Application of open-pit and underground mining technology for residual coal of end slopes

Given the conditions of residual coal from the boundary of a flat dipping open-pit mine,which uses strip areas mining and inner dumping with slope-covering,we propose an open-pit and underground integrated mining technology for residual coal of end slopes.In the proposal a conveyance road and ventilation conveyance near the slope are built,corresponding to the pit mining area and the surface coal mine dump,as well as an interval haulage tunnel and air-inlet tunnel.The outcome shows that such mining method may reduce the effect to slope stability from underground mining,it does not affect the dumping advance and has a high recovery rate of residual coal resources.The working face is timbered by single hydraulic props,transported by a scraper conveyor and supported by coal walls.This method of mining is one of layered top coal caving,with high resource recovery,low production cost where positive economic benefit can be realized.

Thermal recovery process of a backfilled open-pit in permafrost area at the Gulian strip coal mine in Northeast China

Timely and proper backfilling of open-pits in strip coal-mines has been an effective measurement for the recovery of the hydrothermal regimes and ecological environment in permafrost regions. In this study, numerical simulations and statistical regressions were applied for analyzing the recovery processes of the backfill and its major influencing factors for the thermal equilibrium in recently backfilled open pits at the Gulian strip coalmine in Mo'he, Northeast China. Results show that the thermal recovery time of backfilled areas is positively correlated to the backfill depth(BD) of the soils, the backfilled soil temperature(BST), and the mean annual ground surface temperature(MAGST); meanwhile, climate warming can impact on thermal regimes of the backfill area. The impact of climate warming on ground temperature of the backfill will show up significantly in about 50 years afterbackfilling(BD at 10.0 and 20.0 m, BST at 20.0°C) under the climate warming scenario(CWS) of 0.025°C·year ^(-1). Grey-relation analyses show that the sensitivity of the backfill recovery time declines in the order of the BD, BST and MAGST. On the basis of the abovementioned studies, the layer-by-layer backfilling in cold seasons is advised for more effective and more rapid recovery of thermal regimes of the backfilled open-pits in cold regions.

相邻空区影响下三软巷道变形破坏规律与煤柱留设宽度研究

为了探究相邻空区影响下三软煤层巷道掘进时不同煤柱宽度下巷道围岩变形破坏规律,采用理论计算、数值模拟、物理相似模拟与现场实测相结合的研究方法,分析存在临空区后不同区段煤柱宽度下巷道围岩应力演化规律、塑性破坏范围以及位移分布特征。结果表明:临空区是造成巷道掘进后非对称破坏的主要原因,使煤柱主应力方向与垂向夹角增大,巷道两帮应力呈煤柱侧大于实体煤侧的非对称分布特征;三软巷道破坏形式以剪切破坏为主,破坏主体为两帮,随着煤柱宽度增大,主应力方向与垂向夹角减小,巷道围岩破坏程度降低,临空区对巷道不同位置的影响程度不同,巷道中部围岩破坏程度大于端头处且煤柱侧破坏程度大于实体煤侧;煤柱宽度增大对巷道围岩应力以及煤柱破坏的改善程度有限,现场结果显示当煤柱宽度为20 m时巷道正常维护满足需求。

冲击地压煤层矿井间临近工作面相互采动影响分析

为了对冲击地压煤层矿井间临近工作面相互采动影响进行分析,以义桥煤矿3309工作面和唐阳煤矿432工作面为研究背景,采用数值模拟的研究方法,从巷道侧垂直应力和覆岩垂直位移两个方面研究了两工作面相互采动的影响。当两工作面开采时,3309工作面运输顺槽侧的应力增大了26.0%~28.0%,顶板位移增大了7.3%~10.1%,432工作面运输顺槽侧的应力增大了31.8%~48.8%,顶板位移增大了12.8%~19.2%。通过上述分析可以得出冲击地压煤层矿井间临近工作面相互采动时,对工作面应力集中分布及顶板运移规律均具有明显的影响。并在采取相应卸压措施的基础上,提出3条关于影响较大区域防冲补强措施的建议,以降低两工作面相互采动影响,确保工作面安全生产。

