Characteristics of Gas Emission at Super-Length Fully-Mechanized Top Coal Caving Face

Characteristics of gas emission at the K8206 working face in the Third mine of the Yangquan Coal Group were investigated. The effects of strata movement,advancing velocity of working face,production capacity of working face and gas extraction capability of strike high-level entry on gas emission at K8206 working face were analyzed. A regression equation,reflecting the relationship between relative gas emission rate and the production capacity of work-ing faces,was established. Another regression equation showing the relationship between the gas emission rate from adjacent layers when the working face was advancing for one metre and advancing velocity was derived. It can be con-cluded that,1) the amount of gas emitted at the K8206 working face is far greater than that of ordinary top coal caving faces with a dip length of 180-190 m; 2) the dynamic process of gas emission from adjacent layers during the initial mining stage is controlled by the movement of key strata; 3) the amount of gas emitted that needs to be forced out by air is greatly affected by the capability of gas extraction; 4) when the advancing velocity is between 3.5-5.5 m/d or when the output is up to 8-12 kt/d,the gas emission from adjacent layers is almost constant.

Study on safe thickness of overlying thin bedrock in fully-mechanized top-coal caving face with thick coal seam

To prevent support crush, the overlying strata safe thickness and its influential elements were studied by the adoption of theoretical analysis, numerical simulation and in-situ measurement. According to the production and geological condition of first face in Sima coal mine, the results indicate that the clay contains large permissible bearing ability and has better arching force. After mining destruction, stable structure is formed in bedrock to ensure face safety. The clay thickness ＆ bedrock thickness are the key influential elements to stable structure. The minimal bedrock thickness is about 40 m to ensure safe mining under loose surface soil condition. When surface soil contains mainly thick clay, it forms steady structure with the composition of thin bedrock, so that it can reduce minimal thickness of bedrock and to ensure safe mining. When clay thickness is 40 m, minimal bedrock thickness is 20 m. When clay thickness is 30 m, minimal bedrock thickness is 30 m. Bearing pressure peak ranges from 5 to 15 m in the front face under thin bedrock condition. The bearing pressure distribution range is 15 m. Main roof break distance is small, and initial weighting of main roof is not distinctive, while first periodic weighting of main roof is quite distinctive.

Back-and-forth mining for hard and thick coal seams—research about the mining technology for fully mechanized caving working face of Datong Mine

The article introduced the key technology, mining process, and back-and-forth mining method for the caving working face of hard-thick coal seams in Datong mine, and researched this innovations process, optimized the systemic design and working face out-play, tried to perfect the caving mining technology of hard-thick coal seams further.

Analysis on distribution law of the abutment pressure of the integrated coal beside the road-in packing for gob-side entry retaining in fully-mechanized caving face

The three-dimensional damage constitutive relationship of coal is established and distribution law of the abutment pressure of the integrated coal beside the road-in packing for gob-side entry retaining in fully-mechanized caving face under the effect of given deformation of the main roof is analyzed by the damage mechanics theory. And the relationship between distribution of the abutment pressure and thickness of coal seam is explored. The presented result is of great theoretical significance and practical value to the study on stability control of the surrounding rock of road-in packing for gob-side entry retaining in fully-mechanized caving face.

Waste-filling in fully-mechanized coal mining and its application

A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes) is described. Industrial tests have proved that by using this technology not only can waste be re-used but also coal resources can be exploited with a higher recovery rate without removing buildings located over the working faces. Two special devices, a hydraulic support and a scraper conveyor, run side-by-side on the same working face to simultaneously realize mining and filling. These are described in detail. The tests allow analysis of rock pressure and ground subsidence when backfilling techniques are employed. These values are compared to those from mining without using backfilling techniques, under the same geological conditions. The concept of equivalent mining height is proposed based on theoretical analysis of rock pressure and ground subsidence. The upper limits of the rock pressure and ground subsidence can be estimated in backfilling mining using this concept along with traditional engineering formulae.

