两柱掩护式综放支架与围岩相互作用相似模拟研究

基于两柱掩护式综放支架新架型,采用大比例相似模拟实验,研究了工作面顶煤的变形破坏特征及支架与围岩相互作用规律,分析了顶梁前后比和支架工作阻力对支架位态和端面顶煤稳定性的影响规律.结果表明:随顶煤硬度减小,控顶区顶煤和两柱掩护式综放支架位态稳定性同时下降;顶煤较软时,放煤区和端面区顶煤的失稳并不断扩大直至贯通是导致支架-围岩系统失稳的原因,提出了顶煤双区失稳的概念;在软煤条件下,支护的关键是通过控制放煤量限制放煤区顶煤的垮落线前移,提高支架支护质量,控制端面冒顶,实验工作阻力设定值由2.7 MN增加到5.5 MN,端面冒顶高度由2.13m减小到1.66m,顶梁前后比设定值由2.38减小到1.49时,端面冒顶高度由1.75m减小到0.915 m,同时顶梁回转角度变化由16.8°减小到1.2°.     

大倾角综放面端面顶煤稳定性控制数值模拟及应用

大倾角松软煤层综放面实现高产高效的关键之一是端面顶煤稳定性控制.利用FLAC3D数值模拟软件,分析了放项煤采场覆岩与顶煤的应力场特征、端面顶煤的破坏规律以及位移特征.结果表明:端面顶煤产生较大变形,处于应力降低区;煤壁前方项煤在支承压力作用下产生破坏区,遍布整个煤层;上端头的围岩片帮控制是应重点加强的关键部位;工作面上部支架后底座下滑是支架失稳最先出现和最常见的现象.通过及时支护、提高支护质量等围岩稳定性控制措施,可以取得良好的端面顶煤稳定性控制效果.     

两柱支掩式支架适应性研究

本文以柴里、阳泉及徐州等矿的实测资料为基础,并通过相似模型的实验室研究,着重分析了影响端面顶板冒落的主要因素,即端面距与支架顶梁工作状态。同时分析了这种架型支架的承载能力与顶板破碎状态的关系,以及这种支架平衡千斤顶耳座损坏的原因及改善办法。     

长壁工作面矿山压力的模拟研究

本文以不同条件下两个工作面矿压显现观测资料为基础,进行了相似材料模型试验和有限单元法模拟电算。研究了上覆岩层的变形、移动和应力分布的规律,分析了支架工作阻力与顶板岩层的应力分布以及顶板下沉量之间的关系。研究结果表明,一个工作面的支架设计工作阻力是合理的,而另一个则偏大。     

巨厚砾岩层下综放采场矿压显现规律

巨厚砾岩层下综放采场矿压显现规律研究对于采场围岩控制和安全生产具有重要的现实意义.采用理论分析和义马矿区千秋煤矿矿压观测方法进行研究,得出结论为:综放工作面围岩可控程度属于难控围岩,即采场顶底板围岩控制困难.选出了ZF7000-18/28型放顶煤基本支架及其综放面合理配套设备;现场观测研究了综放面矿压显现规律,得出了采场顶板来压步距、来压强度等参数.采场矿压显现明显,不同区域来压具有不一致性.顶板周期来压时支架循环末工作阻力最大值为4 307.70 kN,为支架额定工作阻力的61.54%.因此,采场支架可靠性能较高,现场应用试验效果显著,矿井实现了"一井一面"生产模式,推动了安全高效矿井建设.     

坚硬厚层顶板的破断失稳及其控制研究

以晋华宫煤矿坚硬厚层顶板条件为工程背景,通过理论分析与现场实测相结合,研究了厚层坚硬顶板的临界失稳条件、失稳方式、影响失稳的因素以及失稳的机理,提出了厚层坚硬顶板失稳控制的方法.研究表明,岩层自身属性及赋存特点对坚硬厚层顶板破断后的承载具有重要影响;坚硬厚层顶板断裂失稳的发展受顶板断裂长度的影响显著,而提高支架支护强度对顶板断裂失稳的控制作用是有限的;提出对厚层顶板实施爆破预裂减小顶板断裂长度和合理支架选型提高支架支护强度相结合的顶板控制方法.通过在晋华宫煤矿8210工作面的应用实施,工作面支架末阻力与时间加权阻力分别占额定工作阻力的85.3%与83.7%,工作面顶板随采随垮,煤壁片帮深度控制在0.2～0.3m范围.     

