急倾斜煤层放顶煤分段高度的合理确定

 应用弹塑性理论分析了矿山压力对急倾斜煤层顶煤破碎的作用, 认为在低瓦斯急倾斜煤层中只有当顶煤在支承压力的作用下进入应力极限平衡状态时, 顶煤才可放出, 据此计算顶煤可能的分段高度。但分段高度的确定还需考虑煤层厚度变化的影响, 将煤层厚度视为一个随机变量, 并根据可放度确定合理的分段高度。     

顶煤块度预测方法与应用

以岩(煤)体裂隙网络模拟技术为基础，推导了放顶煤采场项煤三维块度预测法的求解过程与计算公式，提出了顶煤可放性块度评价法及其对应的评价分类指标，用此法来评价顶煤可放性具有直观、可靠性高、易于接受的优点。     

工艺参数对顶煤冒放性影响的数值分析与硬顶煤的预处理

运用相似材料模型试验，得出了顶煤冒放的桥拱式、半拱式和柱式等３种结构。在煤层条件对顶煤冒放性影响的研究的基础上，用有限元正交数值试验，进一步研究了开采工艺参数对顶煤冒放性的影响规律。介绍分析了硬顶煤的预注水软化和预爆破弱化处理方法及应用效果。     

特厚坚硬煤层分层综放开采关键技术研究

通过对特厚坚硬煤层综放开采技术的系统分析，指出提高坚硬顶煤的冒放性和瓦斯的综合治理是该条件下综放开采所面临的主要技术难题。在对特厚坚硬顶煤结构及破碎特点分析的基础上，提出了提高坚硬顶煤冒放性的主要技术途径和措施，在宁夏太西集团白芨沟矿煤层特厚、坚硬、顶板坚硬、高瓦斯和浅埋深条件下，成功地进行了分层综放开采的实践，达到了工作面年产 １５０Ｘ １０４ｔ的生产水平。在该条件下实现了综放开采技术的突破，取得了预期的效果。     

厚硬顶板硬顶煤压缩性分析与综放开采方案选择

顶煤的运移与垮落，尤其是内部微观裂隙的扩展，与其直接项和老项岩层的活动规律密切相关。张双楼煤矿主采煤层为7煤和9煤，两层煤之间赋存唯一一层厚硬岩层，即9煤层的直接项也是7煤层的直接底。9煤较硬，其项煤的可放性和开采方案的选择是其成功应用综放开采技术的关键。采用实验室物理模拟，分析厚硬岩层的破断特征，并根据开采不同布置方式与厚硬岩层的不同断距提出9种上层煤与下层煤不同开采方案，系统分析下层煤项煤压缩量的变化及其可放性。计算机数值模拟与现场实践表明，7煤与9煤的工作面成交错布置方式，先采7煤后采9煤，一次采全高，最有利于9煤工作面的顶煤冒放，保证9煤综放开采的成功。研究结果可为类似条件下的厚硬煤层推广综放开采工艺提供设计指导。     

综放开采顶煤冒放性的损伤力学分析

运用损伤力学的基本原理，阐述了综放开采顶煤在支承压力作用下损伤演化与冒放性之间的关系。利用细观统计损伤力学建立了损伤参量的计算模型，把顶煤损伤参量作为冒放性指标另以研究，并讨论了开采深度、煤层强度、原始裂缝和水平应力对顶煤冒放性的影响，其结论结果和现场实际相吻合。     

综放开采顶煤裂隙及其渗透性研究

在国家自然科学基金重点项目《厚煤层全高开采方法基础研究》资助下,通过对综放开采工作面前方顶煤裂隙的现场观测和实验室顶煤裂隙的细观研究,分析了顶煤裂隙分布的宏、细观特征;运用多重分形理论讨论了顶煤裂隙结构的不均匀性和各向异性;基于现场工作面前方顶煤节理裂隙分布,运用UDEC软件,对同一煤层地质条件下不同厚度的综放开采与分层开采采场进行数值计算;分析了应力变化对裂隙岩体渗流的影响,得出了裂隙岩体的渗透系数与应力的关系表达式,结合综放开采的实际,给出了综放开采工作面前方顶煤渗透系数的数学表达式。主要研究结论为: (1)煤层裂隙的形成不仅受地质因素的影响,而且受采掘等工程因素的影响,因此,在定量研究煤层裂隙渗透性时必须考虑工程因素对裂隙发育程度的影响。裂隙分布表明:顶煤裂隙的分布既有一定的随机性,又有一定的规律性。 (2)简单分形和多重分形研究顶煤裂隙,研究表明:当各方向的D_0值变化越大,则表明顶煤裂隙发育的各向异性就越明显,且某一方向多重分维值C_h越小,则该方向裂隙结构就越复杂,分布也越不均匀;相反,多重分维值C_h值越大,则该方向裂隙体结构就相对均匀。因此,用各向分维值D_0和裂隙不均匀系数C_h可以分别定量表示顶煤裂隙的各向异性和不均匀性。 (3)综放开采的卸压     

