System dynamics model of the support-surrounding rock system in fully mechanized mining with large mining height face and its application

Fully mechanized mining with large mining height(FMMLMH)is widely used in thick coal seam mining face for its higher recovery ratio,especially where the thickness is less than 7.0 m.However,because of the great mining height and intense rock pressure,the coal wall rib spalling,roof falling and the instability of support occur more likely in FMMLMH working face,and the above three types of disasters interact with each other with complicated relationships.In order to get the relationship between each two of coal wall,roof,floor and support,and reduce the occurrence probability of the three types of disasters,we established the system dynamics(SD)model of the support-surrounding rock system which is composed of"coal wall-roof-floor-support"(CW-R-F-S)in a FMMLMH working face based on the condition of No.15104 working face in Sijiazhuang coal mine.With the software of Vensim,we also simulated the interaction process between each two factors of roof,floor,coal wall and the support.The results show that the SD model of"CW-R-F-S"system can reveal the complicated and interactive relationship clearly between the support and surrounding rock in the FMMLMH working face.By increasing the advancing speed of working face,the support resistance or the length of support guard,or by decreasing the tipto-face distance,the stability of"CW-R-F-S"system will be higher and the happening probability of the disasters such as coal wall rib spalling,roof falling or the instability of support will be lower.These research findings have been testified in field application in No.15104 working face,which can provide a new approach for researching the interaction relationship of support and surrounding rock.

Stability mechanism and control of the pumpable supports in longwall recovery room

The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the PPS.Subsequently,the generation mechanisms,and influencing factors of the UBC were revealed.Global sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall PRR.Monitor results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the PPS.Finally,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.

Nonlinear Static and Dynamic Stiffness Characteristics of Support Hydraulic System of TBM

Full-face hard rock tunnel boring machines(TBM)are essential equipment in highway and railway tunnel engineering construction.During the tunneling process,TBM have serious vibrations,which can damage some of its key components.The support system,an important part of TBM,is one path through which vibrational energy from the cutter head is transmitted.To reduce the vibration of support systems of TBM during the excavation process,based on the structural features of the support hydraulic system,a nonlinear dynamical model of support hydraulic systems of TBM is established.The influences of the component structure parameters and operating conditions parameters on the stiffness characteristics of the support hydraulic system are analyzed.The analysis results indicate that the static stiffness of the support hydraulic system consists of an increase stage,stable stage and decrease stage.The static stiffness value increases with an increase in the clearances.The pre-compression length of the spring in the relief valve a ects the range of the stable stage of the static stiffness,and it does not a ect the static stiffness value.The dynamic stiffness of the support hydraulic system consists of a U-shape and reverse U-shape.The bottom value of the U-shape increases with the amplitude and frequency of the external force acting on the cylinder body,however,the top value of the reverse U-shape remains constant.This study instructs how to design the support hydraulic system of TBM.

Analysis and application in controlling surrounding rock of support reinforced roadway in gob-side entry with fully mechanized mining

In order to optimize gob-side entry in fully-mechanized working face in moderate-thick-coal seams, we adopt a new attempt to pack roadside by pumping ordinary concrete, which is very important for the development of gob-side entry technology. The concrete has a long initial setting time and a low initial strength. So it is difficult to control the surrounding rock. In this paper, we analyze the effect of using roadside cable to reinforce supporting in gob-side entry surrounding rock controlling based on elas-tic-plastic and material mechanics knowledge. And then we propose a scheme that cable is used to reinforce roadside supporting and a single hydraulic prop is used as the temporary supporting in gob side. Using the numerical simulation software FLAC2D, we numerically simulated supporting scheme. Results of both the 2D modeling and the industrial test on No.3117 face in Jingang Mine prove that the scheme is feasible. The results show that the technology of protecting the roadway in gob-entry retained efficiently make up the deficiency of roadside packing with ordinary concrete, effectively control the roof strata and acquire a good result of retaining roadway.

