深埋大跨度复合顶板煤巷失稳机理及控制技术

为了研究深埋大跨度复合顶板煤巷变形失稳机理及支护技术,以某矿2614改造下巷为工程背景,采用压力拱理论和数值模拟技术对巷道围岩变形规律进行了分析,设计了"锚杆(索)+金属网+M钢带+单体支柱"的支护方案,并开展了工业试验。结果表明,大跨度复合顶板巷道围岩失稳破坏分为分层剪切、挠曲离层、拉断破裂和垮落成拱4个阶段,巷道垮落拱高为2.5～3.8m,围岩变形量小于100 mm,锚杆和锚索拉力分别小于60 kN和350 kN,单体支柱压力小于13MPa,支护效果较好。

断层附近高应力巷道围岩变形机理及控制技术

针对山东许厂煤矿断层附近高应力回采巷道围岩变形破坏严重的问题,采用现场实测和数值模拟相结合的方法,分析了原回采巷道支护方案及失稳特征,研究断层构造、邻近采空区侧向支承压力与工作面回采超前支承压力多重叠加影响下回采巷道非对称稳定性规律;根据许厂煤矿3318工作面运输巷现场实际条件,提出了采用高强度、高刚度和非对称特性的新型锚网支护方案,该方案将3318工作面运输巷分为A和B 2种支护断面相间进行布置。通过现场试验得出:3318工作面运输巷采用高强度高刚度非对称新型锚网支护方案后,运输巷围岩变形量降低了70%以上,其中顶底板相对移近量由500 mm下降至120 mm左右,两帮相对移近量由800 mm下降至110 mm左右。

Research on the width of filling body in gob-side entry retaining with high-water materials

To determine the filling body's width along the gob-side remained roadway which is underneath the gob,the authors analyzed the interaction mechanism between the roof and the supporting body along the remained roadway, based on the elastic thin plate theory of the stope roof. The stress state and mechanical response of the filling body along the remained roadway were studied. Specifically, firstly, the supporting pressure of the coal pillar which is on one side of the gob-side remained roadway was deduced.Also, an equation that is used to calculate the width of the balance area in the stress limit state was acquired. Then, an equation that is used to calculate the roof cutting force on one side of the supporting body was obtained. By using FLAC3D, the authors investigated the displacement field and stress field response laws of rock masses around the roadway with different filling body's widths. The results show that with the filling body's width increasing, the supporting ability of the filling body increases.Meanwhile, the rock mass displacement around the roadway and the filling body deformation decrease.The better the filling body's supporting effect is, the higher the roof cutting force will be. When the filling body's width is larger than 3.0 m, its internal bearing ability becomes stable and the filling body's deformation became non-apparent. Finally, analysis shows that the filling body's width should be 2.5 m.Furthermore, the authors conducted field tests in the supply roadway 1204, using high-water materials and acquired expected outcomes.

Anchoring mechanism and application of hydraulic expansion bolts used in soft rock roadway floor heave control

Comparing with the resin bolt, the hydraulic expansion bolt has different anchoring mechanism and application advantage. According to the working mechanism of the hydraulic expansion bolt, its anchoring force is expressed in four forms including support anchoring force, tension anchoring force, expansion anchoring force and tangent anchoring force, and their values can be obtained on the basis of each calculation formula. Among them, the expansion anchoring force, which is the unique anchoring force of the hydraulic expansion bolt, can provide confining pressure to increase the strength of rock. Aiming at solving the problem of stability control in the soft rock roadway in Jinbaotun Coal Mine which has a double layer of 40 U-type sheds and cannot provide enough resistance support to control floor heave, the study reveals the mechanism of floor heave in the soft rock roadway, and designs the reasonable support parameters of the hydraulic expansion bolts. The observed results of floor convergence indicate that the hydraulic expansion bolts can prevent the development and flow of the plastic zone in the floor rock to control floor heave. Research results enrich the control technology in the soft rock roadway.

Movement and deformation laws of the overlying strata in paste filling stope

We combined the similar simulation with numerical simulation to analyze the movement and deforma- tion features of overlying strata caused by paste backfill mining, study the movement and deformation laws of the overlying strata in paste backfill mining, structural movement of the stope strata as well as the stope stress distribution laws. Furthermore, authors also explored the key factors to the movement and deformation of the overlying strata in paste backfill mining. The results indicate that a caving zone existed in the bending zone only in the overlying strata of the paste backfill mining. Compared with the roof caving mining, the degree of stress concentration and area of influence in the paste filling stope were apparently smaller. And the degree of destruction and area of the overlying strata decreased prominently. Also, there was no apparent strata behavior in the working face. Lastly, the filling ratio was the key to control the movement and deformation of the overlying strata. Combined with a specific engineering example, the author proved the reliability of the simulation results and provided a theoretical basis for the further extension of the paste backfill mining.

