Deformation and failure of a high-steep slope induced by multi-layer coal mining

During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines.Numerical simulation based on discrete element theory can be used to explore the characteristics and mechanism of action of deformation and failure of a slope under complex geological and multi-layer mining conditions.By utilising PFC2 D(particle flow code) software,the deformation and failure characteristics of a high-steep slope in Faer Coal Mine in Guizhou Province,China were investigated.Additionally,the mechanism of influence of different numbers of mining layers on the deformation and failure of the high and steep slope was elucidated.The result showed that after the goaf passed by the slope toe,multi-layer mining aggravated the subsidence and deformation of the slope toe:the slope toppled forward as it sank.The toppling of the slope changed the slope structures:the strata in the front of the slope were transformed from anti-dip to down-dip features.Extruded by collapsedtoppled rock mass,the slope toe and the rock mass located in the lower part of the slope toe generally exhibited a locking effect on the slope.Multi-layer mining degraded the overall stability of the slope,in that the total displacement of the slope was much greater than the total mining thickness of the coal seams.Based on the aforementioned research,ideas for preventing and controlling geological disasters during mining operations under a high-steep slope were proposed.

Comparative study of mining methods for reserves beneath end slope in flat surface mines with ultra-thick coal seams

The paper aims to identify a reasonable method for mining ultra-thick coal seams in an end-slope in surface mine, With a case study of Heidaigou surface coal mine(HSCM), the paper conducted a comparative research on three mining methods, namely Underground Mining Method(UMM), Highwall Mining System(HMS) and Local Steep Slope Mining Method(LSSMM). A model was firstly established to simulate the impact that UMM and HMS exert on monitoring points and surface deformation. The way that stripping and excavation amount varies with different slope angle, and the corresponding end slope stability were analyzed in the mode of LSSMM. Then a TOPSIS model was established by taking into account six indicators such as recovery ratio, technical complexity and adaptability, the impact on surface mining production, production safety and economic benefits. Finally, LSSMM was determined as the best mining method for mining ultra-thick coal seams in end slope in HSCM.

Subsidence control method by inversely-inclined slicing and upward mining for ultra-thick steep seams

Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation.A subsidence control method by inversely-inclined slicing and upward mining is proposed in this paper.By this method,the sequence of collapse of overlying strata and the direction of propagation of strata movement are changed,the extent of roof-side deformation thereby is lessened,and boundary angle of roof-side subsidence is reduced by 5°-10°.The mechanism of this mining method for control of strata movement has been evidenced by numerical simulation and experiments with similarity materials.A subsidence prediction model based on the variation of mining influence propagation angle can be used to evaluate the surface movement and deformation of the mining method.The application of the method in No.3 Mine in Yaojie mining area has yielded the expected result.

Quantitative analysis of biotechnical reinforcement for a steep slope consisting of composite coal-gangue-soil medium adjacent to a mined-out area

The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vegetation and porous characteristics of the soil and rock mass, the steep slope will be destabilized and induce mud-rock flow or derive hazard easily. Firstly, based on the classical slope reinforcement theory, some regularity between the shear and displacement in the destabilized zone of the slope with or without root strength contribution is presented. Then, based on the experimental and statistical analysis of root strength, hydrological characteristics and stability status, etc., some possible biotechnical techniques for reinforcement of the steep slope have been suggested. These methods are important for quantitative analysis of destabilization of the slope and design of the biotechnical reinforcement.

Stability analysis of new safety cleaning bank in steep slope mining

Based on the study of the slope with gently granular structure in Xingqiao open mine, a new safety cleaning bank mode for steep slope mining was developed, including setting up dint cut, and forming natural retaining wall based on the character of gentle incline slope. It can effectively eliminate the impact of sliding body on the bottom working place and slope body, reduce the dilution of ore, keep rainwater from upper steps away, decrease influence of the weak intermediate layer, and cut cost of disposal waste rock. The safety and reliability of the mode were analyzed and verified from 3 aspects: static load calculation, ANSYS simulation of dynamic loading and spot experiment. The result of static loading calculation shows that the retaining wall can support accumulation and extrusion of granular body, and the glide or overturn disaster will not take place. The simulations of dynamic loading show that the retaining wall remains stable until sliding body collapses from 360 m (10 sublevels). Only one new safety cleaning bank in each 15 sublevels can fully meet the need of engineering. The new mode sustains steep slope (mining,) increases the angle of ultimate slope, and reduces invalid overburden amount of rock by 3%5%. The result of spot experiment has verified the exactness of the above calculations and simulations.

