-strain process is described. The relevant experimental laboratory study, to reveal the change of the amplitude spectrum parameters with strain (or stress) has been carried out. A preliminary study was conducted on the application of the ultrasonic measurement technique at a belt conveyor roadway of the north wing in Baodian coal mine, Shandong province. A borehole ultrasonic device with dry coupling was developed to provide better coupling and more accurate measurement data in comparison with those of a water coupled situation. Based on the interrelations between the complete stress-strain properties of specimens and their wave properties, the structural properties of surrounding rocks, the range of yield zones, and the change of stresses within the rocks surrounding a roadway which was subjected to mining influence of upper longwall face were analysed. Amplitude spectrum parameters were used to give a better prediction of the physico-mechanical state of the surrounding rocks. 相似文献
20.
通过对沁水盆地安泽区块煤层气地质条件和储层条件的深入分析,探讨了该区煤层气的富集规律及主要影响因素。研究发现,煤的岩石学特征、构造、顶底板岩性是影响煤层气富集的主要因素。总体上,安泽区块煤储层含气量受煤阶影响,表现为:煤的变质程度越高,吸附能力整体增强,含气量增大。局部区域,煤层气含量受煤层埋深、断层、褶皱及煤层顶底板岩性等综合因素的影响。在构造平缓带,煤层气含量随埋深增大而增大;在构造活动带,正断层上升盘含气量明显低于下降盘含气量,断层对煤层气的逸散作用明显。此外,泥岩顶底板封盖较砂岩顶底板封盖能力强。 相似文献