Support-surrounding rock relationship and top-coal movement laws in large dip angle fully-mechanized caving face

When mining the fully-mechanized longwall caving face along strike, the unstable equipment, the low top-coal recovery ratio and the difficulty in controlling surrounding rock may occur due to large dip angle. Considering the effects of strike angle on support stability, the ‘‘support-surrounding rock"mechanical models of support topple and support slip were established in this paper. On the basis, the influencing factors of support stability were analyzed and the technical measures of controlling support and surrounding rock stability were put forward. Then the loose particles simulation experiment was conducted to analyze the impacts of caving directions and methods on the top-coal recovery in large dip angle fully-mechanized caving face. Finally, the ‘‘upward sequence and double-openings doublerounds" caving technology was determined. The research results are of great scientific significance and practical values to improve large dip thick seam mining technology.

Numerical simulation for determining three zones in the goaf at a fully-mechanized coal face

According to the theory of ventilation network, a model for a filtration flow field in goaf was built and simulation soft- ware for determining the three zones in goaf has been developed. This software uses no-gap-connection between Visual Basic (VB) and Excel to exchange data, uses Component Object Model (COM) component of MATLAB to plot charts of the three zones and to export the corresponding coordinates of the isolines. An example shows that this software is convenient and simple. By using it, the three zones can be easily determined. The software is convenient in studies and analyses of the three zones in goaf.

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.

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.

Patterns governing distribution of surrounding-rock stress and strata behaviors of fully-mechanized caving faces

By employing numerical modeling, similar material simulation and comprehen-sive field observation, investigations were made and patterns were obtained governing surrounding-rock stress distribution and strata behaviors. It shows that patterns governing displacement of FMC roadway surrounding rocks and those governing deformation of supports are basically the same along the strike, but the displacements vary greatly. The front stresses affect greater areas than the lateral stresses and their limit widths of equilib-rium zones and K are almost similar. The stress transmits very deep. Our findings offer scientific basis on which to determine parameters for coal pillar retaining and for roadway out-laying, thus increasing the recovery ratio and improving the maintenance of roadway.

Analysis of Noise at Coal Face by Fully-Mechanized Coal Winning Technology

The noise level of coal face by full-mechanized coal winning technology was measured in a coal mine. And then it was analyzed and evaluated using environment science, ergonomics and fussy mathematics analysis. Basis of the statistics and analysis of the measured noise level some measures, such as applying the new materials and improving the construction of the equipment, were carried out. The resuts show that they can reduce the noise level, improve the working environment and enhance the work efficiency.

Study on gob-side entry retaining in fully-mechanized longwall with top-coal caving and its application

Based on the engineering background of gob-side entry retaining in fully-mechanized longwall with top coal caving(GER-FLTC) on N2105 working face of Yuwu coal mine, by adopting the methods of theoretical analysis and numerical calculation, the control techniques of surrounding rocks in GER-FLTC working face are studied in this paper. The two main difficulties of stability of surrounding rocks at gob-side retained entry in fully-mechanized longwall working face are the stability control of top coal and control of large deformation of GER-FLTC working face. Interaction mechanical model between roofing and roadside backfilling in GER-FLTC is established and the equations for the calculation of roof-cutting resistance of roadside backfilling are derived. Results of numerical calculation show that the damage zones of top coal can be categorized into the delaminating zone of top coal above the backfilling, tensile damage zone of top coal above the retained roadway and shear damage zone of the upper rib of the solid coal. Stability control of top coal is the critical part to success of GER-FLTC. With consideration of large deformation of surrounding rocks of gob-side retained entry in fully-mechanized longwall, the support technique of‘‘roofing control and wall strengthening'' is proposed where high strength and highly prestressed anchor rods and diagonal tensile anchor cables support are used for top coal, high strength and highly prestressed yielding anchor rod support is used for solid coal and roadside prestressed load-carrying backfilling is constructed by high-water material, in order to maintain the integrity of the top coal, transfer load, high resistance yielding load-carrying of solid coal, roof-cutting of roadside backfilling and support,and to achieve GER-FLTC. Results from this study are successfully applied in engineering practice.

SAFETY PROBLEMS IN FULLY-MECHANIZED TOP-COAL CAVING LONGWALL FACES

The thick-san top-ctal catrig technology has been in use in China for over a decade,and has given rise to siguscant economic efficiendes. Eftorts in reeent years to extend its applica tion to more complex mining conditions, mostly high-gas seams , with or without proneness ofspontaneous combustion. have brought about new safety problems This paper will highlight thefcatures and problems retared with thick-seam top-coal caving systems, compared with conventionai, fully-mecbanized longwall systems , particularly issues retated to methane, spontaneous combustion and dust,and disam the methods and measures to ded with them.

