QY200型液压支架立柱优化设计分析

在采煤过程中,液压支架作为煤矿开采的支护设备,其强度性能决定煤矿开采的安全指数。前期研究表明液压支架的应力主要集中在柱窝处,其应力大小和立柱的结构有关,在此前提下,针对QY200型液压支架的立柱结构进行优化。在不改变柱窝直径大小的前提下,对立柱的结构尺寸进行优化设计,优化试验采用正交试验设计法,将液压支架整体应力接近最小作为优化目标。优化结果表明,液压支架最大等效应力随活柱长度的增加成增长趋势,为保证液压支架能够更稳定地工作,活柱长度越小越好,而大缸外径和大缸长度越大越好。该优化方法能够减小试验次数,提高设计效率。     

固体充填开采直接顶位态控制机制及工程案例

基于充填开采岩层移动特征与实际采场中的8种典型覆岩载荷形式,建立了四柱充填采煤液压支架顶梁的平衡方程,分析了不同覆岩载荷形式下立柱的受力状态,结合工程实测确定支架顶梁最优载荷形式为二次曲线;构建了充填采煤液压支架与充填体协同控顶的力学方程;分析了直接顶位态的主要影响因素,揭示了固体充填开采直接顶位态控制机制,即充填体弹...     

磁弹性应力传感器检测支架载荷试验研究

液压支架是煤矿开采中的支护设备,其载荷的检测问题一直是没有得到很好解决．根据液压支架的受载特点,提出了应用磁弹性原理检测其外载荷的方法;根据支架的结构特点,研制了适合测量支架上不同受力构件的十字桥式磁弹性应力传感器,并以此对单体液压支柱和模拟连杆试件进行了加载检测试验．结果表明,液压支柱及连杆在不同载荷下,传感器的输出信号与载荷之间具有近似线性关系的规律性．进而讨论了用磁弹性应力传感器检测支架载荷的可行性．     

苏联应用掩护支架采煤法的成就和经验

Ⅰ引言 齐纳卡尔教授的掩护支架采煤法。是在１９３５年创立的,经过近５年的试验和改进,１９４０年起它就在苏联库兹　茨煤矿区获得了日益广泛的应用。目前在库兹　茨南部煤矿区,用掩护支架采煤法所采的煤达该区产量的５０％左右。 １９５４年出版的“掩护支架采煤法的改善”《　　　　》 比较全面地说明了苏联在掩护支架采煤法的应用和改进方面的新成就（内容是根据１９５２年１１月在库兹　茨举行的“掩护支架采煤法改进途经”会议的材料）。它使我们对掩护支架采煤有了新的认识和了解。 掩护支架采煤法的优点被进一步肯定了,而它的主…     

弹性底板上的液压支架整体尺寸参数优化

基于弹性地基梁理论,建立了弹性底板上的液压支架底座受力分析模型,以前后连杆力最小、结构尺寸最小、掩护梁弯矩最小、支护效率最高、弹性底板比压最小为5个优化目标函数,通过序列二次规化法对液压支架的整体尺寸设计参数进行优化,实现了不同底板状况下的整体尺寸参数优化,基于MATLAB/GUI可视化编程,实现了程序的可视化.算例分析表明,将底板比压作为优化目标函数对液压支架整体进行优化,在结构尺寸变化不大的前提下,优化结果不仅能满足设计要求,而且力学特性有较大的改善,前后连杆轴力、底板比压、掩护梁弯矩4个参数较优化前平均减少了31.95%.     

对煤矿用液压支架电控系统的研究

为了提升煤矿采煤效率需要对矿用液压支架系统进行研究,目前大部分的煤矿采用的液压支架都为手动操控方式,该种操控方式比较传统,在实际的采煤环节中工作效率不高,并且其运行可靠性比较低.基于电控的煤矿液压支架电控系统的实际应用能够有效的提升煤矿作业效率,动作准确性比较高,基于此,在本文中将对煤矿用支架的电控系统进行深入的研究.     

青岛市太阳能光伏电站及其支架设计

针对青岛市光伏电站设计中的有关问题,本文基于青岛市特殊的海洋气候,对青岛并网式太阳能光伏电站的基本结构进行设计,同时,在满足太阳能电池板获得最大日太阳光辐射量的条件下,设计太阳能电池板支架,并参照青岛市最大风力值44.2m/s求出风载,以此为有限元分析依据,建立光伏支架总装受力分析的有限元模型,并进行静力学分析,同时对支架进行结构优化。研究结果表明,优化后,光伏支架最大变形为0.118 6mm,最大应力为19.725 MPa,说明优化后光伏支架的变形和应力均大幅降低,满足304不锈钢强度的要求。该研究为建设太阳能光伏电站提供了非常重要的参考价值。     