一流学科背景下采矿工程大学生创业能力提升策略研究

在响应节能减排和实现“双碳”目标的背景下,所有采矿从业者都应全力以赴推动能源资源的绿色可持续开发和使用。采矿工程专业学生创业能力的提升不仅需要学生有较高的综合素质水平、学科有完善的培养教育体系,还需要先进科研成果与创业教育紧密结合。该文针对采矿工程专业提出了制定问题引领式教育、打造“三创”培养模式、发挥“三永远”精神以及采取“三步走”培养策略,以期提升采矿工程大学生创业能力,并对一流学科支撑工科类专业建设提供借鉴。

膏体充填体假顶稳定性尖点突变分析

针对窑街三矿“三下”厚煤层压覆资源的安全开采问题,采用了下行分层膏体充填开采方法,通过构建膏体充填体假顶力学计算模型,得到了其厚度与极限强度关系式。利用尖点突变理论的势函数,推导了充填体假顶总势能,探究了充填假定的稳定性。采用FLAC3D数值计算软件,建立了下行分层膏体充填开采数值计算模型,研究了充填体假顶的移动变形特征。研究结果表明:充填体假顶的极限强度与其厚度呈幂函数负相关。充填体假顶厚度为3.2 m时,其极限强度为4.9 MPa,当充填体假顶厚度大于3.2 m后,其极限强度逐渐稳定于2.9 MPa。充填体假顶的总势能满足失稳判别式Δ≥0,不会发生突变失稳破坏。充填体假顶与下分层充填体的最大主应力均为1~2 MPa,小于其极限承载的抗压强度,且塑性区出现在下分层充填体层位,充填体假顶未发生剪切或拉伸破坏,所受的拉应力稳定于0.65 MPa,远小于充填体的许用拉应力。现场实测表明:下分层充填开采时,充填体假顶下沉量与上、下分层充填体的压缩量累计仅为75 mm。因此,在上分层充填体假顶的基础上开采下分层,充填体假顶能够承受上部围岩所施加的覆岩荷载,保证其自身稳定性,不会发生破断失稳,从而保证窑街三矿“三下”厚煤层压覆资源的安全开采。

膏体充填综采台阶煤壁稳定性半凸力学分析

通过细长杆失稳理论,建立台阶半凸力学模型,通过凸模柔度来判断与之相适应的临界载荷公式,并通过能量法近似求出模型的长度因数与稳定系数计算公式,进而得到台阶半凸力学模型失稳时所需的临界力、临界应力和纵向弯曲失稳校核判据;采用FLAC^(3D)数值模拟研究顶煤、中煤、底煤高度比分别为1∶1∶1,2∶2∶1两种不同割煤方案时煤壁前方支承压力、水平应力、水平位移以及工作面周围竖直应力分布.研究表明:煤壁发生片帮失稳所需的临界应力与其柔度有关,且煤壁柔度与长度因数呈正相关,长度因数与下台阶高度呈负相关,因此煤壁的柔度越小,煤壁片帮所需的临界应力就越高,抵抗失稳片帮的能力越强,所以可通过增加下台阶高度来提高煤壁抵抗失稳片帮的能力;不同方案割煤时,煤壁的垂直应力均小于片帮临界应力,因此不会发生失稳片帮;煤壁的上台阶高度减小,水平应力相应增加,位移量减小,下台阶的存在约束了上台阶煤体水平变形,使得煤壁前方支承压力变大,煤壁的承载能力增强,煤壁煤体稳定性增加,因此,可通过增加下台阶高度,提高煤壁稳定性.最终确定窑街三矿水平分层膏体充填开采的台阶高度比为1∶1∶1,为研究特厚急倾斜煤层采用短机身、大采高特殊采煤机割煤时所形成的台阶煤壁稳定性问题提供可靠理论支撑.

