Formation mechanism and height calculation of the caved zone and water-conducting fracture zone in solid backfill mining

To study the heights of the caved zone and water-conducting fracture zone in backfill mining,the failure mechanism of strata during backfill mining was analyzed,and a method for determining the heights of the two zones was proposed based on key strata theory.The movement and failure regularity of the strata above the backfilling panel were revealed through numerical simulation.Considering the geologic conditions of the CT101 backfilling panel,the height of the fracture zone was determined using the proposed method along with empirical calculation,numerical simulation,and borehole detection.The results of the new calculation method were similar to in situ measurements.The traditional empirical formula,which is based on the equivalent mining height model,resulted in large errors during calculation.The findings indicate the reliability of the new method and demonstrate its significance for creating reference data for related studies.

Technical parameters of drawing and coal-gangue field movements of a fully mechanized large mining height top coal caving working face

Under fully mechanized, large mining height top coal caving conditions, the shield beam slope angle of the support increases due to the enlargement of the top coal breaking and caving space. This results in a change of the caving window location and dimensions and, therefore, the granular coal-gangue movement and flows provide new characteristics during top coal caving. The main inferences we draw are as follows. Firstly, after shifting the supports, the caved top coal layer line and the coal gangue boundary line become steeper and are clearly larger than those under common mining heights. Secondly, during the top coal caving procedure, the speed of the coal-gangue flow increases and at the same drawing interval, the distance between the coal-gangue boundary line and the top beam end is reduced. Thirdly, affected by the drawing ratio, the slope angle of the shield beam and the dimensions of the caving window, it is easy to mix the gangue. A rational drawing interval will cause the coal-gangue boundary line to be slightly behind the down tail boom lower boundary. This rational drawing interval under conditions of large mining heights has been analyzed and determined.

Rational cutting height for large cutting height fully mechanized top-coal caving

Large cutting height fully mechanized top-coal caving is a new mining method that improves recovery ratio and single-pass production. It also allows safe and efficient mining. A rational cutting height is one key parameter of this technique. Numerical simulation and a granular-media model experiment were used to analyze the effect of cutting height on the rock pressure of a fully mechanized top-coal caving work face. The recovery ratio was also studied. As the cutting height increases the top-coal thickness is reduced. Changing the ratio of cutting to drawing height intensifies the face pressure and the top-coal shattering. A maximum cutting height exists under a given set of conditions due to issues with surrounding rock-mass control. An increase in cutting height makes the top-coal cave better and the recovery ratio when drawing top-coal is then improved. A method of adjusting the face rock pressure is presented. Changing the cutting to drawing height ratio is the technique used to control face rock pressure. The recovery ratio when cutting coal exceeds that when caving top-coal so the face recovery ratio may be improved by over sizing the cutting height and increasing the top-coal drawing ratio. An optimum ratio of cutting to drawing height exists that maximizes the face recovery ratio. A rational cutting height is determined by comprehensively considering the surrounding rock-mass control and the recovery ratio. At the same time increasing the cutting height can improve single pass mining during fully mechanized top-coal caving.

Similar material simulation research on movement law of roof over-lying strata in stope of fully mechanized caving face with large mining height

Similar material simulation test W9-15 101 fully mechanized caving face with was carried out in a geological model of large mining height in the Liuhuanggou Colliery, in Xinjiang Uigur Autonomous Region. The roof overlying strata movement law in the stope of a fully mechanized caving face with large mining height was studied and show that the roof overlying strata in the stope of a fully mechanized caving face with large mining height can be formed into a stable arch structure; the fracture rock beam is formed resembling a ＂bond beam＂, but it has essentially the structure of ＂multi-span beams＂ under the big structure of the stable arch. The roof overlying strata movement law in the stope of a fully mechanized caving face with large mining height is similar to that of the common, fully mechanized caving stope, which is determined by the deformation and instability of the structure of ＂multi-span beams＂. But because of the differences between the mining heights, the peak pressure in the stope of a fully mechanized caving face with large mining height is smaller while the affected area of abutment pressure is wider in the front of the working face; this is the obvious difference in abutment pressure between the stope of a fully mechanized caving face with large mining height and that of the common.

