Influence of laneway support spacing on methane/air explosion shock wave

A laneway support system provides an available way to solve problems related to ground movements in underground coal mines, but also poses another potential hazard. Once a methane/air explosion occurs in a laneway, inappropriate design parameters of the support system, especially the support spacing, likely have a negative influence on explosion disaster effects. The commercial software package AutoReaGas, a computational fluid dynamics code suitable for gas explosions, was used to carry out the numerical investigation for the methane/air explosion and blast process in a straight laneway with different support spacing. The validity of the numerical method was verified by the methane/air explosion experiment in a steel tube. Laneway supports can promote the development of turbulence and explosion, and also inhibit the propagation of flame and shock wave. For the design parameters in actual laneway projects, the fluid dynamic drag due to the laneway support plays a predominant role in a methane/air explosion. There is an uneven distribution of the peak overpressure on the same cross section in the laneway, and the largest overpressure is near the laneway walls. Different support spacing can cause obvious differences for the distributions of the shock wave overpressure and impulse. Under comparable conditions, the greater destructive effects of explosion shock wave are seen for the laneway support system with larger spacing. The results presented in this work provide a theoretical basis for the optimized design of the support system in coal laneways and the related safety assessments.     

Rockburst hazard determination by using computed tomography technology in deep workface

The rockburst in mines results from the dynamic load coupled with static one in coal seams around workface zones, so it is essential to learn the stress distribution of the coal and surrounding rock for determination of rockburst risk areas. The relationship between the elastic wave velocity and stress applied on coal sample was investigated systematically by laboratory testing, theoretically analysis, as well as on-site observation, and a positive correlation between them under uniaxial compression was put forward. Furthermore, it is drawn that the anomaly of elastic wave velocity reflects the stress changes: the positive anomaly ascertains the stress concentration while the negative anomaly estimates the mining destress and weaken degree, and corresponding assessment criterions and parameters were established respectively. The hazard areas and degree of an island longwall face 16302C were forecasted before coal winning based on the elastic wave anomaly distribution rules using active tremor velocity inversion, monitoring results of mining shocks during exploitation indicate that the consistency between locations of big tremors and where forecasted by computed tomography (CT) exceed 80%. The successful application of this technology achieved remarkable economic and social benefits for disaster control in rockburst mines.     

地震荷载下露天坑边坡模糊随机可靠度分析

为探讨地震荷载下露天坑边坡的稳定性,结合可靠度分析方法及模糊数学理论对边坡工程的可靠度进行分析。以某露天坑边坡工程为例,利用拟静力法分析地震荷载下影响边坡工程可靠度的各个作用力,进而应用可靠度、模糊数学等理论对边坡工程进行可靠度分析,得到该边坡工程的随机失效概率为0.015 9,模糊失效概率为0.100 1。同时,对黏聚力c和内摩擦因数f的均值和方差进行敏感度分析,可知其取值的变化将对失效概率产生线性影响,其中模糊失效概率的敏感度较低,而随机失效概率的敏感度则相对较高。结果表明,模糊随机可靠度分析结果虽偏于保守,但它考虑不确定性因素的影响,更适用于大型工程的施工。     

基于激波理论的新兴煤矿煤与瓦斯突出事故研究

通过分析新兴煤矿煤与瓦斯突出事故,发现在事故中由于煤与瓦斯突出事故诱发了激波的生成,瞬间产生的巨大超压,引起风流逆向,大量瓦斯随逆向风流从突出地点扩散传播至二水平,接触卸载巷电机车架空线所产生的电火花,从而引发瓦斯爆炸事故。提出了突出激波对事故的影响并分析了突出激波的形成及其破坏作用,研究了影响突出激波破坏作用的影响因素,得出参与突出的瓦斯量和瓦斯压力是影响激波强度的关键因素。有助于了解突出后的气流动力演化规律,并为煤与瓦斯突出事故的防灾、救灾措施的制定以及提高矿井的抗灾能力提供了参考。     

