地铁浅埋岛式站台列车火灾烟气蔓延的数值模拟研究

地铁车站及地铁列车为人流密集的公众聚集场所,一旦发生火灾事故,伤亡损失往往非常惨重。地铁作为现代化的城市轨道交通工具,承担着越来越重要的大客流运输任务。因此,深入开展地铁火灾安全的研究有助于地铁安全管理工作。针对地铁浅埋岛式站台列车火灾情况,利用数值模拟-场模拟方法,研究浅埋岛式站点内烟气横向流动和不同站层间的烟气纵向蔓延规律。分析烟气在隧道、站台及站厅内蔓延时烟气温度、有毒气体浓度、可见度等特征参数的分布情况;探讨了火灾时浅埋岛式站点内有效的气流组织形式,隧道排烟系统的运行模式;该研究结论有助于同类型的地铁车站的设计和运营管理。     

与体育场馆连接地铁车站大客流疏运能力计算模拟分析

突发大客流是威胁地铁车站运行的主要风险之一,为研究与大型体育场馆连接的车站在大型活动期间面对突发大客流疏导问题,利用行人仿真动力学的方法,建立地铁车站疏运模型。计算分析一岛一侧站台和一岛站台2种设计方案下的大客流疏运过程,研究客流运动特征及乘客滞留情况、疏散通道节点通过能力、公共区容纳能力、瞬时客流密度等指标,给出不同设计方案下的最大疏运能力。计算模拟结果表明一岛一侧站台时最大疏运能力为30 294人/h,站台、站厅容纳能力与运能相匹配,一岛一侧站台设计方案时,主要控制点为楼扶梯通道和站台面。计算模拟结果与理论分析结果相符,表明计算模拟方法适用于地铁大客流模拟。     

基于STEPS的地下双层岛式站台人员疏散模拟研究

本文以某地地下双层岛式站台车站为例,针对设定疏散场景使用STEPS软件分别从人群结构、疏散楼梯宽度以及疏散策略进行模拟分析,结果显示,在采取一定防火分隔的条件下,通过过轨疏散节点疏散可以减少站台人员事故疏散时间,提高疏散效率。     

深埋岛式地铁车站站台火灾时烟气蔓延数值分析

随着我国地铁的发展,未来部分地铁的发展空间属于埋深较大,经过老城区时须穿越大片房屋桩基,地质条件复杂,施工难度大,工程实施上线路和车站均需要较大的埋深。因此,深入开展深埋地铁站点火灾安全研究有助于地铁安全管理工作。笔者针对地铁深埋岛式站台火灾,利用数值模拟方法,研究深埋岛式站点内烟气横向流动和不同站层间的烟气纵向蔓延规律。分析烟气在隧道、站台及站厅内蔓延时烟气温度、有毒气体浓度、可见度等特征参数的分布情况;同时探讨了火灾时深埋岛式站点内有效的气流组织形式,隧道排烟系统的运行模式。所获的研究结论有助于同类型的地铁车站的设计和运营管理。     

导流栏杆设置对地铁岛式站台人员疏散的影响分析

为研究导流栏杆设置对地铁岛式站台人员疏散效率的影响,选取不同出口分布类型的地铁岛式站台为研究对象,基于BuildingEXODUS软件进行数值模拟,分析导流栏杆设置对不同出口分布类型地铁岛式站台人员疏散的影响.研究结果表明:A型站台在设置导流栏杆后,人员疏散时间均有所增加,导流栏杆设置长度为2,4 m时,人员疏散时间增...     

某复合型地铁车站站台防排烟方案研究

在地铁站台火灾中,机械排烟和补风对于有效排出站台烟气至关重要,地铁设计规范要求采用正压送风方式来防止烟气经扶梯和楼梯流入站厅层。对于复合型地铁站台而言,站厅层可能与其它建筑共用,建筑面积较大,难以提供足够的风压进行正压送风。本文利用性能化防火设计方法对多种站台防排烟方案进行研究,并提出了分析流程。本文还针对某实际工程案例验证了这一流程的可行性,并据此选择了一种将机械排烟和补风有机结合的防排烟方案。本文的研究工作对其它类型地铁站台防排烟方案具有参考价值。     

地铁侧式车站列车火灾排烟模拟研究

利用火灾动力学模拟方法,对地下一层地铁侧式车站列车火灾的烟气蔓延规律和排烟效果进行了模拟研究。首先生成了地铁车站的三维模型,基于通风排烟系统的事故运行方案,对列车火灾烟气扩散过程、气流组织模式和烟气参数进行了计算模拟。模拟表明：排烟系统启动后,中间隧道的两端向内形成了大于5m/s的流速,屏蔽门处流速为站台流入隧道,可有效阻碍烟气进入站台区域,烟气排放主要通过车站轨顶风口排放,烟气在500s左右进入站台,排烟系统有效减缓烟气在站台的下降时间,为列车内乘客疏散提供了可用的安全疏散时间。     