厚煤层大采高综放工作面覆岩断裂演化规律研究

大采高综放开采易形成强烈的矿压显现,上覆岩层的断裂演化规律对工作面安全生产至关重要。以羊场湾煤矿160206工作面为工程背景,运用相似模拟试验、数值模拟和理论分析的综合研究方法,对大采高综放工作面覆岩的断裂过程与覆岩运移规律进行系统研究。研究表明:导水裂隙带内岩层随工作面推进表现为“台阶下沉”,同层岩层下沉趋势沿走向表现为“急剧下降—稳定(最大值)—快速上升—稳定(最小值)”。工作面覆岩运动场由两区分布(加速下沉区、缓慢下沉区)演化为三区分布(加速下沉区、缓慢下沉区、稳定区)。对离层演化与地表下沉规律进行了定量描述,运用理论计算表达式深入地剖析了地表的动态下沉机理及其相关因素。结合相似模拟与数值模拟的试验结果,提出了覆岩断裂演化的形态变化特征:覆岩断裂形态由“单等腰梯形”演化为“双等腰梯形”,表土层影响区由“矩形”演化为“倒梯形”。分析了覆岩中垮落区、离层区、压实区、裂隙富集区的动态演化过程:垮落区逐渐增大至一定程度,高度小幅度降低并趋于稳定,离层区由下至上逐渐发育并随工作面向前移动,离层区逐渐闭合形成压实区,且压实区逐渐增大并最终保持稳定,裂隙富集区位于采空区前后端部并随工作面向前移动。

无底柱分段崩落法结构参数的影响因素及计算

分析无底柱分段崩落法的特征及其优缺点,整理了该采矿方法主要结构参数的影响因素,并归纳了主要结构参数的理论计算公式,同时通过尖山采场的室内放矿实验及现场实际效果,对归纳整理的主要结构参数计算公式进行验证。可为采用无底柱分段崩落法的矿山提供设计依据。

6~10 m厚煤层超大采高液压支架及其工作面系统自适应智能耦合控制

厚煤层储量及产量占我国原煤总储量及产量的一半,通过梳理厚煤层开采历史沿革,总结了我国厚煤层开采40年来的技术及装备研发实践,系统分析了以高端大采高液压支架及围岩智能耦合理论为代表的6~10 m大采高综采高效智能化综采技术及装备研究进展,提出了大采高支护理论及围岩智能耦合控制的突破是厚煤层一次开采高度突破的首要因素,完善的感知体系建立是液压支架自适应支护的前提,数字技术的应用为大采高工作面高效推进及装备智能协同控制提供了新的技术途径;阐明了大采高综放液压支架与围岩耦合关系,剖析了采高增加对硬煤层冒放性的有利影响,提出了基于煤矸识别、放煤机构控制的“纯煤段记忆放煤+煤岩分界模糊段人工反馈式干预放煤”的智能放煤控制策略;分析了大采高开采“采–运”协同智能耦合控制关键技术,构建了基于采煤机牵引速度与刮板输送机链速间联动调节的工作面装备间多机异构耦合自适应协同控制模型;研发了厚煤层开采中10 m超大采高液压支架,分析了厚煤层开采不断突破开采高度极限的新认识,从开采装备、控制系统等方面提出厚煤层一次开采高度的突破的研发方向。

自然崩落法拉底参数对矿岩初始与持续崩落的影响机制

矿岩自然崩落过程中初始崩落与持续崩落的作用机制影响崩落时空演化规律。为了研究拉底方向与拉底高度对自然崩落法矿山初始与持续崩落过程的影响,采用FLAC3D数值模拟,开展斑岩型厚大铜矿拉底推进方向垂直或平行于最大主应力方向、拉底高度8~12 m条件下的初始崩落条件、持续崩落条件、崩落体形态、崩落矿量的规律研究。结果表明,累积拉底面积与崩落高度呈二次函数关系;在发生初始崩落后,累积拉底面积与累积崩落矿量呈指数函数关系。当拉底方向一定时,崩落高度随着拉底高度的增大而增大,且拉底高度大时有利于提早诱发初始崩落与持续崩落,累积崩落矿量整体呈增长趋势。拉底方向垂直最大主应力时比平行于最大主应力时更易诱发初始崩落、持续崩落。研究结果揭示了拉底参数对矿岩初始与持续崩落的影响机制,可为硬岩矿山自然崩落法的基础研究提供依据。