Influence of dynamic pressure on deep underground soft rock roadway support and its application

Due to high ground stress and mining disturbance, the deformation and failure of deep soft rock roadway is serious, and invalidation of the anchor net-anchor cable supporting structure occurs. The failure characteristics of roadways revealed with the help of the ground pressure monitoring. Theoretical analysis was adopted to analyze the influence of mining disturbance on stress distribution in surrounding rock,and the change of stress was also calculated. Considering the change of stress in surrounding rock of bottom extraction roadway, the displacement, plastic zone and distribution law of principal stress difference under different support schemes were studied by means of FLAC3D. The supporting scheme of U-shaped steel was proposed for bottom extraction roadway that underwent mining disturbance. We carried out a similarity model test to verify the effect of support in dynamic pressure. Monitoring results demonstrated the change rules of deformation and stress of surrounding rock in different supporting schemes. The supporting scheme of U-shaped steel had an effective control on deformation of surrounding rock. The scheme was successfully applied in underground engineering practice, and achieved good technical and economic benefits.

Surrounding rock control theory and longwall mining technology innovation

To accommodate surrounding rock structure stability control problem in underground mining, we study the coupling effect principle between hydraulic support and surrounding rock, and develop a series of longwall mining technology and equipment, which solves four common technical problems that significantly undermine coal mining safety, efficiency, and high recovery and extraction rates. Based on the coupling characteristic between mining-induced stress field and supporting stress field of hydraulic support, we identify six controllable factors in the application of hydraulic support to surrounding rock, and further reveal the relationship between hydraulic support and surrounding rock in terms of the strength, the stiffness, and the stability coupling. Our findings provide a plausible solution to the longwall mining technical problem with 6-8 m mining height. By analyzing the dynamic disequilibrium characteristics between hydraulic support and surrounding rock, we propose the intelligent top coal caving control method and the high-coal-recovery-rate tech- nology for fully mechanized caving faces. With the invention of this technology, China is likely to lead the world in terms of the fully mechanized top coal caving mining technology. We are also the first to employ the intelligent coupling technology between hydraulic support and surrounding rock, and automated mining mode, and supporting system coop- erative control with automatic organization. We develop the comprehensive multi-index intelligence adjusting height decision-making mechanism and three-dimensional navigation automatic adjusting straightness technology based on shearer cutting height memory association, cutting power parameters, vibration, and video information, leading to the first set of intelligent longwall mining technology and equipment for thin seam. Our innovation makes a solid contribution to the revolution of intelligence mining technology. With the innovative use of three-dimensional coupling control principle for surrounding rock, we successfully resolve the technological difficulties of longwall mining equipment and surrounding rock control for steep dipping seam, making a breakthrough of longwall mining technology with steep dipping seam.

Study on Harnessing of Roadway with Badly Damaged Surrounding Rock

This paper, based on the strain softening character of rock, and the de formation feature of roadway with badly damaged surrounding rock and adopting the ideal elastoplastic softening model, derives the formula for calculating the supporting resistance for the roadway. It is pointed out that controlling the rheid speed of the rock in the plastic softening area is critical and that the combined supporting, i. e. combining surrounding rock internal rein forcement with external supporting f is the reasonahle supporting to this kiud of roadways. The theory and practice introduced in this paper are of universal significance for harnessing the roadway with badly damaged surrounding rock.

迈步式吸能支架-巷道围岩系统动力响应数值分析

为防止吸能支架与冲击地压引起的围岩发生共振,提高巷道支护围岩体系的安全性。采用理论分析和数值模拟方法,建立吸能支架-巷道围岩系统模型,考虑初始应力条件,通过在巷道上方施加简谐激励以模拟动载作用,研究在不同动载频率下吸能支架动力响应规律。研究结果表明:当外界扰动频率接近系统固有频率时,会发生共振现象。动载作用下,吸能支架最大位移发生在顶梁,而顶梁位移分布呈中间大两端小趋势,应力分布呈中间高两边低趋势;靠近顶板和靠近动载源处的围岩的加速度幅值较大。动载频率为吸能支架固有频率时,立柱的振动频率与围岩振动频率相差较小。研究结果为动载作用下巷道围岩控制提供有益参考。