急倾斜特厚煤层水平分层大采高充填膏体与煤体协调承载特性研究

为了研究窑街三矿特厚急倾斜煤层水平分层膏体充填工作面煤壁的稳定性,首先基于压杆稳定力学模型,给出最大临界力Fct计算公式,进一步导出临界应力σct与分层高度的关系曲线,并给出了挠曲方程计算公式;其次建立FLAC3D数值计算模型,通过垮落法与充填法对比分析工作面前方煤壁的支撑压力、煤壁塑性区范围以及水平位移量与推进距离的关系;最后模拟分析了随着采充平行作业的推进,不同分层高度与工作面煤壁前方的支撑压力、煤壁塑性区范围以及水平位移量的关系。结果表明,当分层高度为4,5,6 m时,煤壁分别在距离底板3.12,3.9,4.46 m位置处挠曲最大,煤壁最大位移量分别为19,24,27 mm,且煤壁发生失稳片帮的临界应力分别为6.6,4.4,2.6 MPa,根据窑街具体情况,当分层高度为5 m,膏体充填工作面前方煤壁的最大支撑应力为3 MPa,未超过临界应力,即便煤壁向采空区最大移动24 mm也不会在工作面推进过程中发生煤壁片帮,且理论分析与数值计算结果基本一致,对窑街三矿特厚急倾斜煤层水平分层膏体充填开采具有借鉴意义。

基于智能反演的等效型煤构建方法、原理与技术

基于典型的松散煤体实际赋存状态,提出以原煤的坚固性系数为纽带,建立成型煤体的强度与原煤强度相似的关系,同时利用制备的型煤的孔隙率与原煤孔隙率相似的关系,综合构建室内成型煤体等效于现场松散煤体的方法。试验在测定原煤参数如成分、含水率、粒径级配基础上,选取了型煤的关键“构建参数”即成型压力、成型时间和成型水分,形成了系列成型工艺与方案,分析了松散软煤实验室制备型煤成型的机理。建立了基于人工智能算法的天牛须-进化支持向量机(BAS-ESVM)型煤参数智能反演模型,通过型煤数据库和模型反演结果表明,在给定现场软煤强度和孔隙率情况下,该智能模型能够精确反演室内型煤的成型压力、成型时间和成型水分。在该参数下制备的型煤强度和孔隙率与现场煤体参数高度吻合,验证了该模型的正确和可靠性。

近直立特厚煤层分段综放夹持煤柱冲击机理

以窑街三矿近直立特厚煤层水平分段综放开采为背景,建立了倾向剖面“夹持岩梁”力学模型与走向剖面“U-λ”岩板力学模型,揭示了近直立煤层水平分段开采的顶底板夹持煤柱冲击地压机理,分析了应力分布与塑性区演化规律,对工作面微震事件进行定性监测与时空定量监测。研究表明:当顶板岩层形成的“悬臂”结构达到一定长度极限,“U-λ”岩板断裂,对下方煤体产生冲击载荷,造成强烈的矿压显现;随着工作面不断向深部开采,煤柱所受水平应力增加,积聚在煤体中的弹性变形能释放,工作面下方煤体形成一定深度的剪切挤压张裂带破坏区;工作面下部为巨厚的底煤积聚大量的弹性应变能,产生塑性变形释放弹性能,导致底板突然底鼓、支架工作阻力升高。随着工作面向前推进,顶煤与其上方松散破碎煤岩体发生垮落,岩块在滑落和回转失稳过程中释放大量能量,对工作面造成动载扰动。

深部煤层超高水充填工作面充填体—支架—煤体协同承载机制

深井超高水充填开采岩层控制效果受充填体力学特性、支架与推进速度等因素影响,其中充填体—支架—煤体承载结构起关键作用,充填体—支架—煤体协同承载机制是当前深部煤炭资源绿色开采亟待解决的科学难题。为探究三者协同承载关系,以深部煤层超高水充填工作面为工程背景,分别进行了超高水固结体宏观力学与微观结构测试,得到充填体强度与时间变化的函数关系、宏观力学特性与细观渐进损伤关联机制;构建了充填体—支架—煤体协同承载力学模型,推导了超高水充填工作面顶板挠度微分方程,提出充填体—支架—煤体协同承载效果主要影响因素为工作面推进速度、支架支护强度和充填体水体积比,揭示了充填工作面充填体—支架—煤体协同承载机制,确定了合理工作面推进速度及支架工作阻力;采用FLAC软件建立充填体—支架—煤体协同承载数值模型,分别模拟在不同推进速度、支架支护强度、充填体水体积比条件下的承载特点,提出并应用了合理工作面参数。研究结果表明:当工作面推进速度小于1.8 m/d、支架支护强度高于0.64 MPa、充填体水体积比低于94.7%时,充填体达到了预期支撑强度,工作面覆岩应力降低、前方煤体应力集中系数减小、超前支护区巷道变形量小,充填体—支架—煤体协同承载有效提高了充填效果,为实现深部煤层安全高效绿色开采提供了科学依据。