金谷煤矿充水因素分析评价及涌水量预测

本文对山西古县金谷煤业有限公司的地质与水文地质条件进行分析研究,查明矿井主要充水因素,包括大气降水及地表水、含水层水、采空区积水等。通过现场实测和数据分析,确定了各含水层的水文特征及其与矿井充水的关系,计算了垮落带和导水裂隙带高度以及奥灰水突水系数。在此基础上,采用面积比拟法对矿井涌水量进行了预测,得出矿井正常涌水量为54.58 m^(3)/h,最大涌水量为81.87 m^(3)/h。这一研究为金谷煤业矿井水害防治提供了科学依据,有助于提高矿井的安全生产水平,对于类似地质条件下的煤矿充水因素评价与涌水量预测具有重要的参考价值。

厚煤层放顶煤开采采高对顶煤破坏性分析

厚煤层放顶煤开采中,开采高度作为重要的工艺参数对顶煤的破坏性具有重要的影响,从而影响煤层的采出率及质量。采用数值分析的形式对不同采高对顶煤的破坏性进行模拟,从而得到合理的采高参数,提高顶煤的破坏性,提高煤矿的开采效率及质量。

袁大滩煤矿超长工作面覆岩两带发育规律研究

针对超长工作面采动影响下覆岩两带发育规律,以袁大滩煤矿工作面为背景,采用理论分析与离散元的3DEC数值计算软件相结合的方法,研究该条件下覆岩裂隙的分布特征与两带发育规律。结果表明,根据理论计算,得到2号煤层工作面不同采高下2种经验公式的两带发育高度,得出随着工作面采高的增加,工作面采后的导水裂隙带高度逐渐增加,但其裂隙高度的递增幅度逐渐减小的规律;通过3DEC数值模拟,11207超长工作面采高每增加0.2 m所得导水裂隙带高度约增加2.01~3.05 m,超长工作面采高越大,开采高度增加引起裂隙发育高度增幅越小。数值模拟与理论计算基本一致且相互印证。工作面实际开采过程中工作面的开采高度逐渐减小,裂隙带发育高度逐渐降低,覆岩位移量逐渐减小,集中应力逐渐减弱,开采初期需要加强监测,增强防护措施。

垮落带和导水裂隙带发育高度实测

在考虑顶板条件进行理论计算的基础上,使用新设备——双端堵水器进行现场实测,利用井下仰上孔分段注水测漏技术方法,更加精确地研究了A煤矿9+10#煤垮落带和导水裂隙带高度发育规律,均达到了较好的效果,为工作面布置与防治水工作提供了重要的参考依据,保证了矿井安全高效生产。

塔山煤矿特厚煤层综放面顶煤冒放性研究

为研究特厚煤层综放工作面顶煤冒放性,结合塔山煤矿10501工作面5号煤层的开采条件,分别从埋深、煤体强度、煤体裂隙发育程度、夹矸强度和厚度、采放比等方面分析了顶煤冒放性的主要影响因素,数值模拟了2号和5号煤层采动对顶煤破碎效果的影响。根据理论分析、数值模拟结果,采取相应措施后,夹矸破碎程度高,顶煤冒放性好,达到了预期工程效果。

大倾角厚煤层开采不同采高与放煤步距的影响分析

大倾角厚煤层是我国面临的重要的煤层开采形态,由于煤层的倾角较大,造成开采难度的增加。采用放顶煤综采过程中,不同的采高及放煤步距对顶煤的放出具有重要的影响作用。针对大倾角厚煤层开采过程中,不同采高及放煤步距对顶煤采出率的影响采用PFC仿真模拟的方式进行分析。建立了不同参数的开采模型,对开采过程进行仿真模拟,得到采高为4 m放煤步距为1.6 m(两采一放)的开采工艺为最佳的开采参数,此时顶煤的采出率最高,且具有较好的操作性。

程潮铁矿崩落法开采对上覆岩体变形的影响研究

针对程潮铁矿开展工程地质调查,采用离散元分析软件UDEC建立其二维地质剖面模型,在假设其上部水平矿房未开采的条件下,模拟了程潮铁矿无底柱分段崩落法开采-480m、-500m相邻分段的过程,研究单一分段及相邻分段开采导致的围岩“冒落带、导水裂隙带”的分布规律及范围,探索程潮铁矿单分段矿房开采时其上覆岩体形成的导水裂隙带高度范围y随采长x的变化函数,分析无底柱分段崩落法不同分段矿房开采对于上覆岩体变形及影响机理,为类似开采技术条件矿山安全生产提供参考。