深埋地铁防排烟设计研究

地铁深埋敷设减少了对路面交通、高层建筑的影响，减少了房屋拆迁量，改善区间施工条件，但同时也对地铁站点的通风、排烟设计的安全性提出了更高的要求。文章结合广州市地铁6号线线路深埋敷设条件，对多层结构深埋车站的通风排烟系统设计进行了探讨，同时采用火灾动力学模型分别对深埋车站站台火灾、列车火灾进行了数值模拟，进而验证了防排烟设计的有效性。研究表明，深埋车站排烟系统的设计方案可以在扶梯开口处形成至少1．5m／s的向下流速；发生站台行李火灾和车站列车火灾时，排烟系统可以有效地控制烟气不向站厅蔓延，确保火灾时的站台层以上区域为无烟区和安全区；疏散楼梯间可保持微正压和无烟气进入；深埋车站排烟系统可以保证火灾时的人员可用安全疏散时间ASET大于6分钟。文章结论可为国内外类似深埋车站排烟系统提供参考。     

基于理论计算和模拟仿真的轨道交通地下车站 大客流紧急疏散能力评价及比较

在封闭的地下车站内,大客流紧急疏散能力是建筑设计和运营期间需重点关注的风险。本文选择某即将开通的地下二层岛式车站,分别采用理论计算和模拟仿真方法,评价其疏散能力能否满足相关规范要求。计算结果表明:无论采用哪种方法,远期高峰小时一列车进站后,列车及站台乘客从站台全部疏散至站厅区域时间均小于6min,符合国家标准规定。另外,《地铁设计规范》计算的疏散时间最短,《地铁安全疏散规范》计算所需的疏散时间最长,采用模拟软件计算居中,与《地铁安全疏散规范》的计算结果较为一致。     

自动扶梯运行方式对地铁站台人员安全疏散的影响

地铁车站站台人员密集,客流量大,在火灾等应急条件下对人员安全疏散有较高的要求.目前自动扶梯在地铁车站中大量应用,其运行方式(上行、下行、停运、反转)对地铁车站内人员安全疏散有较大影响.利用人员疏散网络模拟软件EVACNT7对某地铁站台层人员向站厅层疏散进行数值模拟,研究了当自动扶梯正常上行时的输送能力,并与不同人流条件下的楼梯的输送能力进行了对比,得到动态折算系数.同时也研究了当自动扶梯停运作为疏散通道使用时的输送能力,并与人流条件优化时的疏散楼梯输送能力进行了对比得到静态折算系数.还研究了下行的自动扶梯在火灾等应急条件下反转上行以降低人员疏散时间,并给出了一种下行自动扶梯反转最迟完成时间的计算方法.研究工作可以为同类地铁站台人员安全疏散设计和应急预案制定提供参考.     

视频摄像机使用平行网络安装

在本例子中,详细介绍安装网络摄像机时的电缆选择.摄像机将安装在工作区,并在主跨节点的计算机上观看,并可以选择通过Internet观看.     

Implementing a safety culture in a major multi-national

This paper reports on the implementation of an advanced safety culture in a major oil and gas multi-national. The original proposal came from the company after it had become clear that expectations had been raised after the successful implementation of Health, Safety and Environment (HSE) Management Systems subsequent to the Piper Alpha disaster. The proposal made by the company, to develop a workforce intrinsically motivated for HSE, was operationalised as the development of an advanced safety culture after a review of the literature on motivation. The model used was the HSE Culture Ladder that had become the industry standard accepted by the OGP (International Association of Oil and Gas Producers). This model was intended to show that there were considerable opportunities for improvement even after HSE-MS had been implemented and that the more advanced cultures were ones people felt were desirable and achievable for themselves. Once top management had provided the initial support for the development of a more advanced safety culture, a number of supporting tools were developed, under the Hearts and Minds brand, and a strategy for implementation was developed that relied more on bottom-up ‘pull’ rather than top-down ‘push’ – the standard implementation model for new initiatives. The tools were designed to provide a clear direction, a road map to an advanced culture defined in terms provided by people within the industry, to support lasting changes in attitudes and beliefs, to promote an increased feeling of control when solving HSE-specific problems – all components of a more advanced culture. The tactics employed, using a pull rather than a push approach, had to allow for local variation within the general limits set by the strategy that eventually became a mixed top-down and bottom-up approach. Next there is a discussion of the current status and the lessons to be learnt from the implementation so far: moving away from command and control is hard for large organizations; such programs have to be driven by different performance indicators; managers have to learn to disperse their control; it is essential to communicate both successes and failures. Finally there is a discussion about the respective roles of academia and the industry in such endeavours, the requirement to concentrate on more than a single cultural characteristic such as reporting, and the difficulties of evaluating such programs in a worldwide environment that is continuously changing.     