深地煤炭资源安全高效智能化开采关键技术与实践

深地煤炭资源地质赋存复杂,智能化开采是深地资源安全、高效、绿色发展的必由之路。智能化开采成套技术与装备能否适应千米深井复杂地质环境、控制围岩稳定并驱动装备跟随煤层自动推进是影响煤炭安全高效开采、减少作业人员、降低劳动强度的关键。山东能源集团聚焦千米深井智能化开采围岩控制理论,提出了以强度耦合、刚度耦合和稳定性耦合为核心的支架-围岩智能耦合关系,并形成与之相适应的智能耦合控制逻辑;为突破超大采高智能综采开采工艺及超高煤壁围岩控制技术瓶颈,提出了超大采高液压支架工作阻力“双因素控制法”,发明了三滚筒采煤机及其配套开采方法,研制了与超大采高智能综采相匹配的液压支架及配套系统;针对超大采高综放开采智能化放煤理论与围岩控制难题,提出超大采高综放支架-围岩耦合协调采放空间控制方法,创新了超大采高综放“马鞍形”开采工艺,研制了7 m超大采高智能综放开采液压支架及配套系统;研发了无反复支撑、快速循环自移的单元式超前支架,解决了回采巷道超前支护距离长、支护技术与装备适应性差的问题;开发了基于惯导和精准地质模型的智能采煤控制系统,解决了深部矿井工作面设备智能控制及困扰连续生产的难题;搭建了千米深井智能化开采综合管控平台,实现了千米深井重大灾害多源异构数据融合与管控。上述核心技术在山东能源集团赵楼煤矿7302工作面、东滩煤矿3308工作面等多个工作面进行了智能化开采示范建设,取得了良好的应用效果,所获成果整体推动了我国深地煤炭资源安全高效智能化开采水平,可以为类似矿井智能化工作面建设提供理论与技术借鉴。

六柱式充填液压支架动力学模型建立与仿真

目的为研究六柱式充填液压支架在不同外部激励等扰动作用下的动态特性,方法基于拉格朗日方法和广义空间坐标系原理建立六柱式充填液压支架的运动微分方程及状态空间模型。根据支架结构和相关参数,利用MATLAB对系统运动微分方程求解,分析不同扰动频率和扰动幅值对顶梁垂向振动、侧倾和俯仰振动的影响。结果结果表明,支架在外部激励等扰动频率为20 rad/s时,顶梁垂向振动最大振幅约为0.91 mm,顶梁瞬间的俯仰振动波动较大,其最大振幅约为5.5×10^(−3)rad,侧倾振动相对较小,其最大振幅约为4.3×10^(−3)rad;顶梁侧倾振幅略高于俯仰振动,但振动的程度均能保持在可控范围内。当外部激励频率为20~80 rad/s时,随着扰动频率增大,顶梁垂向振动逐渐降低,但降低的幅度趋于平缓,支架侧倾振动程度变化趋势与垂向振动类似,而俯仰振动变化随频率改变不明显。扰动为20~80 rad/s时,顶梁垂向、侧倾和俯仰振动均随着外部激励增加而愈加剧烈,外部激励的大小对顶梁垂向及侧倾振动影响较为显著,而对俯仰振动影响较小。结论研究结果可为六柱式充填液压支架的优化设计及稳定性评价提供一定参考。

动载扰动下特厚煤层巷道破坏机理及其控制技术研究

为改善园子沟煤矿特厚煤层巷道在高应力、强动载扰动下支护效果,以园子沟煤矿1102007工作面为工程背景,通过现场调研测试、数值模拟、理论分析及工程实践的方法,对巷道支护进行优化。通过数值模拟,分析了巷道围岩在动载扰动下变形破坏效应,巷道围岩浅部支护构件易损坏,深部围岩变形破坏严重;通过理论分析,提出了“长短锚杆索梯次支护+帮顶M型钢带整体支护+弱结构构建”组合支护技术。现场实践结果表明,采用新的支护组合体系后,可以有效控制巷道围岩稳定性。