工作面综放开采工艺研究

为进一步提升综采工作面的生产能力和生产效率,以21051综采工作面为例在对其基本条件及地质条件综合分析的基础上,确定采用放顶煤采煤工艺对其进行开采;然后,基于PFC2D软件对走向长壁放顶煤和倾斜长壁放顶煤两种开采工艺参数对应的采出率和含矸率等指标进行对比,得出对应开采方式下的最佳放煤工艺参数,研究成果可指导该工作面的实际生产。

改流体技术用于中厚急倾斜矿体开采实验研究

采用无底柱分段崩落法开采中厚急倾斜矿体现已在矿山中得到广泛应用,但仍普遍存在矿石损失贫化的问题,至今未得到根本解决。为实现资源与环境协调的绿色开采,以中厚急倾斜矿体开采为研究对象,基于料仓内改流体结构原理,提出了改流体放矿技术。考虑矿体倾角和厚度、分段高度因素的影响,设计了18组改流体放矿和常规截止品位放矿对比实验,研究了三因素对矿石损失贫化的影响。实验结果表明,不同厚度、不同倾角矿体开采中,改流体放矿技术矿石回收率均高于常规截止品位放矿回收率。在相同废石混入率条件下,改流体放矿矿石回收率为69.09%~82.9%,高于常规截止品位放矿12.66%~30.88%。当矿体倾角为60°~85°时,矿石回收率随矿体倾角的增大而提高;当矿体厚度为6~10 m时,改流体放矿技术矿石回收率高于常规截止品位放矿回收率;当分段高度为10~14 m时,矿石回收率随分段高度的增加而提高。同时,研究了改流体放矿技术机理,通过在采场中设置改流体结构和改变改流板的打开与关闭顺序,从而改变矿岩流动路径,可增大矿石流动范围和流动速率,控制矿岩接触,从而减少矿石损失和贫化。研究表明,改流体放矿技术优于常规截止品位放矿技术,有效改善了矿石损失贫化问题,为中厚急倾斜矿体开采时降低损失贫化提供了新的方法。

厚松散层及超薄覆岩条件下放顶煤开采防砂煤柱

为解放厚松散层及超薄覆岩条件下防砂煤柱储量 ,在掌握三隔、四含水文工程地质条件基础上 ,通过井下疏放四含水、合理确定允许放采比以及控制工作面两端覆岩剪切破坏 ,有效实践了“破坏四含、保护三含”的思路。项目自实施以来 ,已成功回采了 4 0多万t煤炭 ,直接经济效益 4 0 0 0多万元。

正演模拟技术在碳酸盐岩溶洞响应特征研究中的应用

在塔里木盆地奥陶系碳酸盐岩储层识别中,"串珠状"反射是十分重要的地震响应特征之一。文中利用波动方程正演模拟技术,设计了不同的溶洞模型,分析了溶洞宽度和高度变化时对"串珠状"响应特征的影响。结果表明:溶洞宽度增加时,"串珠"响应振幅增强,但响应时间长度不变;溶洞高度增加时,"串珠"振幅呈先增大后减小的趋势,且响应时间长度变长。模型正演为进一步研究溶洞的响应机理、溶洞形状与"串珠"特征的关系提供了手段,从而为碳酸盐岩储层的半定量或定量预测提供了依据。

综采导水裂隙带多因素影响指标研究与高度预计

在分析了导水裂隙带发育高度受多种因素影响的前提下,提出了新的参数指标即硬岩岩性比例系数,代替顶板岩层单轴抗压强度,避免了现行规范中坚硬、中硬、软弱、极软弱顶板类型划分时单轴抗压强度统计不确定问题,以及未反映顶板软硬岩层组合结构问题。以39例综采导水裂隙带实测数据为基础,采用多元回归分析,得到综采导水裂隙带高度与煤层采高、硬岩岩性系数、工作面斜长、采深、开采推进速度多因素之间的非线性统计关系式,并用于淮南谢桥矿首采面的导水裂隙带高度预计。