蒙陕深埋煤层首采工作面顶板富水性和涌水量差异研究

针对蒙陕接壤区存在水文地质条件不清、水害问题多发、水资源漏失严重等问题,通过分析区内呼吉尔特矿区4个矿井首采工作面顶板地质水文地质特征、回采过程中涌水量变化及差异性,查清了矿区煤炭开采初期扰动下的水文地质条件,结果表明:四个矿井首采工作面涌水量,均随着工作面回采呈逐渐增加趋势,其中葫芦素和巴彦高勒矿井首采工作面最大涌水量分别为645.0 m^(3)/h和494.0 m^(3)/h,且七里镇砂岩含水层不同区域存在富水性差异,导致涌水量的增加呈台阶式,波动性较大,与该区域七里镇砂岩含水层厚度较薄、富水性较弱的特征一致;门克庆和母杜柴登矿井首采工作面最大涌水量分别为1372.0 m^(3)/h和938.0 m^(3)/h,且七里镇砂岩含水层整体富水性较强、富水性较均一,涌水量的增加呈平稳增加态势,波动性较小,与该区域顶板七里镇砂岩含水层厚度较大、富水性较强的特征一致。

近距离冲击地压煤层开采遗留煤柱与断层复合影响下冲击危险性研究

我国主要冲击地压矿井往往同时赋存多层可采煤层,多煤层协同安全开采是事关我国能源安全的重要课题。近距离冲击地压煤层开采时,上部煤层留设的煤柱承载了较高的上覆岩层载荷,给下部煤层开采带来了较大的风险。当遗留煤柱下发育断层时,该遗留煤柱导致的应力集中区与断层围岩附近的应力异常区产生的复合作用对工作面开采产生巨大影响。本文以陕西彬长大佛寺煤矿40201工作面为研究对象,理论分析了上煤层遗留煤柱和断层复合作用对下部冲击地压煤层开采时冲击危险性的影响,采用地震波层析成像技术和微震监测技术,分别探明了遗留煤柱和断层复合作用下工作面围岩静载荷、动载荷分布规律。研究结果表明:煤层中的断层破碎带在上覆遗留煤柱作用下产生的静载荷集中区域会向断层两盘远处转移,使得断层更易发生滑移失稳;在遗留煤柱和断层的复合作用下,工作面“见方”区域来压早于理论预测结果,且来压强度增大;工作面动载显现以遗留煤柱下区域为主,遗留煤柱的存在增大了工作面超前支承压力的影响范围。本文研究可对类似条件下的冲击地压煤层开采提供一些借鉴。

下霍煤矿2307综采面瓦斯抽采技术应用

通过分源预测法计算得出2307工作面绝对瓦斯涌出量为2.25 m^(3)/t,瓦斯主要来源于本煤层。为了避免回采期间2307工作面回风隅角、回风巷瓦斯超限,采用本煤层抽采为主、现采采空区抽采及邻近层抽采为辅的瓦斯抽采方式,并设计了各种抽采钻孔、管路参数,抽采本煤层、邻近层及采空区瓦斯,抽采后工作面回风隅角、回风巷瓦斯浓度分别为0.45%、0.25%,瓦斯抽采效果良好,保证了工作面回采安全。

邻近煤层同采巷道布置及安全错距优化研究

针对苏村煤矿6煤、10煤分层同采错距不合理,上下两工作面开采受动压的相互影响,造成工作面冒顶、片帮、支架折损等问题,通过采用理论分析、数值模拟以及工程应用相结合的方法对邻近煤层同采工作面巷道布设位置及错距进行了优化研究。研究结果表明:考虑不同开采方式下10煤层巷道围岩应力变化特征,确定上下煤层巷道采用对齐式布置;考虑下煤层开采时覆岩移动,下煤层区段煤柱应大于16.7 m;上下煤层同采时工作面合理错距在45 m左右。研究结果应用工程实践表明,同采期间工作面支架受力平稳,实现了邻近煤层安全高效同采,对类似条件下的煤层群开采具有重要的指导意义。