约束边界和销轴简化对液压支架强度影响

为准确分析液压支架在顶梁扭转加载试验时的强度特性,以ZY6800/08/18D型液压支架为研究对象,采用整机建模的方式,建立了液压支架的三维实体有限元模型.根据液压支架试验的测试结果,选取仿真模型上的测点位置,分析对比顶梁和底座在8种不同的约束边界条件下,液压支架的应力分布情况,同时分析带摩擦的接触边界条件下底座和平台的接触应力分布及接触状态,指出顶梁扭转加载时的载荷不对称导致的底座不完全接触的现象.在不改变顶梁和底座约束边界的条件下,分析4种销轴连接简化方法对液压支架整体应力分布的影响.对比仿真结果与测试结果,分别评估各种边界条件和不同销轴连接简化方法的准确性,以及对仿真效率的影响.结果表明,液压支架的顶梁边界选择固定支撑,底座边界选择与工作台摩擦接触,保留销轴并将销轴与轴孔绑定接触得到的仿真结果最接近试验结果,且有较高的计算效率.研究结果可为液压支架设计过程中准确预估应力分布提供依据和参考.     

有限元法在液压支架设计中的应用

将带四连杆机构的掩护式液压支架简化成一个计算模型，从静力学和运动学两个方面，分析了该模型的受力情况，并在此基础上采用三维有限单元法，研究了ＢＹ５４０－１０．７／２７．５型支架的应力分布状况及使支架轻型化的主要途径，进而为液压支架设计提供了理论依据。     

ZY6400/21/45型液压支架底座强度分析和结构优化

底座是液压支架非常重要的承载原件.依据液压支架国家标准GB 25974. 1—2010《煤矿用液压支架第1部分:通用技术条件》,选取两种危险工况对支架进行有限元分析,根据静应力分析结果观察整机应力分布状况和位移变化趋势,从中发现液压支架存在的初始设计问题,最后着重对底座的强度进行优化,使支架的整体强度得到了提高.     

Hydraulic support crushed mechanism for the shallow seam mining face under the roadway pillars of room mining goaf

While the fully-mechanized longwall mining technology was employed in a shallow seam under a room mining goaf and overlained by thin bedrock and thick loose sands, the roadway pillars in the abandoned room mining goaf were in a stress-concentrated state, which may cause abnormal roof weighting, violent ground pressure behaviours, even roof fall and hydraulic support crushed(HSC) accidents. In this case,longwall mining safety and efficiency were seriously challenged. Based on the HSC accidents occurred during the longwall mining of 3-1-2 seam, which locates under the intersection zone of roadway pillars in the room mining goaf of 3-1-1 seam, this paper employed ground rock mechanics to analyse the overlying strata structure movement rules and presented the main influence factors and determination methods for the hydraulic support working resistance. The FLAC3 D software was used to simulate the overlying strata stress and plastic zone distribution characteristics. Field observation was implemented to contrastively analyse the hydraulic support working resistance distribution rules under the roadway pillars in strike direction, normal room mining goaf, roadway pillars in dip direction and intersection zone of roadway pillars. The results indicate that the key strata break along with rotations and reactions of the coal pillars deliver a larger concentrated load to the hydraulic support under intersection zone of roadway pillars than other conditions. The ‘‘overburden strata-key strata-roadway pillars-immediate roof" integrated load has exceeded the yield load that leads to HSC accidents. Findings in HSC mechanism provide a reasonable basis for shallow seam mining, and have important significance for the implementation of safe and efficient mining.     

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.     

深部沿空切顶成巷围岩稳定性控制对策

基于沿空切顶成巷技术原理,以城郊煤矿深部工作面无煤柱开采为背景,综合运用力学分析﹑模拟计算和现场试验等方法,对深部切顶成巷围岩控制关键对策进行深入研究。结果显示：切顶留巷顶板在侧向形成短臂梁结构,降低了巷旁支护体所受压力,切缝范围内岩层垮落后碎胀充填采空区,使留巷顶板下沉量降低了约50%。采空区侧顶板为切顶巷道围岩变形的关键部位,需进行加强支护;深部切顶巷道实体煤帮塑性区范围大,通过煤帮锚索支护技术可将浅部锚杆承载层锚固在弹性区稳定煤体中;深部切顶成巷来压速度快、强度大,巷内单体支柱易造成冲击破断,采用高阻力液压支架巷内临时支护时可较好地抵抗深部强动压;巷旁刚性挡矸装置因无法适应深部围岩大变形而受压弯曲破坏,深部切顶巷道巷旁挡矸结构需实现一定的竖向让位卸压方可与顶底板协调变形。在研究的基础上提出恒阻锚索关键部位支护+可缩性U型钢柔性让位挡矸+巷内液压支架临时支护+实体煤帮锚索补强的深部切顶成巷联合支护技术,并进行现场工业性试验。现场监测结果表明：留巷围岩在滞后工作面约290 m时基本稳定,且稳定后各项指标满足下一工作面使用要求。     

One-piece coal mine mobile refuge chamber with safety structure and less sealing risk based on FEA