Mechanical analysis on deformation of surrounding rock with road-in packing of gob-side entry retaining in fully-mechanized sub-level caving face

Based on the movement regularity of surrounding rock with road-in packing of gob-side entry retaining in fully-mechanized sub-level caving face(RPGERFCF),the me- chanical model of its surrounding rock was established and the calculating formulas of the deformation of the roof,coal wall and filling body were attained.By the mechanical analy- sis to the deformation of the surrounding rock of RPGERFCF,the major factors influencing the deformation of the surrounding rock were found out and the technologic approaches reduced the deformation and enhanced the stability of the surrounding rock were put for- ward.Consequently,the scientific bases were provided for the stability control of the sur- rounding rock of RPGERFCF.

Reliability Analysis of Production System of Fully-Mechanized Face Based on Output Statistic

Production system of fully-mechanized face is a complicated system composed of human, machine and environment, meantime influenced by various random factors. Analyzing the reliability of system needs plentiful data by means of system faults statistic. Based on the viewpoint that shift output of fully-mechanized face is the result of various random factors’ synthetical influence, the process of how to analyze its reliability was deduced by using probability theory, symbolic statistics theory and systematic reliability theory combined with the concrete case study in this paper. And it has been proved that this method is feasible and valuable.

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.

Analysis and control of hydraulic support stability in fully-mechanized longwall face to the dip with great mining height

The working condition of the hydraulic support in working face can be divided into three kinds of situations in the following： roof fall and col,lapse with cavity, advancing support and supporting. Took single support with four-pole in Iongwall face to the dip as research object, control method was studied to avoid support instability in three situations mentioned above. Based on these researches, the major factors of influencing on support stability and its controlling measures were put forward. According to specific conditions of working face 1215（3）, which is fully-mechanized and Iongwall face to the dip with great mining height in Zhangji Coal Mine, Huainan Mining Group, the effective measures was taken to control supports stability..

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.

深部构造区大倾角工作面回撤致冲机理及防治技术

深部构造区大倾角工作面回撤期间冲击风险较高,为研究回撤期间致冲机理及防治技术,以潘西煤矿6199工作面为背景,采用理论分析、数值模拟,结合现场数据开展研究。结果表明:工作面受多因素影响处于复杂高静载环境,上部基本顶尖角区剪应力集中明显,工作面液压支架撤离,上覆岩层压力向工作面前方转移,局部超过极限载荷可能发生高静载加载型冲击,基本顶破断及断层活化产生动载,可能诱发动静载叠加型冲击;根据回撤前矿压数据,前方岩层活动较为剧烈,工作面微震预警事件发生前后支架阻力升高,存在基本顶破断及断层活化可能,冲击风险较高。基于回撤致冲机理提出卸压-支护协同防冲技术,即通过弱化高静载影响,降低动载产生可能性,辅助提高顺槽支护强度、控制工作面顶板降低回撤期间冲击风险;工作面回撤期间矿压监测数据无明显升高,卸压-支护协同防冲技术效果较好。

智采工作面三机数字孪生驱动控制架构

为了进一步提高煤矿综采设备智能控制水平,实现智采工作面常态化运行,提出基于数字孪生智采工作面驱动控制的相关概念和系统架构。智采工作面数字孪生系统由物理设备、虚拟孪生体、虚实交互模型组成,通过数字化方法建立与实体设备相映射的虚拟模型,来达到综采设备在作业过程中虚实交互、智能决策、精准控制和动态演化的目的。阐述智采工作面常态化运行要求和采煤机、液压支架和刮板输送机的相关控制难点。提出了智采工作面单机数字孪生驱动控制架构,包括机理模型、控制模型、孪生数据模型和数字孪生模型同步与演化等要素;研究数字孪生虚实交互方法,利用信息物理系统来保障信息交互能力,采用知识模型来解决数据拥堵问题,为智采工作面数字孪生控制系统的虚实交互提供实时性。提出智采工作面数字孪生驱动的三机协同控制方法,包括三机关联关系、智能采煤控制、智能支护控制与智能运输控制。最后以矿山数字孪生实际应用为例,通过建立相关模型和设计相关实验方案,对数字孪生智能控制进行验证。通过展开数字孪生智能控制架构、模式等理论研究,旨在解决目前综采工作面存在的环境感知程度低、设备预测精度差和人工干预强度大等问题,实现在复杂环境条件下设备的自适应控制与人机交互,为煤矿智能化建设提供借鉴意义。