Feasibility analysis of gob-side entry retaining on a working face in a steep coal seam

Based on the decline in exploitation of coal resources, steep coal seam mining and mining face tensions continue to explore the feasibility analysis of steeply inclined faces in the gob. One of the key factors in utilizing the technology of gob-side entry retaining in steep coal seams is to safely and effectively prevent caving rock blocks from rushing into the gob-side entry by sliding downwards along levels. Using theoretical analysis and field methods, we numerically simulated the mining process on a fully-mechanized face in a steep coal seam. The stress and deformation process of roof strata has been analyzed, and the difficulty of utilizing the technology is considered and combined with practice in a steep working face in Lvshuidong mine. The feasibility of utilizing the technology of gob-side entry retaining in a steep coal seam has been recognised. We propose that roadways along the left lane offshoot body use a speciallymade reinforced steel dense net to build a dense rock face at the lower head. The results show that the lane offshoot branch creates effective roof control, safe conditions for roadway construction workers, and practical application of steeply inclined gob.

露天矿高陡复杂边坡软弱岩层组“坐落-滑移式”破坏模式研究

边坡稳定性问题随露天矿开采的进行不断突出,而边坡软弱岩层严重影响边坡稳定性。大量工程实例显示,露天矿含软弱岩层组的高陡复杂边坡失稳模式通常为“坐落-滑移式”破坏。为明晰露天矿高陡复杂边坡软弱岩层组“坐落-滑移式”破坏模式的破坏机理,以某露天矿为例,提出一种针对露天矿含软弱岩层组高陡复杂边坡的综合分析方法。研究结果表明:采用工程地质分析、传统极限平衡方法和数值模拟分析相结合的综合分析方法,针对该类型复杂边坡可发挥不同分析方法的优势,较全面地从地质自然环境条件、定性定量方面、应力应变角度分析边坡破坏机理及模式,总结归纳出含软弱层组露天矿高陡复杂边坡“坐落-滑移式”破坏的“坐落-滑移-剪出”三段式破坏特征,为其他类似复杂边坡稳定性的分析和防治提供思路和手段。

基于离散元方法的急倾斜极薄矿脉机械化开采爆破参数仿真优化

急倾斜极薄矿脉留矿法开采爆破空间规整平齐是实现小型采矿机器人高效通行和稳定作业的关键因素。为了提高狭小空间爆破光面控制效果,采用离散元方法和黏结颗粒模型耦合仿真方法,开展了不同炮孔参数条件下急倾斜极薄矿脉爆破模拟,以爆破空间轮廓规整性系数为评价指标,对急倾斜极薄矿脉炮孔布置方式和参数进行了优化。研究结果表明:同等排距和孔距条件下,矩形方式布孔的爆破规整性系数最高,矩形+间隔空孔布孔方式爆破规整性系数次之,之字形炮孔布置方式爆破效果最差;结合爆破经济性指标和采场断面规整性系数综合考虑,对于急倾斜极薄矿脉机械化开采,推荐采用矩形+间隔空孔装药的爆破方式,炮孔排距0.4 m,孔距0.8 m。