煤岩界面弱反射波小波多分辨分析

煤层厚度探测，特别是放顶煤开采时顶煤厚度快速、准确地探测对掌握放煤力度、保证煤质以及准确计算回收率具有重要意义。声波反射法是目前顶煤厚度探测的有效方法之一。弱反射波信号识别是声波法煤层厚度探测中的一个关键问题。针对这一问题，对顶煤厚度探测信号进行了小波多分辨分析；提出了从小波的紧支性、连续性和高阶消失矩3个方面选择小波基对信号进行分解的原则；应用Db4小波对实测信号进行了4层多尺度分解，分析了煤层夹矸和煤层顶板反射波在不同尺度下的时频特征，提高了煤岩界面弱反射波的识别能力和煤层厚度探测的精度。     

云冈矿8621综放面坚硬顶板弱化处理技术

针对同煤集团云冈矿8621综采放顶煤工作面煤层和顶板条件,为了保证在"两硬"条件下综放工作面安全生产,沿12号煤层顶板布置了两条工艺巷,在工艺巷内对坚硬的顶煤和煤层顶板进行爆破预裂弱化,保证了顶煤的顺利下放和高效回收,避免了工作面坚硬顶板大面积悬顶的威胁。     

综放开采顶煤冒放性预测模型的构建与应用

为实现综放开采顶煤冒放性的定量分析,提高资源采出率,采用室内实验、理论分析、数值计算和现场实测等研究手段,测试单轴抗压条件下型煤和原煤中超声波速的全程动态演化特征,构建超声波速预测模型并将其应用于综放开采顶煤冒放性预测。煤体弹性变形阶段,超声波传播速度保持不变,后继屈服阶段,裂隙的萌生和扩展导致超声波速呈现单调降低趋势,残余变形阶段,超声波速降低至残余值并保持稳定;将工作面前方顶煤超声波速分布划分为单阶段(I)、双阶段(I–II)和三阶段(I–III)三种类型,对于I型分布采场,顶煤不具备冒放性,I–II型分布采场,顶煤冒放性差,采出率为50%～70%,I–III型分布采场,顶煤冒放性良好,采出率大于70%;采用累积塑性应变表征煤中裂隙发育程度,构建超声波速预测模型,将预测模型与本构模型耦合实现承载煤体变形破坏过程和超声波速演化特征的准确模拟,采用实验数据验证了模型的可靠性;将超声波速预测模型应用于新柳煤矿顶煤冒放性评价,预测结果表明,该矿综放工作面前方顶煤超声波速分布属于I,II,III三阶段类型,顶煤冒放性良好,实测顶煤采出率为83.3%,煤层垂直应力和顶煤超声波速实测数据与预测结果具有较好的一致性,表明所构建的超声波速预测模型可用于不同开采条件下顶煤冒放性评价。     

浅埋综放L工作面开采方法及其矿压实测研究

 根据路天煤矿16#煤层的具体条件,提出并成功实践L形巷道布置的开采方法。通过现场实测分析,研究L工作面浅埋综放开采时顶煤和顶板的垮落特征、支架的工作阻力、地表塌陷规律及填埋碾压技术等,分析L工作面顶板破裂扩展及分块垮落顺序,建立浅埋综放开采的拱–台阶岩梁组合力学模型,揭示浅埋综放的覆岩移动规律及破煤机制,并给出维护顶板稳定的支架阻力计算公式。研究结果表明：(1) L工作面开采方法是一种高效、安全、高回收率的采煤方法,采露头煤或者露天转井工开采时可以借鉴;(2) 在合适的煤层条件下,浅埋深放顶煤开采在技术上是可行的;(3) 周期来压步距随覆盖层厚度的增加呈增大的趋势;(4) 工作面中部周期来压显现明显;(5) 地表变形垮落可分为4个阶段,填埋碾压应分2个阶段进行;(6) 为提高端面顶板和煤壁的稳定性,应提高支架初撑力。研究结果对类似条件下的开采方法及矿压规律研究具有积极的指导意义。     

