不同采厚下的导水裂隙带发育高度研究

为延长矿井服务年限,实现煤矿安全生产,同时应用好综合防治水技术,主要分析不同采厚高度（3 m、6 m、9 m）下综放开采工作面的垂直位移变化情况。分析表明：上覆岩层的垂直位移随着煤层开采厚度的增大而增大,且下沉盆地也随着煤层的开采而显著增大;当采厚较小时,导水裂隙带发育高度随着采高的增大而显著增大,当出现裂隙带发育至松散层时,继续增大采高,裂隙带反而缓慢发育。     

基于钻孔电视成像的导水裂隙带高度确定

三山岛金矿新立矿区东北翼矿体被海水和第四系覆盖,目前该区域回采至-135 m中段,为安全回采,预留厚近120 m护顶层矿柱,压占了大量的矿产资源.在确保安全回采的前提下,为了尽可能回收上部矿体资源,采用GD3Q-GA全景数字钻孔电视摄像系统,在55勘探线-135 m中段及-240 m中段上盘巷道内施工钻孔,对开采上部矿...     

A New Ductile Fracture Criterion for Various Deformation Conditions Based on Microvoid Model

To accurately predict the occurrence of ductile fracture in metal forming processes, the Gurson-Tvergaard (GT) porous material model with optimized adjustment parameters is adopted to analyze the macroscopic stress-strain response, and a practical void nucleation law is proposed with a few material constants for engineering applications. Mechanical and metallographie analyses of uniaxial tension, torsion and upsetting experiments are performed. According to the character of the metal forming processes, the basic mechanisms of ductile fracture are divided into two modes: tension-type mode and shear-type mode. A unified fracture criterion is proposed for wide applicable range, and the comparison of experimental results with numerical analysis results confirms the validity of the newly proposed ductile fracture criterion based on the GT porous material model.     

A New Ductile Fracture Criteria Applied to Various Deformation Conditions Based on Micro-void Model

To accurately predict the occurrence of ductile fracture in metal forming processes, the Gurson-Tvergaard (GT) porous material model with optimized adjustment parameters is adopted to analyze the macroscopic stress-strain response, and a practical void nucleation law is proposed with a few material constants for engineering applications. The mechanical and metallographic analyses of uniaxial tension, torsion and upsetting experiments are performed using specimens with different geometries. According to the character of the metal forming processes, the basic mechanisms of ductile fracture are divided into two modes: tension-type mode and shear-type mode. The corresponding fracture criteria are put forth for wide applicable range, and the comparison of experimental results with numerical analysis results confirms the validity of the newly proposed ductile fracture criteria based on the GT porous material model.     

基于裂纹扩展模型的脆性岩石破裂特征及力学性能研究

为了探究初始微裂纹参数分布对岩石破裂特征及力学性能的影响,进一步系统地了解脆性岩石破裂演化过程,依据线弹性断裂力学理论,建立了非均质性二维细观弹性损伤模型,并运用FLAC^2D数值分析软件,数值模拟研究了单轴压缩条件下不同形态岩石试样的破裂过程。研究结果表明,当初始微裂纹长度和角度服从不同的随机分布时,岩石材料表现出不同的破裂特征,其中初始微裂纹长度和角度均服从正态分布时,岩石破裂区域较完整;初始微裂纹长度或角度服从均匀分布和指数分布时,岩石破裂区域较分散;初始微裂纹角度对于解释脆性岩石单轴抗压试验时岩石试样出现剪切破坏和劈裂破坏的原因具有一定的指导意义,且当初始微裂纹角度均值ɑ=45°时,模型具有最小的峰值强度和轴向最大应变。模型还模拟了脆性岩石单轴抗压试验、巴西劈裂试验和断裂韧度试验的演化过程,模拟结果与试验结果具有较高的一致性。     

高炉软熔带气体流动的数值模拟

建立了气体流动的二维轴对称数学模型,对倒Ｖ形软熔带附近的气体流动进行了数值模拟,用阻力比的概念分析探讨了软熔带附近的气体流动,形象地再现了软熔带对气流的二次分布。     