综采工作面大断面切眼围岩稳定控制研究

综采工作面大断面切眼围岩的稳定性是影响综采工作面正常设备安装与回采的关键因素,以小保当一号煤矿112203综采工作面大断面切眼为研究对象,通过理论分析研究了112203综采工作面大断面切眼顶板变形机理及理论支护参数。采用离散元数值模拟软件建立了UDEC Trigon模型,研究了支护强度对二次成巷顶板裂隙演化规律、破坏模式和损伤程度的影响规律。数值模拟结果表明:合理的支护技术能够控制顶板微裂纹的扩展降低宏观裂隙的发育高度。长短锚索联合支护后顶板岩层中存在的岩石桥能够有效的限制宏观裂缝的形成以及它们之间的相互作用,特别是对交界面区域的重点支护能够降低二次成巷顶板裂隙的发育高度,减弱深部大断面切眼顶板岩层的损伤程度。现场试验表明,采用加长锚索以及单体液压支柱的补强支护后,112203综采工作面大断面切眼两帮移近量稳定在350 mm左右,顶底板移近量稳定在550 mm左右,顶板未出现明显离层,最大顶板离层量为2.4 mm。本文的理论分析及数值模拟有助于理解综采工作面大断面切眼顶板破坏模式,同时为其控制技术参数的设计提供了方法。

乌东德水电站导流洞下闸封堵期^(#)5导流洞围岩稳定分析与评价

采用导流洞泄流的水利水电工程,蓄水期需将临时导流洞依次下闸封堵,蓄水后转换成永久泄水建筑物泄流,导流洞下闸封堵期上游水库水位不断提高,导流洞在高水头条件下能否安全下闸封堵,决定着工程能否按期蓄水,发挥工程效益。以金沙江乌东德水电站为例,针对导流洞下闸封堵期^(#)5导流洞围岩稳定与安全,采用三维数值分析方法对Ⅳ_(2)类围岩条件和F_(3)断层条件两种不同地质洞段进行对比分析,系统研究了两种地质洞段下,岩体渗流场、围岩增量变形、围岩应力、围岩塑性区、支护结构受力和衬砌应力;同时,考虑衬砌失效后,该洞段封堵施工期围岩稳定性,评价隧洞支护系统安全状态。结果表明,洞身排水孔排水效果明显,大幅降低了洞周孔隙水压力;洞周围岩整体呈向洞内变形趋势,围岩增量变形较小;围岩应力分布有一定调整,但总体变化不大,塑性区范围基本无扩展;支护系统均处于正常受力状态,断层附近的部分锚杆受力较大;衬砌受力较小,衬砌配筋满足衬砌受力要求,^(#)5导流洞下闸封堵期围岩稳定安全性较好。

超大断面破碎软岩硐室围岩稳定性及控制技术研究

针对超大断面硐室围岩失稳问题,以锦丰金矿地下搅拌站超大断面硐室为研究对象,利用矿山地质钻孔数据库建立矿区岩石质量指标模型,并基于该模型选择搅拌站建设最优位置为150 m中段。通过实验室试验、现场调查及地应力测量确定围岩参数及应力分布特征,利用Phase2岩石力学软件对硐室开挖后的稳定性进行数值模拟分析,根据分析结果并结合工程类比法,提出管缝锚杆+挂网+湿喷混凝土+树脂锚杆+长锚索+壁后注浆+防底鼓反拱混凝土联合支护方案对围岩进行支护。采用数值模拟及现场应用效果监测方法对加固效果进行评价,结果表明:加固后的硐室最大变形量为31 mm,最大主应力为25 MPa,锚杆(索)均未发生破坏,混凝土衬砌所有单元的安全系数均大于1.2,支护结构处于合理有效的受力状态。采用该联合支护方式加固后的硐室处于稳定状态,支护效果良好,相关研究成果对类似工程具有重要借鉴意义。

动压影响区松软留顶煤巷道支护技术研究

厚煤层开采工作面回采巷道断面普遍较大,随着矿井采掘深度和开采范围的不断增大,回采巷道围岩控制难度增加,这就需要做好动压巷道围岩变形控制。本文以某煤矿11307回顺为研究对象,分析动压影响下松软留顶煤巷道围岩变形特征及影响因素,并提出具体支护方案。总体来说,采用锚杆索、注浆、钢筋托梁及金属网组合支护顶板,采用锚杆索、金属网组合支护巷帮。工程应用后,11307回顺巷道位移变形量较小,可满足使用需要。