运用量纲分析探究爆炸应力波在中远区岩石中的衰减规律

在国内外关于爆炸应力波衰减规律研究成果的基础上,运用量纲分析方法推导得出爆炸应力波在中远区岩石中的一般衰减模型。以青海威斯特德尔尼露天铜矿地质数据为背景,借助LS-DYNA大型动力有限元程序建立双台阶模型进行求解运算,得到监测点应力数据,由数据分布规律确定应力波衰减公式,同时,将求解结果用于拟合推导得出的一般衰减模型,从而得到模拟原型-青海威斯特德尔尼露天矿台阶爆破中远区岩体应力衰减公式。拟合结果表明:运用量纲分析方法推导得出的爆炸应力波一般衰减模型能有效反映应力波在岩石中的衰减规律。     

危险货物集装箱堆场爆炸地震效应对地下结构的安全影响分析

为了研究危险货物集装箱堆场爆炸地震效应对地下结构的安全影响,采用我国《爆破安全规程》以及美国国家公路研究所爆破理论相结合的方法,分析某危险货物集装箱堆场建设项目发生爆炸时对已建隧道的影响。建立三维模型,采用Midas GTS有限元分析软件进行数值模拟分析,经过理论分析与数据拟合,分别确定堆场各点（区域）发生爆炸时隧道壁振动速度与地表爆炸当量的计算模型,确定隧道保护条件,并分别采用隧道壁最大应力模拟计算值进行校验,为堆场选址、堆存货种种类及数量限定提供参考建议。     

岩土介质动静力学参数与介质物理组构参数之间的关系

岩土体是地质历史的产物,有着特定的物质组分和结构构造,从而表现出复杂的工程力学性质。为研究岩土介质动、静力学参数与岩土介质物理组构参数三者的关系,文章结合工程岩土体勘察评价,对岩土介质进行了一系列物理力学测试和波动测试,取得了一定量的测试数据。分析中特别关注了岩土介质的弹性波速与介质密度之间的关系。研究发现,岩样和土样波速与密度测试值在波速-密度参数空间中展现出了几种相对性:整体有序与局部混沌的相对性、分布域位置和结构的确定与域内参数随机分布的相对性、在某一分布域内整体样本无序与各类子样本有序的相对性。把握这几种相对性对于岩土介质的理论研究和工程应用都十分有意义。     

煤田采空区对地面地震动的影响

研究了煤田采空区对地面地震动的影响以及采空巷道的动应力分布。采空巷道用地表下圆孔来近似模拟,入射波场为造成较大震害的SH波。该问题采用镜像法求解,利用波函数展开和内域型Graf加法公式将解答归结为一组无穷代数方程组的求解,截断该无穷代数方程组可求得该问题的数值结果。最后,通过算例考虑了圆孔的动应力集中和地表动位移。结果表明,圆孔的动应力集中和地表的位移取决于入射波频率、角度和圆孔半径、埋深。该研究结果为煤田采空区的地震安全工作提供有益的参考。     

油罐火灾沸溢发生时间预测模型

油罐火灾发生沸溢具有很大的危险性,而沸溢时间的准确预测是目前的一个技术难题。笔者结合宽沸程油品油罐火灾沸溢实验,对油层内部传热过程进行详细分析,认为油罐火灾沸溢事故可近似地看作一无内热源、常物性的非稳态传热问题,其过程包含油水界面不参与换热和参与换热的两个阶段。建立了油罐火灾沸溢发生时间预测模型,对两个不同阶段,分别进行理论分析和数值方法进行求解,并同实验数据对比。结论可信,误差较小,为沸溢机理探讨研究和油罐沸溢火灾的扑救提供了参考依据。计算表明:燃烧速度和油罐底部水层厚度对沸溢时间的影响很大,而降低罐壁温度并不能有效地延迟沸溢的发生。     

炮孔轴向不同间隔方式的爆破地震效应研究

不同装药结构爆破的地震效应存在较大差异,对于间隔装药结构而言,当采用的间隔介质相同时,采用什么样的间隔方式的降震效果更好呢?对此,就底部间隔、中部间隔还是顶部间隔装药方式的地震效应进行了比较研究.综合比较地震振动幅值、频率和振动持续时间等主要因素,3种间隔方式中,孔底间隔装药结构的爆破地震效应最小,其次为孔上部间隔,再次为孔中部间隔.