Ground pressure and overlying strata structure for a repeated mining face of residual coal after room and pillar mining

To investigate the abnormal ground pressures and roof control problem in fully mechanized repeated mining of residual coal after room and pillar mining, the roof fracture structural model and mechanical model were developed using numerical simulation and theoretical analysis. The roof fracture characteristics of a repeated mining face were revealed and the ground pressure law and roof supporting condi- tions of the repeated mining face were obtained. The results indicate that when the repeated mining face passes the residual pillars, the sudden instability causes fracturing in the main roof above the old goal and forms an extra-large rock block above the mining face. A relatively stable ＂Voussoir beam＂ structure is formed after the advance fracturing of the main roof. When the repeated mining face passes the old goaf, as the large rock block revolves and touches gangue, the rock block will break secondarily under overburden rock loads. An example calculation was performed involving an integrated mine in Shanxi province, results showed that minimum working resistance values of support determined to be reason- able were respectively 11,412 kN and 10,743 kN when repeated mining face passed through residual pillar and goaf. On-site ground pressure monitoring results indicated that the mechanical model and support resistance calculation were reasonable.

Systematic principles of surrounding rock control in longwall mining within thick coal seams

Effective surrounding rock control is a prerequisite for realizing safe mining in underground coal mines.In the past three decades, longwall top-coal caving mining(LTCC) and single pass large height longwall mining(SPLL) found expanded usage in extracting thick coal seams in China. The two mining methods lead to large void space left behind the working face, which increases the difficulty in ground control.Longwall face failure is a common problem in both LTCC and SPLL mining. Such failure is conventionally attributed to low strength and high fracture intensity of the coal seam. However, the stiffness of main components included in the surrounding rock system also greatly influences longwall face stability.Correspondingly, surrounding rock system is developed for LTCC and SPLL faces in this paper. The conditions for simultaneous balance of roof structure and longwall face are put forward by taking the stiffness of coal seam, roof strata and hydraulic support into account. The safety factor of the longwall face is defined as the ratio between the ultimate bearing capacity and actual load imposed on the coal wall.The influences provided by coal strength, coal stiffness, roof stiffness, and hydraulic support stiffness,as well as the movement of roof structure are analyzed. Finally, the key elements dominating longwall face stability are identified for improving surrounding rock control effectiveness in LTCC and SPLL faces.

Research on Feasibility of Top-Coal Caving Based on Neural Network Technique

Based on the neural network technique, this paper proposes a BP neural network model which integrates geological factors which affect top coal caving in a comprehensive index. The index of top coal caving may be used to forecast the mining cost of working faces, which shows the model’s potential prospect of applications.

综放工作面围岩控制与智能化放煤技术现状及展望

分析了厚及特厚煤层智能化综放工作面围岩控制技术与智能化放顶煤技术发展现状及存在的问题,从巷道围岩高效支护、工作面超前支护、坚硬特厚顶煤冒放性、液压支架位姿监测及智能化放顶煤5个方面提出了工程实际需求。针对综放工作面实现安全、高效、智能化开采存在的技术难题与工程需求,对综放工作面围岩控制技术、智能化放煤技术进行了研究:构建了坚硬特厚煤层顶煤悬臂梁力学模型,研发了提高顶煤冒放性及放出率关键技术,实现了坚硬特厚煤层超大采高综放开采;研发了单元式超前液压支架顶梁可旋转自复位装置,实现了液压支架顶梁根据巷道顶板倾斜角度自动旋转支护,有效提高了单元式超前液压支架对巷道顶底板的适应性;提出了采用巷道支护液压支架替代传统锚网支护结构的思路,具有支护效率高、成本低、节省工作面超前支护等优点;开发了基于立柱与尾梁千斤顶行程的综放液压支架支护姿态监测装置与算法,提高了液压支架支护姿态解算效率与精度;提出了基于透明地质模型、煤量监测装置与煤矸识别装置融合的智能放煤控制方法,可有效解决多夹矸层特厚顶煤智能化放煤技术难题。提出智能地质保障技术、机器视觉精准测量与智能感知技术、综放工作面设备智能精准自适应控制技术、综放工作面数字孪生技术等是智能化综放开采技术与装备的发展趋势。

两次采动影响下小煤柱巷道切顶卸压围岩控制技术

为解决多次采动影响下留小煤柱巷道矿压显现剧烈、围岩变形量大的问题,提出了“切顶卸压+顶、帮锚索补强”联合控制技术。以贾家沟煤矿10115运输巷为工程背景,分析了切顶卸压位置、高度与巷道围岩垂直应力分布的关系,给出切顶卸压关键参数,并研究了留小煤柱巷道在切顶卸压后受两次采动影响下的矿压显现规律。结果表明:切顶卸压后,煤柱上的应力峰值随切顶深度的增加呈指数降低;10115运输巷在邻近工作面一次采动过程中巷道围岩变形依次呈现出无变形、缓慢变形、快速变形和围岩稳定的变化规律,本工作面二次采动过程中巷道围岩变形依次呈现出明显变形和剧烈变形的规律;巷道围岩在受二次采动影响时变形更加剧烈,巷道变形量为一次采动时的3.0~7.5倍。