In order to reduce the risk of sealing and improve the structural strength for a coal mine mobile refuge chamber,a new type of one-piece model was designed.Mechanical and mathematical calculation performed an important role.Calculated according to statics and relevant contents,the structure had the same total volume as the traditional segmented structure,but had shorter length,wider width and greater height.Those prevented the structure from stress or deformation failure.Some reinforcing ribs with enough moments of inertia were welded in the external shell.Because of the one-piece structure,this refuge chamber reduced the risk of sealing which was a serious problem of segmented structure.Impact load with 300 ms duration and0.6 MPa over-pressure was settled.Explicit nonlinear dynamic analysis program was used to simulate the response of the refuge chamber.The maximum stress and the maximum displacement were obtained.The refuge chamber including blast airtight doors could meet the rigidity requirement.Weak parts of the chamber were the front and back end shell where bigger displacement values occurred than others.Thus,the calculation indicated that the refuge chamber could meet structural safety requirements.Based on the numerical analysis,suggestions were put forward for further resistance ability improvement.Only large inclined shaft with larger wellhead was suitable for this one-piece coal mine mobile refuge chamber.     

Technical parameters of drawing and coal-gangue field movements of a fully mechanized large mining height top coal caving working face

Under fully mechanized, large mining height top coal caving conditions, the shield beam slope angle of the support increases due to the enlargement of the top coal breaking and caving space. This results in a change of the caving window location and dimensions and, therefore, the granular coal-gangue movement and flows provide new characteristics during top coal caving. The main inferences we draw are as follows. Firstly, after shifting the supports, the caved top coal layer line and the coal gangue boundary line become steeper and are clearly larger than those under common mining heights. Secondly, during the top coal caving procedure, the speed of the coal-gangue flow increases and at the same drawing interval, the distance between the coal-gangue boundary line and the top beam end is reduced. Thirdly, affected by the drawing ratio, the slope angle of the shield beam and the dimensions of the caving window, it is easy to mix the gangue. A rational drawing interval will cause the coal-gangue boundary line to be slightly behind the down tail boom lower boundary. This rational drawing interval under conditions of large mining heights has been analyzed and determined.     

轮边驱动电动客车扭杆弹簧双横臂独立悬架强度分析方法

针对轮边驱动电动客车的扭杆弹簧双横臂独立悬架强度分析方法不成熟的问题,在分析该类悬架结构特点的基础上,利用有限元技术,构建适用于该悬架特征的有限元分析模型;将经过有效性验证的模型用于评估悬架强度,形成轮边驱动电动客车扭杆弹簧双横臂独立悬架的强度分析方法。以轮边驱动电动客车扭杆弹簧双横臂独立悬架为案例,计算7种典型载荷工况下的悬架等效应力及位移,结果表明:衬套、球铰、限位块等刚度和自由度的合理设置以及预载的正确施加验证了该模型的有效性;由于扭杆支架结构的薄弱性、结构承载的不均衡性以及存在扭杆弹簧应力集中的情况,导致极限工况下最大等效应力达到1 800 MPa,强度不满足设计要求。最后根据计算结果提出结构优化建议,并进一步通过计算验证了结构改进的有效性,整个悬架在极限工况下的最大等效应力降低为993 MPa,扭杆支架最大等效应力在700 MPa以内。     

Characteristics of stress distribution in floor strata and control of roadway stability under coal pillars

Given the difficulties encountered in roadway support under coal pillars, we studied the characteristics of stress distribution and their effect on roadway stability, using theoretical analysis and numerical simulation. The results show that, under a coal pillar, vertical stress in a floor stratum increases while horizontal stress decreases. We conclude that the increased difference between vertical and horizontal stress is an important reason for deformation of the surrounding rock and failures of roadways under coal pillars. Based on this, we propose control technologies of the surrounding rock of a roadway under a coal pillar, such as high strength and high pre-stressed bolt support, cable reinforcement support,single hydraulic prop with beam support and reinforcement by grouting of the surrounding rock, which have been successfully applied in a stability control project of a roadway under a coal pillar.     

Mechanisms of support failure and prevention measures under double-layer room mining gobs – A case study: Shigetai coal mine

In the practice of mining shallow buried ultra-close seams, support failure tends to occur during the process of longwall undermining beneath two layers of room mining goaf (TLRMG). In this paper, the factors causing support failure are summarized into geology and mining technology. Combining column lithology and composite beam theory, the key stratum of the rock strata is determined. A finite element numerical simulation is used to analyze the overlying load distribution rule of the main roof for different plane positions of the upper and lower room mining pillars. The tributary area theory (TAT) is adopted to analyze the vertical load distribution of each pillar, and dynamic models of coal pillar instability and main roof fracture are established. Through key block instability analysis, two critical moments are established, of which critical moment A has the greater dynamic load strength. Great economic losses and safety hazards are created by the dynamic load of the fracturing of the main roof. To reduce these negative effects, a method of pulling out supports is developed and two alternative measures for support failure prevention are proposed: reinforcing stope supports in conjunction with reducing mining height, or drilling ground holes to pre-split the main roof. Based on a comprehensive consideration of economic factors and the two categories of support failure causes, the method of reinforcing stope supports while reducing mining height was selected for use on the mining site.     

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.