急倾斜中厚煤层单一巷道放顶煤采煤方法研究与应用

为解决某矿急倾斜中厚煤层倾角及厚度变化大的开采问题,提出了“急倾斜中厚煤层单一巷道放顶煤采煤方法”。该采煤方法是沿急倾斜煤层倾斜方向划分为若干区段,每个区段沿急倾斜煤层走向仅布置1条巷道。此巷道服务于1个采煤区段,担负工作面通风、运输和行人等任务。对单一巷道放顶煤采煤方法的巷道布置、综放工艺和沿空留巷方法进行了探讨。实践表明,该采煤方法使采煤工作面形成全负压通风,避免了巷道与采空区窜风,杜绝了采空区瓦斯积聚和遗煤自燃,实现了采煤机械化,提高了急倾斜中厚煤层的开采效率和煤炭回收率。单一巷道放顶煤采煤法为类似急倾斜煤层安全、高效开采提供了技术支撑。

红沙泉露天矿工作帮陡帮开采方案研究

工作帮坡角大小直接影响剥离量和生产剥采比的大小,增大工作帮坡角可以减少超前剥离量,降低生产剥采比,节省运距,降低生产成本。但在提高工作帮坡角的同时,需要注意露天矿“二量”,保证露天矿能够持续稳定地生产。以红沙泉露天煤矿为工程背景,研究工作帮坡角与超前剥离量、生产剥采比的变化关系,并结合现场生产实际条件,提出实现工作帮陡帮开采方案。结果表明:工作帮坡角每增加2°,减少超前剥离量4.84 Mm^(3),生产剥采比降低0.22 m^(3)/t;确定将剥离台阶两两组合时,工作帮坡角提高至12°,生产剥采比可降低至2.7 m^(3)/t,同时保证露天矿“二量”要求。

急倾斜中厚矿体开采引发的岩体移动规律模拟实验

急倾斜中厚矿体开采过程中,不同采深下崩落区开采引起的周边岩体移动趋势对诱导冒落法的安全使用起到至关重要的作用。以双鸭山铁矿诱导冒落法开采为工程背景,采用相似材料实验方法模拟了400、600、800、1000 m采深下,矿体及近矿上、下盘围岩受开采扰动的影响。研究表明:400~1000 m采深条件下,矿体及近矿上、下盘围岩均呈现压密→滑移→压密的现象,且放矿对顶板矿岩受扰动的影响较大;矿体水平位移变化相较于近矿上、下盘围岩位移变化更剧烈,同时上盘围岩较下盘围岩对放矿的扰动更敏感;随采深的增加,矿体及近矿上、下盘围岩水平位移和垂直位移均出现由指向采空区转变为背离采空区的现象,且矿体总位移和应变波动范围均增大。

渭南市历史遗留废弃矿山高陡立面生态修复的现状问题与对策探索

针对渭南市废弃矿山生态修复工作在高陡立面生态治理方面,面临的植生层附着难、生境再造难、植被成活难等难题,选取典型矿山高陡立面为试点,采用全国建筑行业科技成果推广认证、国家火炬计划推广认证和北京市新技术新产品(服务)认证的3S-OER植被生态修复技术,探索“抗蚀防护技术”和“3S-OER植被生态防护技术”相结合的高陡立面生态修复新技术、新模式,通过新技术试点矿山的适应性研究和初步治理成效总结,为渭南市及同类型地区矿山高陡立面生态修复工作提供实践经验,对进一步指导和推进矿山高陡立面生态修复工作具有重要意义。

露天矿陡帮开采工艺分析

在当今的岩矿露天开采作业中,陡帮开采是一项重要的工艺措施。为实现此项开采工艺的合理应用,本文特以福建省漳州市华安县水空矿区露天陡帮开采项目为例,对其露天开采过程中的陡帮开采工艺应用进行分析,包括凿岩设备选择、爆破技术应用、铲装技术应用以及防洪排水技术应用等。希望通过本次的分析,可以为陡帮开采工艺的应用与岩矿露天开采质量的提升提供一定参考。

金属露天矿山高陡顺倾边坡稳定性分析研究

金属露天矿山高陡顺倾边坡易形成大规模变形体或大型滑坡,防治难度大,是矿山安全高效生产的重大隐患。本文通过系统开展滇西北衙金多金属矿区万硐山矿段露天采场顺层边坡稳定性分析实例,研究了不同计算方法和不同工况下该类边坡滑坡失稳条件,采用数值模拟计算分析相结合的方法得出其滑坡类型及失稳模式,并提出了这类结构的露天矿山边坡风险管控措施建议,为矿山后续开采提供依据,指导矿山实际生产。