自然崩落法覆盖岩层下放矿贫化实验研究

自然崩落法放矿基本上都是在覆盖岩层下进行的。在放矿过程中，覆盖岩层废石会混杂在崩落矿石中从放矿漏斗一起放出，造成放出矿石贫化。经研究表明，覆盖岩层下放出矿石贫化的原因主要有两个：一是放矿高度到达矿岩接触面而引起的接触面上贫化；另外就是覆盖层中细小废石颗粒的渗透作用引起的矿岩提前贫化。从实验的角度出发，结合崩落矿岩散体性质及流动特点，分别采用不同矿石颗粒组成和废石颗粒组成，对覆盖岩层下放矿进行室内实验，探明崩落矿岩块度非均匀性对放矿贫化的影响，对放矿控制具有实践指导意义。     

破碎区段管缝式锚杆支护应用研究

管缝式锚杆作为一种支护方式,因具有岩体类型适应性强、及时施加主动预应力以及安装效率高等诸多优点而广泛应用于我国采矿地下工程支护的实践中。结合焦家金矿寺庄矿区生产实际,从RMR岩体质量分级和弹性力学观点出发,分析了管缝式锚杆径向和轴向应力状态。介绍了寺庄矿区推广使用管缝式锚杆进行围岩主动支护情况,实践表明,管缝式锚杆对于岩金矿床岩体具有良好的锚固支护效果,可为同类型相似矿山提供借鉴。     

混凝土结构软岩大巷断裂过程非线性数值模拟

引入断裂力学原理,以某混凝土结构副大巷中复杂结构为研究对象,通过相似模拟实验和现场观测等手段对有关材料物理力学参数进行识别和修正,结合现场矿压观测结果和相似材料模拟试验结果,对该巷道内部应力破坏敏感部位的内力和变形机理进行了系统的分析、模拟计算.研究结果对现场支护设计、维护加固和提高岩层稳定程度具有重要的意义.     

垃圾焚烧炉后拱高度的数值模拟

后拱高度是影响垃圾焚烧炉内燃烧和流动的关键因素之一。采用Fluent作为工具,通过模拟计算得到后拱高度变化对炉膛内流场的影响。计算结果显示,随后拱高度增加,前拱下方处的涡流强度先增加,涡流强度越大越有利于前拱处入炉垃圾的干燥和热解,但当后拱高度达到一定值后,随后拱高度增加,前拱下方处涡流强度开始减弱,直至涡流完全消失,对垃圾的焚烧产生不利影响。在垃圾焚烧炉设计中,选择适当后拱高度非常重要,它直接影响垃圾的燃烧效率。     

双层气雾化喷嘴结构突出高度的数值分析

采用计算流体软件Fluent,通过对双层气雾化喷嘴气流场、颗粒粒径以及温度场的数值模拟,分析导液管突出高度对气流场、颗粒粒径以及温度场的影响。结果表明,导液管突出高度为6mm时气流场结构最优,雾化所得粒径最小。总结气雾化过程中液滴在特殊气流场中破碎的主要过程,为双层气雾化喷嘴结构设计及机理研究提供一定的借鉴意义。     

Laboratory Measurements of Void Fraction and Turbulence in the Bore Region of Surf Zone Waves

Laboratory measurements of the instantaneous free surface, horizontal velocity, and void fraction fluctuations were made simultaneously for three cases of regular waves breaking on a plane slope. The data were reduced by ensemble averaging to quantify the temporal variation of the turbulence intensity and void fraction above trough level in the aeration region of the breaking waves. The cross-shore location of the measurements was restricted to the transition region marked by a rapid decrease in wave height. The study showed that the maximum ensemble-averaged void fractions were between 15 and 20% and that the temporal variation of the normalized void fraction above the still water level could be modeled by linear growth followed by exponential decay. The temporal variation of void fraction above the still water normalized by the wave period and average void fraction appears to be self-similar.