煤矿大倾角综放工作面采煤参数及采煤工艺优化分析

以A煤矿26514工作面为例,介绍了一种基于有限元分析的煤矿大倾角综放工作面采煤参数及采煤工艺优化方法。该方法根据煤矿大倾角综放工作面参数构建相应的有限元模型,通过有限元模型的分析寻找现有工作面采煤参数与采煤工艺的缺陷,进而以此为基础制定工作面采煤参数与采煤工艺优化方案。研究对大倾角综放工作面的开采具有重要意义。

工作面停采煤柱宽度的确定与实践

燕子山矿采用宽煤柱方式护巷,煤柱宽度约60 m,造成资源的严重浪费。通过对回风巷的受力变化规律进行监测分析,得出工作面回采对巷道压力影响的临界距离为35 m。以此为依据,在综合考虑8210工作面特殊性的基础上,分析得出该工作面最佳停采煤柱宽度为38~45 m。为检验8210工作面煤柱宽度,该矿在回风大巷开展了顶板钻孔窥视工作,检测顶板煤层回采期间和停采后的变化情况,窥视检测结果表明,工作面留设38~45 m煤柱宽度能够保证巷道围岩的稳定性,是安全可靠的。

综放工作面小煤柱沿空掘巷煤柱尺寸留设研究

为合理留设综放工作面沿空掘巷煤柱,以山西某矿E4102-1工作面运输顺槽煤柱留设工程概况为例,通过进行调研分析与进行数值模拟分析,并结合工业性试验,得出窄煤柱沿空掘巷技术目前已相对较成熟,可把煤柱尺寸留设为5 m至8 m之间;通过对几种煤柱尺寸下的巷道围岩破坏状况进行数值模拟分析,得出该工作面巷道留设5 m宽的煤柱时,该巷道矿压不会出现明显显现,巷道变形量相对较小,巷道顶板也相对较稳定,能很好的满足矿井安全生产需求,更好地保障矿井安全生产。

大采高工作面末采深孔预注浆加固技术

针对寺河矿大采高工作面末采期间煤壁片帮冒顶问题,对寺河矿5303工作面超前支承压力分布规律、深孔预注浆加固机理、合理注浆加固时机进行了深入分析,通过优选注浆材料及工艺,提出了超前深孔预注浆、撤架通道预注浆、工作面浅孔注浆耦合加固方案。实践表明,深孔预注浆加固方案的应用效果良好,末采期间煤帮基本保持平整,未出现大范围、大深度的片帮现象,工作面最后15 m仅用3 d时间便顺利回采完成,有效确保了支架回撤期间生产的安全性。

华亭煤矿综放工作面末采阶段柔性网支护效果分析

为确保华亭煤矿综放工作面安全高效回撤,250107-1综放工作面末采阶段采用高强聚酯纤维柔性网代替金属网铺顶。主要介绍柔性网使用前运网、挂网相关准备工作以及柔性网施工工艺,并根据250107-1综放工作面柔性网工程实践,分析柔性网在工作面末采阶段的突出优势与存在的问题,并针对柔性网应用过程中存在的问题,提出优化柔性网尺寸、配合金属网挂网技术、加强放煤与割煤工艺管理的保障技术措施。

综掘面风流智能调控数字孪生系统

针对综掘面风筒出风口参数不能随瓦斯、粉尘的浓度变化动态调节风流状态,不能实现复杂恶劣下矿井物理作业环境和虚拟模型互联互通的智能化煤矿发展的要求,提出基于数字孪生技术的综掘面风流智能化调控方法,建立了风流调控装置的动态虚拟模型。研究了风筒出风口参数调控规则获取、基于长短期记忆网络的瓦斯粉尘浓度预测、基于遗传—反向传播神经网络的风筒出风口参数决策等支持虚拟模型实现动态预警预测、具有自主学习和自主决策功能的关键技术。实验表明,数字孪生系统能够高保真度地再现矿井巷道的作业环境,实现虚实融合、迭代优化和以虚控实的综掘面风流新型调控方式,有效优化瓦斯和粉尘的运移分布,提高煤矿开采作业的智能化水平。

Mating model on production capacity for the system of cutting coal and drawing top-coal in FMMSC