综掘工作面通风除尘系统结构优化及参数智能调控

针对传统长压短抽式通风除尘系统易形成涡流和风流死角的问题,结合康达效应对长压短抽式通风除尘系统进行结构优化,将抽风管与压风管进行嵌套处理,使负压风筒中的风流在抽风筒管口产生康达效应,确保气流紧贴巷道壁面,减少了空气中粉尘的扩散,并显著降低了能耗。通过流场和离散相模型(DPM)仿真得到最佳压抽比为2∶3,在最佳压抽比下的仿真结果显示,与传统长压短抽式通风除尘系统相比,优化系统除尘后司机处及下风侧的粉尘浓度分别降低了5.56%和55.41%。确定通风除尘系统整体结构及压抽比后,通过参数调控可进一步提高除尘效率。选择风筒与产尘面的距离、风筒中轴线与地面的距离及抽压风筒之间的距离作为通风除尘系统的优化调控参数,通过卷积神经网络(CNN)对优化通风除尘系统的除尘参数进行智能调控,匹配出不同初始粉尘浓度下的最优参数,实现智能除尘。通过等比例缩小的通风除尘实验平台对45组参数调控方案进行实验,结果表明:对比BP神经网络,采用CNN模型进行粉尘浓度预测的准确性和稳定性更优;司机处和下风侧初始粉尘浓度为300~900 mg/m^(3)时,采用优化通风除尘系统后,平均粉尘浓度分别下降了51.49%~83.88%,验证了参数调控的有效性。

智能化采煤工作面建设关键技术运用探究

智能化采煤工作面的建设活动涉及较多内容,需引进多元化的技术指标和方案,提高管理水平。在该环节,相关单位需引进智能感知与监测技术,实时把控智能化采煤工作面的状态,并且结合直线度控制和水平度控制技术,提升采煤工作面的稳定性。另外,还需要引进自适应调高技术,灵活把控采煤机的位置状态,提升采煤活动的灵活性和适应性。此外,还应当结合无人化技术、人工智能、大数据技术,大幅度提高智能化采煤工作面的信息化运作水平,以提高采煤效率和安全性。

基于沿空留巷技术的工作面过陷落柱工程实践

矿井采掘工作揭露陷落柱等地质构造时,往往会带来较多潜在隐患,可能导通含水层、造成瓦斯超限和形成支护难题等。针对6102工作面揭露大型陷落柱影响区的技术难题,矿方根据陷落柱产状及潜在的隐患情况,结合矿井较成熟的沿空留巷理论及经验,成功实施了基于沿空留巷技术的过陷落柱工程实践,在损失一定保护煤柱的代价下,确保了工作面安全快速跳过陷落柱影响区域,沿空留巷技术优势得到验证。

大采高综采面粉尘分布规律及防治技术研究

为研究采煤作业时综采工作面各作业地点粉尘浓度分布规律,以红柳林煤矿25210综采工作面为研究对象,在25210综采工作面正常作业时,对采煤机下风侧、液压支架行人侧、主运输巷及回风巷等采煤区域各测点的全尘和呼尘浓度进行测试,研究采煤作业时各区域粉尘浓度占比以及呼尘占全尘比例,明确不同区域粉尘危害程度;基于现场粉尘浓度分布特征分析,提出针对不同区域粉尘的有效防治方法。结果表明:采煤机下风方向30 m范围内粉尘浓度仍超过200 mg/m^(3),液压支架行人侧作业点粉尘浓度大于90 mg/m^(3),远远高于国家标准;不同区域内呼尘占比差异较大,破碎机所在区域呼尘占比最高达95%。

“三软”煤层大采高工作面回撤期间综合防灭火技术研究与应用

针对华亭大柳煤矿“三软”煤层大采高工作面回撤期间自然发火隐患进行分析,合理的制定了综合的防灭火技术。对工作面防灭火技术取得的实效进行总结,确保1404工作面回撤期间的安全性。并对制定的综合防灭火技术从安全效益、经济效益、社会效益进行论证。结果表明华亭大柳煤矿“三软”煤层大采高工作面回撤期间综合防灭火技术取得了显著的经济效益,对“三软”煤层大采高工作面煤自燃防治工作具有重要的指导意义。