3D numerical modeling of longwall mining with top-coal caving

There is a considerable amount of lignite reserve in the form of thick seams in Turkey. It is rather complicated to predict the characteristics of strata response to mining operation in thick seams. However, a comprehensive evaluation of ground behavior is a prerequisite for maintaining efficient production, especially when the top-coal-caving method behind the face is applied. Top-coal caving is the key factor affecting the efficiency of production at thick-coal seams. During production of top coal by caving behind the face not only a significant amount of coal is lost in the goaf but the coal drawn by means of caving is diluted considerably with surrounding rock. Therefore, it is not possible to carry out an efficient production operation unless caving of top coal behind the face is optimized. In this paper, results of 3D modeling of the top-coal-caving mechanism by using the finite difference code FLAC^3D at the M3 longwall panel of the Omerler Underground Mine located at Tuncbilek (Turkey) are presented. According to the modeling results, maximum vertical abutment stresses were formed at a distance of 7 m in front of the face. An analysis of the conditions of top coal has revealed that a 1.5 m thick layer of coal just above the shield supports is well fractured. However, a 3.5 m thick layer of coal above the fractured part is either not fractured or is fractured in the form of large blocks leading to obstruction of windows of shields during coal drawing. It is concluded that, in order to decrease dilution and increase extraction ratio and efficiency of operation, top coal should be as uniformly fractured as possible. Hence, an efficient and continuous coal flowing behind the face can be maintained. A special pre-fracture blasting strategy just sufficient enough to form cracks in the top coal is suggested by means of comparing with the results of numerical modeling.     

综放顶煤放出规律与放煤步距的离散元仿真研究

综放开采的合理放煤步距是研制综放工作面成套技术装备的基础，是提高综放工作面采出率与煤质的关键之一。对颗粒状散体介质离散元软件进行再开发时，单元的接触关系采用弹性及阻尼元件，以适应煤矸放出过程的力学特性，基于Windows环境进行封装处理，通过添加虚拟壁功能实现分层散体介质的仿真处理。在低位综放支架、放煤口水平投影宽度为0.8m条件下，对不同采煤步距(0．6，0．8，1．0，1．2m)的项煤放出规律进行了离散元仿真研究，从顶煤损失与含矸率两个方面分析得到综放合理放煤步距为1．0m，较合理的放煤步距为0．8m，即分别稍大于或等于放煤口水平投影宽度。综放工作面采煤机截深、支架及运输机前移步距应按合理或较合理放煤步距设计。据此研制成功综放成套设备(步距为0．8m)，实现了适应项煤放出规律的一采一放、平行作业的采放工艺，大幅度提高顶煤综放开采的高产高效水平。     

Numerical simulation of the top coal caving process using the discrete element method

How to understand the top coal caving process and increase the top coal recovery ratio is one of the urgent problems to resolve for longwall top coal caving technology. This paper discusses a new theory and technology of top coal caving with vibration. The vibration device is mounted on the shield beam of the top coal caving support. The vibrator destroys the arch structure formed during the top coal caving process, which results in the smooth top coal caving process, and in this way the top coal recovery ratio is increased. The distinct element method (DEM) numerical software particle flow code in 2 dimensions (PFC2D) is used for the numerical simulation. It is proven that the vibration can easily destroy the arch structure which is formed during the top coal caving process. The parameters about when the arch structure would be formed during the top coal caving process have been obtained. The movement of the top coal caving process under the vibration condition makes a more stable layer uniform caving performance. The aim of the top coal caving with vibration technology, to increase the top coal recovery ratio and to lower the waste content rate, has been achieved.     