Being a safe and highly-efficient mining method, fully mechanized mining with sublevel caving （FMMSC） was extensively employed in Chinese coal mines with thick seam. In order to make drawing top-coal furthest to parallel work with shearer cutting coal, decrease failure ratio of rear scraper conveyor and increase safe production capacity of equipments, based on production technology, set up the mating model of safe production capacity of equipments for the system of drawing top-coal and shearer cutting coal in coal face with sublevel caving. It is mean capability of drawing top-coal adapted to the capability of shearer cutting coal in a working circle in the coal face that was deduced. The type selection of equipment of rear scraper conveyor can be tackled with this mating model. The model was applied in FMMSC in Yangcun Coal Mine, Yima Coal Group of China. With the mating light-equipments, the coal output in coal face attained 1.05 Mt in 2004. It gained better technical-economic benefit.

巨厚砾岩层下综放工作面冲击地压危险性评价和矿震发生特征分析

为有效监测和防治综采工作面冲击地压事故,以耿村煤矿巨厚砾岩层下综放工作面为工程背景,采用综合指数法评价综放工作面冲击地压危险性,利用微震监测结果研究综放工作面回采期间矿震特征。结果表明:(1)13230综放工作面冲击危险性指数为0.65,属于中等冲击地压类型;(2)综放工作面回采期间矿震主要发生在工作面前方顶底板煤岩体中,工作面处于“见方区”时发生矿震的频次、最大能量和总能量均明显高于“非见方区”的,“见方区”矿震的震源主要位于工作面前方中部顶底板煤岩体和运输平巷上帮顶板煤岩体中;(3)综放工作面顶板周期来压期间通常伴随大能量的矿震事件。研究结果可为耿村煤矿综放开采冲击地压监测和防治提供参考。

综放工作面转采技术参数设计研究

为实现唐山矿Y394综采放顶煤工作面转采过程中安全高效生产,基于工作面实际地质条件,将转采过程划分为“缩面+转面”两个阶段,有效消除了工作面撤支架工序与工作面旋转工序的交叉影响。缩面阶段工作面长度由132 m缩短至125 m,支架不旋转方向,数量由93架降低至86架。转面阶段工作面长度先由125 m缩短为120 m,之后伸长至122 m,支架数保持86架,工作面旋转角度23°,转面循环角度2°,共12次转面循环。工作面进入缩面区后,运输巷侧应力上升幅度高于回风巷。工作面进入转面区后,运输巷侧应力整体大于14.5 MPa,回风巷侧整体应力大于13.4 MPa,回风巷侧单体柱与工作面距离不变时应力仍呈上升趋势。采用设计的转采工艺后,Y394综放工作面实现了安全高效生产。

保德煤矿智能综放工作面建设关键技术研究

针对现有智能综放工作面建设的研究成果缺乏某个综放工作面系统化建设实施研究的问题,以国家能源集团神东煤炭集团有限责任公司保德煤矿81309智能综放工作面为研究背景,在液压支架电液控制系统及综采自动化系统配置的基础上,详细介绍了设备升级改造、有限透明开采模型构建、智能放煤工艺决策、煤矸识别方法优化、多模式融合集成控制等关键技术。①对采煤机电控系统进行国产化升级改造,加装惯导系统,配套光纤复合电缆/5G通信,实现采煤机姿态及控制数据高效稳定传输。采用迈步自移设备列车系统并配套管缆伸缩装置,实现设备列车拉移由1~2人完成。②对智能规划中心数据源中的地质模型进行迭代修正,经过一系列换算和多源异构数据融合,形成有限透明开采地质模型。③针对81309工作面一刀一放2轮顺序放煤方式,构建了10个智能综放回采阶段并设计了对应的采煤机、综放液压支架、前后刮板输送机的动作和时间,实现了中部跟机自动化采放、三角煤区域自动开采。④采用振动煤矸识别与视频煤矸识别相结合的方式,建成智能综放煤矸识别系统。⑤以SAM型综采自动化控制系统为枢纽,通过整合液压支架电液控制、视频监控、采煤机电控、三机泵站集控,构建出智能化集中控制系统,初步建成基于透明开采的“采−支−识−放−运”各环节自适应的综放开采工作面。调试结果表明,81309综放工作面中部实现单班自动控制割煤4刀,液压支架实现自动跟机拉架、联动收伸护帮/伸缩梁、自主推溜等功能,智能化集中控制系统可一键启停生产系统,对设备运行数据进行实时监控。