煤泥岩条件下大断面巷道支护技术研究

针对某矿进风立井硐室群区马头门巷道的支护难题,综合运用现场调研、文献检索、理论分析等研究方法,研究了巷道所处区域的矿压特征和围岩变形破坏特征,分析了该巷道原支护方案的缺陷及应该优化的方向,设计了一套“高预应力锚索整体支护方案”,并成功进行了工程实践。掘进支护后的矿压观测表明,将优化后的支护方案实施后,巷道顶底板移近量、两帮移近量、顶板离层值均得到了有效控制,实现了煤泥岩条件下大断面巷道的有效支护,保障了矿井安全生产。

煤柱回收工作面支护方案及顶板控制效果分析

随着我国对煤炭需求快速增长,煤炭储采比大幅度下降,煤炭保有储量呈现明显降低趋势,作为不可再生资源,煤炭的可持续开采受到严重威胁,对煤柱进行回收是提高回采率和资源利用率的有效办法。以轿子山煤矿9717工作面为研究对象,针对大巷煤柱回收工作面顶板控制问题,运用理论分析与现场实测相结合的方法,结合大巷煤柱回收工作面支架与围岩耦合关系,确定了支架工作阻力,合理进行了工作面液压支架的选型,设计了煤柱回收工作面的顶板控制方案,分析了工作面支护效果,保障煤柱回收工作面的安全回采。研究可为类似地质条件下的煤柱回收工作面回采提供借鉴。

动压影响下软岩巷道围岩控制技术研究

3506回风巷围岩为软岩且巷道受本采面、邻近采面采动压力影响,围岩变形量较大且局部位置支护体系面临失效问题,给巷道后续使用带来较大影响。对回风巷现场条件及围岩变形特征分析基础上,提出采用高强预紧力锚杆(索)+底角锚杆+巷帮锚索方式进行支护,通过高强预紧力锚杆(索)强化顶板及巷帮围岩支护强度,提高支护体系与围岩耦合效果;采用底角锚杆可降低甚至阻隔顶板及巷帮压力对底板影响,提高底板抗底鼓能力;巷帮锚杆可将巷帮应力向深部转移,减少巷帮表面位移量。现场应用后,3506回风巷在动压影响下围岩变形量始终在允许范围内,为巷道正常使用创造良好条件。

深部开采动压巷道切顶护巷技术研究

针对采区轨道大巷在邻近的51301工作面采动影响下出现围岩变形量大、支护难度高等问题,结合现场情况提出综合采用切顶卸压+恒阻锚索补强方式控制采区轨道大巷围岩变形。具体在采区轨道大巷邻近的51301运输巷内布置切顶卸压钻孔,通过深孔爆破方式切断采面顶板与采区轨道大巷顶板间应力传递路径;恒阻锚索对采区轨道大巷顶板、两帮进行补强加固,并与原有支护体系相互配合,实现动压影响巷道围岩变形有效控制。现场应用后,轨道大巷围岩变形量大问题得以较好解决,巷道断面收敛量较小,表明现场采用的围岩支护技术取得较好应用成果。

竹林山煤业大断面松软煤层临空动压巷道支—卸协同控制技术实践

山西阳城阳泰集团竹林山煤业有限公司回采巷道采用双巷布置,沿底板掘进,煤层节理裂隙发育,整体强度低。其中的一条巷道为临空留巷巷道,在本工作面采动影响下,巷道围岩出现大变形,无法满足下一个工作面回采的断面要求,不得不进行扩刷返修。对该矿1406运输顺槽(临空巷道)受采动影响期间围岩大变形机理进行了分析,提出了“高强螺纹钢锚杆+高强锚索+钢筋梯子梁+金属网+水力压裂切顶卸压”为核心的大断面松软煤层临空动压巷道支—卸协同控制方案,并应用于1405运输顺槽围岩控制中。现场的巷道矿压监测结果表明,该方案能够有效控制巷道围岩变形,确保工作面回采期间巷道断面的要求。