Stress analysis of longwall top coal caving

Longwall top coal caving (LTCC) is a relatively new method of mining thick coal seams that is currently achieving high productivity and efficiency in application, particularly in China. The technique is similar to traditional longwall mining in that a cutting head slices coal from the lower section of the coal seam onto a conveyor belt installed in front of the hydraulic support near the cutting face. In modern LTCC an additional rear conveyor belt is located behind the support, to which the flow of the caved coal from the upper part of the seam can be controlled by a moveable flipper attached to the canopy of the support. The mining method relies on the fracturing of the top coal by the front abutment pressure to achieve satisfactory caving into the rear conveyor.This paper develops a yield and caveability criterion based on in situ conditions in the top coal in advance of the mining face (yield) and behind the supports (caveability). Yielding and caving effects are combined into one single number called caving number (CN), which is the multiplication result of caving factor (CF) and yield factor (YF). Analytical derivations are based on in situ stress conditions, Mohr–Coulomb and/or Hoek–Brown rock failure criteria and a non-associated elastoplastic strain softening material behaviour. The yield and caveability criteria are in agreement with results from both numerical studies and mine data.The caving number is normalised to mining conditions of a reference Chinese mine (LMX mine) and is used to assess LTCC performance at fourteen other Chinese working longwalls that have had varying success with the LTCC technology. The caving number is found to be in good agreement with observations from working LTCC mines. As a predictive model, results of this analytical/numerical study are useful to assess the potential success of caving in new LTCC operations and in different mining conditions.     

综放开采支承压力与卸压瓦斯运移关系研究

富含瓦斯厚煤层综放开采后，煤岩体中的卸压瓦斯运移规律与其渗透性密切相关，而支承压力变化又对渗透性有很大的影响，即采场卸压瓦斯的运移规律明显受支承压力的影响。分析了采动影响下煤岩卸压瓦斯的流动特性，并根据靖远煤业公司魏家地矿110综放面的矿压观测及瓦斯监测结果，分析得到综放采场前方支承压力及其作用下渗透系数随工作面距离变化的曲线，进而得出综放面支承压力与卸压瓦斯运移的关系，为有效防治综放开采工作面瓦斯事故和合理抽取并利用瓦斯资源提供了理论依据。     

特厚煤层分层放顶煤相似材料模拟试验研究

 借助相似材料模拟试验的研究方法, 讨论了华亭矿区白草峪井田煤5 特厚煤层的放顶煤问题。试验认为: 分3层放顶煤的开采方法是可行的, 分2 层放顶煤的方法是不可行的; 分3 层放顶煤时回收率能够达到要求, 而分2 层时回收率较低。同时也得出放顶煤的最佳分层厚度为12～15 m , 最佳采放比为1∶3 。以上结论为白草峪井田的开采设计提供了重要依据。     

综放采场初压阶段顶板稳定性与顶煤放出率关系探讨

初次来压是综放采场矿压控制的重点之一,而顶煤从垮落到放完是一个动态过程,因此建立与顶煤放出率相关的顶板结构的稳定性判断准则是一个重要的理论课题。本文建立了综放采场顶板结构整体变形失稳和局部铰接失稳的力学模型;根据结构稳定理论和强度理论,得到了保持顶板结构整体变形稳定的顶板容许下沉量和保持岩块局部铰接稳定的顶板容许下沉量,通过与顶板回转下沉运动几何状态所决定的顶板下沉量的对比,分析了顶板结构整体变形稳定和岩块局部铰接稳定相统一的力学条件,从而建立与顶煤放出率相关的综放采场顶板稳定性判断准则;结合具体采场实例,给出了与顶煤放出率相关的综放采场顶板稳定性判断曲线和方法,为现场针对不同顶板设计合理的顶煤放出率,从而实现顶板的安全控制提供理论依据。     

折线型综放面开采顶煤运移破坏规律及支架受力特征的数值模拟研究

应用UDEC2D计算程序,模拟了某矿水平与倾斜联合布置的折线型综采面,揭示了综放开采过程中的采场覆岩与顶煤的运移规律及相应的应力场、破坏场的变化特征,并采用FLAC3D对沿折线型综采面布置的支架的受力及其运移特征进行了分析,研究结果对现场工程实践有一定的指导意义。     

综放孤岛工作面开采技术实践

针对东山煤矿煤层赋存和开采条件,介绍了15号煤层51519综放孤岛工作面回采工艺及防治措施,实现了该工作面安全生产,取得了良好的经济效益,为孤岛工作面综放开采积累了丰富的经验。