厚煤层大采高采场煤壁的破坏规律与失稳机理

基于大采高采场煤壁稳定性控制需要,在现场实测基础上,采用数值模拟分析了煤层采动裂隙的发展演化规律,并用滑移线理论分析了煤壁失稳的力学过程.研究表明:仅含层理煤层的采动剪切破坏面由倾向相反的共轭面组成;含节理煤层中,硬煤的采动破坏面为剪切破坏面与节理张裂面组成的倾向相反的共轭面,软煤采动破坏面为倾向采空区的单向平面;超前塑性区内硬煤的后继剪切破坏面仍为倾向相反的共轭面,软煤内则为倾向煤壁的单向平面.采用塑性滑移线确定了煤壁片帮的危险范围,影响煤壁失稳的主要因素为端面距与砌体梁结构的回转变形压力.     

耿村煤矿综放开采覆岩移动和矿压显现规律研究

厚煤层综放开采矿山压力和围岩控制一直是综放开采研究的重点问题。基于义马矿区耿村煤矿特厚煤层综放工作面的地质采矿条件,采用数值模拟和现场矿压观测的方法,对综放工作面覆岩移动和矿压显现规律进行研究。结果表明:(1)综放工作面上方老顶形成"三铰拱"形砌体结构,该结构初次失稳和周期性失稳造成工作面初次来压和周期来压。老顶来压后,工作面前方支承压力趋于稳定,主要表现在最大应力集中系数和塑性区范围基本保持不变。(2)综放工作面顶板周期来压步距14.4~17.5 m,平均16.2 m,顶板来压动载系数1.81~2.04,平均1.92,顶板来压明显但较缓和。顶板来压期间支架时间加权平均工作阻力为其额定工作阻力的72.2%,选用ZF8600/18/35D型放顶煤液压支架合理。研究结果可为义马矿区综放开采围岩控制提供技术支撑。     

液压支架初撑力及围岩蠕变对支架阻力特性的影响

本文在运用简单易行的工程实测方法的基础上,研究了长壁工作面液压支架的负载特征,指出支架初撑力的大小对工作面直接顶的稳定性和支架本身的阻力特性有着显著的影响。在中稳以下顶板条件下,掩护支架的初撑力与额定工作阻力的比值应在60％以上,才能有效地管理顶板并取得较好的技术经济效果。工作面实测资料亦表明,在一个采煤循环中,因围岩蠕变引起的支架阻力增量约为100t/架左右,因而在考虑支架阻力参数时,围岩蠕变是一个不可忽视的因素。     

极软厚煤层大采高台阶式综采端面煤岩稳定性控制研究

基于对极软突出厚煤层大采高综采工作面端面煤岩稳定性的有效控制,提出了台阶式采煤工艺,采用台阶式割煤方式;用数值模拟分析了台阶式割煤的防片帮机理.现场实测分析了大采高开采工作面在采用台阶式回采工艺条件下端面煤岩的失稳特征.研究表明:台阶式割煤工艺改善了煤壁区域的应力状态,减少了工作面煤壁片帮和端面冒顶的发生不同台阶高度比割煤所引起的围岩破坏程度不同,上下台阶高度比为1:2时煤壁塑性破坏区最小;极软厚煤层大采高开采煤壁片帮主要以剪切滑移引起的三角斜面片帮为主,超高开采是端面顶板冒落的主因.     

Analysis of stability of support and surrounding rock in mining top coal of inclined coal seam

The study analyzes the characteristics of roof movement in mining top coal of inclined coal seam, and establishes the mechanical model of support and surrounding-rock stability in inclined coal seam. Besides, this study carries out the numerical calculation and field observation of roof movement and support stability, and provides the critical control measures. The results show that the fracture firstly appears in middle-upper roof and extends upwards in top coal caving in inclined coal seam; regular and irregular caving zones appear in middle-upper stress concentration region, and the asymmetric caving arch is finally formed. Support load of middle-upper working face is larger than that of the middle-lower face; dynamic load coefficient of upper support is large, and the load on the front of support is larger than that on the rear of it, which leads to poor support stability. Stability of support and surrounding-rock system depends mainly on upper-support stability.     