砖瓦用黏土矿历史遗留废弃矿山边坡治理浅析

内蒙古呼和浩特市和林格尔县是构建我国北方生态安全屏障的重要组成部分。为系统解决该地区历史遗留废弃矿山以往矿山开采过程中所引发的崩塌、滑坡等一系列地质灾害问题,提升区域生态系统质量,选用削坡垫坡工程对和林格尔县某区域21处砖瓦用黏土矿历史遗留废弃矿山图斑的高陡边坡进行治理。在对项目区内各边坡实际情况进行具体分析后,通过公式计算出是否需要削垫坡及削垫坡范围,采用南方CASS11软件DTM三角网两期土方法精确计算土(石)方量。此治理工程可最大程度上消除地质灾害隐患且使治理后边坡与周边原始地形相协调,为内蒙古地区其他历史遗留废弃矿山边坡治理工程提供方法和经验。

综合监测手段对露天高陡边坡局部垮塌的分析研究

本文通过对福建省上杭县紫金山金铜矿露天采场东帮进行综合监测,结合边坡雷达预警数据、GNSS监测数据、内部位移计监测数据,分析因降雨引起的采场东北帮820~868边坡在重力及雨水冲刷的双重作用下突破临界约束而出现的突然性垮塌。边坡雷达有监测到位移加速变形的趋势,但未及时发出预警。利用综合监测手段,更进一步准确分析高陡边坡。为解决边坡雷达预警问题更进一步监测边坡局部垮塌变形,本文设置预警分区,对采场东北帮820~868边坡进行区域圈定,设置更为敏感的预警阈值。减小圈定区域边坡雷达监测黄色预警和红色预警的短期预警值、长期预警值和预警面积,对曾经出现垮塌区域设置预警分区,从而做出更加准确的预警,显示监测数据波动变化的趋势,为类似高陡露天边坡监测提供参考。

高陡露天矿山基建高效施工方法的实践

针对露天矿山在基建中面临地形陡峭、削顶高度大、红线控制、施工进度、安全管理、绿色环保等要求,提出采用具有针对性的矿山基建道路、削顶施工方法,即“分层分区、控制爆破、开挖顺序、安全防护”的施工方法,达到安全可控、进度超前、节约成本及周边环境影响小等成效。

复杂环境下超浅埋地铁隧道施工技术研究

地铁隧道建设已成为我国当前社会发展的重要组成部分,在很多城市中都扮演着越来越重要的角色。南京地铁7号线马家园车辆出入段区间线路下穿铁路咽喉区,具有超浅埋、大下坡、小净距的工程特点,同时存在施工难度大、安全风险高的问题。文章以该工程项目为背景,提出了矿山法、盾构法与明挖法相结合的多工法组合方案,并着重对盾构法施工技术开展了重难点分析。在此基础上,针对性地提出了相应的解决方案,为今后类似工程提供参考。

露天石灰岩矿山高陡岩质边坡治理

因不规范开采形成的高陡边坡,易引发滑坡、坍塌等地质灾害,给矿山安全稳定带来极大影响。文章以溧阳某采石灰岩矿山为例,分析了该矿山地质环境条件,探讨了高陡岩质边坡整治及生态修复策略,希望可以为类似边坡治理提供借鉴。

石洞沟煤矿31111急倾斜智能化综采面过构造带加固技术研究与应用

石洞沟煤矿31111急倾斜智能化综采工作面在开采前就对该工作面地质条件进行了分析和研究。在采掘工作中,发现31111回风巷、运输巷存在四个逆断层。针对工作面倾角和采高频繁变化的特点,提出了穿越构造带提前打孔注浆加固技术的研究与实验。为急倾斜大采高智能化综采工作面设备配套选型提供了技术支撑和方向定位。