Stability analysis of rib pillars in highwall mining under dynamic and static loads in open‑pit coal mine

The retained coal in the end slope of an open-pit mine can be mined by the highwall mining techniques.However,the instability mechanism of the reserved rib pillar under dynamic loads of mining haul trucks and static loads of the overlying strata is not clear,which restricts the safe and efcient application of highwall mining.In this study,the load-bearing model of the rib pillar in highwall mining was established,the cusp catastrophe theory and the safety coefcient of the rib pillar were considered,and the criterion equations of the rib pillar stability were proposed.Based on the limit equilibrium theory,the limit stress of the rib pillar was analyzed,and the calculation equations of plastic zone width of the rib pillar in highwall mining were obtained.Based on the Winkler foundation beam theory,the elastic foundation beam model composed of the rib pillar and roof under the highwall mining was established,and the calculation equations for the compression of the rib pillar under dynamic and static loads were developed.The results showed that with the increase of the rib pillar width,the total compression of the rib pillar under dynamic and static loads decreases nonlinearly,and the compression of the rib pillar caused by static loads of the overlying strata and trucks has a decisive role.Numerical simulation and theoretical calculation were also performed in this study.In the numerical simulation,the coal seam with a buried depth of 122 m and a thickness of 3 m is mined by highwall mining techniques.According to the established rib pillar instability model of the highwall mining system,it is found that when the mining opening width is 3 m,the reasonable width of the rib pillar is at least 1.3 m,and the safety factor of the rib pillar is 1.3.The numerical simulation results are in good agreement with the results of theoretical calculation,which verifes the feasibility of the theoretical analysis of the rib pillar stability.This research provides a reference for the stability analysis of rib pillars under highwall mining.

Roadway failure and support in a coal seam underlying a previously mined coal seam

The influence of an upper,mined coal seam on the stability of rock surrounding a roadway in a lower coal seam is examined.The technical problems of roadway control are discussed based on the geological conditions existing in the Liyazhuang Mine No.2 coal seam.The stress distribution and floor failure in the lower works after mining the upper coal is studied through numerical simulations.The failure mechanism of the roof and walls of a roadway located in the lower coal seam is described.The predicted deformation and failure of the roadway for different distances between the two coal seams are used to design two ways of supporting the lower structure.One is a combined support consisting of anchors with a joist steel tent and a combined anchor truss.A field test of the design was performed to good effect.The results have significance for the design of supports for roadways located in similar conditions.

倾斜煤层含矸煤柱区应力状态及防冲技术研究

针对倾斜煤层分层开采综放工作面临空侧含夹矸层巷道变形量大、冲击危险性高的问题,构建了侧向悬顶临空煤柱受力模型,运用数值模拟方法对工作面回采过程中煤柱区域围岩应力场和塑性区变化进行研究。研究结果表明:在煤柱弹性变形阶段,煤柱支撑力、变形量、煤柱积聚弹性能随着悬顶长度的增大而增大;临空煤柱在巷道区域存在夹矸弱层时,沿夹矸面产生的应力集中区致使巷道变形量增大,诱使周围煤岩运动加剧;当临空侧煤柱上方巷道顶板不易发生破坏时,可形成弹性能的良好载体和传递通道,造成巷道应力集中,加剧冲击地压发生危险性。同时,针对含矸临空煤柱自身抗破坏能力较差问题,提出远近结合、分批次的卸压方式,制定了顶板预裂、煤体爆破方案,有效降低巷道帮鼓变形量,微震震动点向远离工作面方向上方顶板偏移,冲击地压危险程度明显降低,有效保证工作面安全回采。