两硬综放面矿压显现规律研究

根据忻州窑矿８９１６综放面的矿压观测，系统地分析了两硬条件下综放开采的矿压显现规律。文章的结论是：两硬条件下的综放面既具有坚硬顶板带冲击载荷的悬梁式破断规律，又具有综放开采的动载系数小，支架载荷低的显现特征，采场控制仍要有高强度的支撑和必要的顶板预处理措施。     

Rock mechanical investigation of strata loading characteristics to assess caving and requirement of support resistance in a mechanized powered support longwall face

Longwall mining is one of the most acclaimed and widely used in underground method for coal extraction. The interaction of powered supports with the roof is the key issue in strata mechanics of longwall mining. Controlled caving of rock mass is a prerequisite pro thriving exploitation of coal deposits by longwall retreat with caving technique and support resistance has evolved as the most promising and effective scientific tool to predict various aspects related to strata mechanics of such workings. Load density,height of caving block, distance of fractured zone ahead of the face, overhang of goaf and mechanical strength of the debris above and below the support base have been found to influence the magnitude of load on supports. Designing powered support has been attempted at the different countries in different methods. This paper reviews the mechanism of roof caving and the conventional approaches of caving behaviour and support resistance requirement in the context of major strata control experiences gained worldwide. The theoretical explanation of the mechanism of roof caving is still continuing with consistently improved understanding through growing field experiences in the larger domain of geo-mining conditions and state-of-art strata mechanics analysis and monitoring techniques.     

两硬综放面顶煤顶板冒放结构探讨

用深基点观测和理论分析的方法揭示坚硬顶板、坚硬煤层条件下综放开采顶煤顶板活动规律及其冒放结构，结论对生产有现实的指导意义。     

Top coal flows in an excavation disturbed zone of high section top coal caving of an extremely steep and thick seam

Compared with gentle dip long-wall caving, the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short, while its horizontal section is high with increasing production. But the caving ratio is low, which might result in some disasters, such as roof falls, induced by local and large area collapse of the top coal in a working face and dangers induced by gas accumulation. After the development of cracks and weakening of the coal body, the tall, broken section of the top coal (a granular medium) of an extremely steep seam (over 60°) shows clear characteristics of nonlinear movement, We have thoroughly analyzed the geological environment and mining conditions of an excavation disturbed zone. Based on the results from a physical experiment of large-scale 3D modeling and coupling simulation of top coal-water-gas, we conclude that the weakened top coal can be regarded as a non-continuous medium. We used a particle flow code program to compare and analyze migration processes and the movements of a 30 m high section top coal over time before and after weakening of an extremely steep seam in the Weihuliang coal mine. The results of our simulation,experiment and monitoring show that pre-injection of water and pre-splitting blasting improve caving ability and symmetrical caving, relieve space for large area dynamic collapse of top coal, prolong migration time of noxious gases and release them from the mined out area and so achieve safety in mining.     

Coupling effects of coal pillars of thick coal seams in large-space stopes and hard stratum on mine pressure

Concerning the issue of mine pressure behaviors occurred in fully mechanized caving mining of thick coal seams beneath hard stratum in Datong Mining Area, combined with thin and thick plate theory, the paper utilizes theoretical analysis, similar experiments, numerical simulations and field tests to study the influence of remaining coal pillars in Jurassic system goaf on hard stratum fractures, as well as mine pressure behaviors under their coupling effects. The paper concludes the solution formula of initial fault displacement in hard stratum caused by remaining coal pillars. Experiments prove that coupling effects can enhance mine pressure behaviors on working faces. When inter-layer inferior key strata fractures, mine pressure phenomenon such as significant roof weighting steps and increasing resistance in support.When inter-layer superior key strata fractures, the scope of overlying strata extends to Jurassic system goaf, dual-system stopes cut through, and remaining coal pillars lose stability. As a result, the bottom inferior key strata also lose stability. It causes huge impacts on working face, and the second mine pressure behaviors. These phenomena provide evidence for research on other similar mine strata pressure behaviors occurred in dual-system mines with remaining coal pillars.     

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.     

复杂条件下大倾角对放顶煤冒放规律的影响研究

根据申家庄煤矿2208工作面具体的工程地质条件,理论分析了大倾角对顶煤冒放性的影响,指出大倾角将使工作面上、中、下部产生三种性质不同的力学结构,并通过RFPA有限元软件分别对这三种结构的冒放特征进行了数值模拟,揭示了大倾角煤层顶煤的冒放规律,对该矿优化采煤工艺、提高煤炭采出率有重要指导意义。     

复杂条件下大倾角对放顶煤冒放规律的影响研究

根据申家庄煤矿2208工作面具体的工程地质条件，理论分析了大倾角对顶煤冒放性的影响，指出大倾角将使工作面上、中、下部产生三种性质不同的力学结构，并通过RFPA有限元软件分别对这三种结构的冒放特征进行了数值模拟，揭示了大倾角煤层顶煤的冒放规律，对该矿优化采煤工艺、提高煤炭采出率有重要指导意义。