砚北煤矿特厚易自燃煤层邻近采空区瓦斯抽采与煤自燃耦合研究

砚北煤矿特厚易自燃煤层采用分层开采,在工作面推进过程中因周期来压造成工作面上隅角瓦斯瞬时超限,目前主要通过瓦斯抽采解决该问题,但邻近采空区抽采易引起采空区漏风,可能导致遗煤及下分层煤发生自燃。为分析采空区瓦斯抽采对遗煤自燃的影响及优化抽采参数,编制了瓦斯抽采、漏风、氧化升温耦合脚本文件,建立了邻近采空区瓦斯抽采耦合氧化升温数值计算模型,并利用该模型模拟了不同抽采条件下邻近采空区瓦斯浓度分布、温度分布及氧气浓度分布规律,综合考虑抽采效率和防止煤氧化自燃,研究结果表明:抽采钻孔高度35 m、抽采负压7 kPa时瓦斯抽采效果最佳。研究结果可为特厚易自燃煤层工作面上隅角瓦斯治理及邻近采空区瓦斯抽采设计提供技术参考。

相邻工作面采动影响下小煤柱巷道围岩应力时空演化特征研究

采动工作面小煤柱沿空掘巷受自身掘进和相邻工作面回采的双重扰动影响,巷道应力环境复杂,常规支护方式不能维持巷道围岩的稳定。以山西经坊煤矿3-5092回风顺槽为工程背景,采用分段支护的方法对巷道围岩的支护方式进行优化,并基于锚杆无损检测系统对巷道围岩的支护效果进行评价。结果表明:实体煤掘进阶段受掘进扰动的影响,稳定期内巷道围岩应力将重新分布,在巷道变形过程中锚杆能发挥主动支护的效果;在相邻采动工作面沿空掘巷相遇阶段,巷道围岩发生结构性应力调整,帮部锚杆的工作载荷整体高于顶部锚杆,需对煤柱侧巷道帮部进行加强支护;沿空掘巷阶段受掘进扰动的影响,锚杆轴力增大但增幅较小,此阶段巷道稳定性较好。通过现场工业性试验与锚杆轴力监测,揭示了不同阶段巷道围岩的时空应力演化特征,验证了分段支护设计方案的合理性。

近距离高瓦斯煤层群首采层“一面四巷”瓦斯治理技术

针对近距离高瓦斯煤层群首采层回采工作面“U”型通风条件下,邻近层瓦斯通过煤岩体卸压产生的裂隙大量涌入到上隅角并进入回风流造成瓦斯超限的问题,以东于煤矿03X04回采工作面为研究对象,分析了回采工作面“U”型通风条件下采空区卸压瓦斯运移规律,从而确定了“回采工作面运输、轨道巷+高、底抽巷”相结合的“一面四巷”联合瓦斯治理技术方案。现场应用结果表明:回采工作面瓦斯抽采率达到81%,本煤层瓦斯含量下降了33%,完全处于卸压范围内的边部底抽巷拦截钻孔抽采纯量达到单孔0.02~0.03 m3/min,瓦斯抽采浓度最高达90%,抽采纯量提升2倍以上,大幅度减小了下邻近层瓦斯涌入回采工作面和上隅角,回采工作面轨道巷和边部底抽巷回风流瓦斯浓度稳定在0.2%~0.4%,上隅角瓦斯浓度处于0.3%~0.4%,有效地解决了回采工作面“U”型通风条件下上隅角和回风流瓦斯超限的问题,保证了矿井安全高效生产。

大采高大断面迎采沿空巷道窄煤柱宽度研究

根据山西马堡煤矿地质条件,通过极限平衡理论、内外应力场理论计算出迎采巷道煤柱宽度范围为6.48~8.97 m.采用FLAC3D数值模拟软件,分别模拟了煤柱宽度为5~9 m时,在15202运输顺槽掘进过程中,煤柱应力分布、塑性区分布及迎采沿空巷道围岩变形规律,结果表明:随着煤柱宽度的增加,煤柱峰值应力及塑性区范围不断减小,煤柱宽度为7 m以后,峰值应力减小趋势和塑性区变化均不明显,围岩变形逐渐趋于稳定,综合考虑安全开采和资源高效利用,最终确定煤柱宽度为7 m.通过模拟煤柱不同位置在采掘过程中的应力变化,确定采掘应力叠加影响范围为采掘间距30~-30 m,并结合15202运输顺槽不同位置的围岩变形情况,给出了合理的支护建议。

综放开采矸石注浆充填技术的研究与应用

阐述了鄂尔多斯市国源矿业开发有限责任公司龙王沟煤矿特厚煤层放顶煤开采条件下冒落带矸石注浆充填技术的研究及其工程应用。对大颗粒矸石浆体材料流变特性进行了试验测定和分析,选定低于3 mm的大颗粒矸石为主要原料,加水制成浓度为55%~60%的矸石浆体;研究了特厚煤层综放开采采空区的空间规律,运用高压泵送技术将浆体注入井下空间进行充填,具有系统独立、充采平行、安全高效等优势。工程应用表明,该充填技术工艺妥善解决了传统矸石回填处理能力低、影响生产的问题,可为特厚煤层综放开采工艺的矸石处置提供参考。

新景煤矿3111工作面顶板抽采巷可行性分析及其应用研究

以山西新景煤矿3111工作面为例,在Y型通风方式的制约生产衔接的情况下,分析邻近层抽采可行性,并提出巷道优化布置方案,研究结果为高瓦斯矿井和煤瓦斯突出矿井的巷道布置方式提供了启示,对其他具有类似开采条件的矿山具有指导意义。

综放临空开采护巷煤柱应力分布规律及合理宽度研究

为进一步掌握综放工作面临空开采回采巷道煤岩体变形规律及其控制技术、确定合理的煤柱宽度及回采巷道超前支护范围,以某煤矿综放工作面为研究对象,采用理论计算和数值模拟相结合的方法,研究不同尺寸的煤柱内受力情况和裂隙分布以及工作面回采过程中超前支承压力等对巷道的影响情况。确定护巷煤柱宽度为25 m,超前支护范围为91 m。根据分析结果,巷道采用锚网索联合支护,保证了安全生产。

不规则煤柱作用下工作面开采的三维数值模拟

通过对三河尖煤矿9202工作面实际开采情况的模拟,分析了近距离煤层或煤层群开采时,上部煤层开采后遗留的煤柱对下部煤层开采的影响.模拟显示下部煤层工作面推进到煤柱下方时形成的应力集中远大于工作面超前支承压力和煤柱引起的支承压力的简单叠加,形成的高应力区极易引发诸如冲击矿压的矿井灾害;指出在近距离煤层或煤层群开采时,要合理布置工作面的位置,根据上部煤层开采的时空关系来合理布置下部煤层工作面的回采巷道,并尽量避免在煤柱正下方采煤.

近距离孤岛工作面动压影响巷道围岩控制

近距离煤层孤岛工作面上部煤层与下部煤层回采巷道为楼上楼形式时,下部煤层回采巷道的维护十分困难.结合付村矿209孤岛工作面工程地质实际条件,运用三维数值模拟软件FLAC3D,分析了此种情况下,影响下部煤层回采巷道围岩稳定性的主要因素.通过对3上煤层开采影响下3下巷道围岩的位移与应力分析研究,指出孤岛工作面楼上楼巷道围岩极不稳定,在动压影响下极易产生形变,其中水平应力对巷道围岩的影响比垂直应力更大.在此基础上提出了控制巷道围岩的空间斜拉锚索的支护方案.