Chlorine leakage from bonnet of a valve in a bullet—a case study

This paper deals with the accidental release of chlorine from bonnet of a valve in a bullet installed in a chloro-alkali industry, and the probable causes of the accident and the ensuing sequence of events. Emergency procedures are also discussed. Finally, in the conclusions reached at some useful recommendations, which has been drawn for industrial facilities handling chlorine.     

一起化肥厂爆炸事故的原因分析

某县化肥厂合成车间分析室突然发生爆炸,当班的2名化验员当场死亡,经济损失较大.爆炸冲击波将整个钢筋水泥(20m2)的分析室夷为平地,一块重约70kg的砖垛被抛至30m以外;离爆炸中心方圆60m以内的建筑物玻璃全部震碎.     

某酒吧特大火灾场景的数值重构

基于FDS对某酒吧特大火灾事故进行数值重构研究,再现了火灾发生、发展的全过程,并与火灾现场勘查报告、现场照片比对;与此同时,详细地分析和研究了火场中典型部位的温度、CO浓度及FED指数等细节性参数的发展变化趋势,结果表明,模拟中的火灾蔓延过程、烟气填充过程、热释放速率、温度等参数与火灾现场勘查笔录和电子物证基本吻合,可与火灾调查其它证据相佐证,完善火灾调查结论,为进一步研究和改善此类场所的防火措施和灭火救援方案提供了依据。     

Ignition of a dust layer by a constant heat flux

In real conditions, the surface temperature of an equipment enclosure covered with a combustible dust layer can significantly rise due to insulating properties of the dust layer. To assess this effect, the measurements of minimum ignition temperature of dust layer at constant temperature of the heated plate t_{t min} (standard method) and the same ignition temperature at constant rate of heat generation t_{h min} for two coal dusts were made. Dust layers of thickness between 5 and 50 mm were tested. For each dust, t_{t min} was higher than t_{h min} for every tested thickness of the layer. The difference was biggest for thin layers and decreased with increase of the layer thickness. The results suggest a deficiency of the standard procedure of measuring minimum ignition temperature of a dust layer.     

Dynamic model for a heat exchanger tube rupture discharging a high-pressure flashing liquid into a low-pressure liquid-filled shell

Shell-tube type heat exchangers are often used to exchange heat between a high-pressure fluid and a low-pressure fluid. The pressure difference between these two fluids could be significantly high. In the event of a partial or full rupture of a tube, a problem may arise in that a transient pressure rise phenomenon could occur due to the flashing of the high-pressure sub-cooled fluid in the tube into the low-pressure shell, which may cause the shell to rupture with subsequent damage to equipment. This paper presents a dynamic model to describe the transient phenomenon occurring on the shell side following various scenarios of tube rupture. The spatial and temporal aspects of the flow transients along the pressure safety valve riser are accounted for by solving the one-dimensional continuity and momentum hyperbolic partial differential equations as applied to the liquid-filled riser. The dynamics of the attached piping system are also accounted for via two mechanistic models; the first is based on an inertial-resistive assumption of the fluids in this system, while the other is based on the assumption of anechoic perturbations passing through a long section of the attached piping. The latter is justified in cases where the attached piping is long enough such that reflections from the downstream end do not interfere with transients occurring in the shell during the initial phase of fluid flashing into the shell side following rupture. The various phases of this phenomenon are described, however the paper focuses on the initial phase of the phenomenon during which shell overpressure may be encountered. The model is applied to two ethylene heaters in tandem; the first uses propylene on the shell side to heat the ethylene on the tube side, while the second uses methanol, also on the shell side. The ratio between the shell design pressure to the tube design pressure in these two heaters are 0.169 and 0.154, respectively, hence the motivation to accurately model the transients involved in this phenomenon. The practical aspects and discussion around techniques to alleviate potential overpressure scenarios due to tube rupture are emphasized throughout the paper.     

Application of mindfulness-based stress reduction to a stress management intervention in a study of a mining sector company

Purpose. The aim of this article was to check whether mindfulness-based stress reduction (MBSR) is an effective intervention in reducing work-related stress in the case of workers in a copper mine. Methods. Sixty six employees were randomized to the experimental group (32 participants) or to the control group (34 participants). Work-related stress was measured using the job content questionnaire (JCQ) and mental health was measured using the general health questionnaire (GHQ-28) Experimental manipulation was 40-h MBSR training. Results. Multivariate repeated-measures analysis of variance revealed a significant increase of JCQ decision latitude (F?=?17.36, p?<?0.001) and social support (supervisor F?=?9.00, p?<?0.004; coworker F?=?5.61, p?<?0.020), and a significant decrease in GHQ-28 anxiety (F?=?5.28, p?<?0.079) and depression (F?=?3.95, p?<?0.048) due to the intervention. Conclusions. The study confirms that MBSR can be effective in reducing stress resulting from the external risk (and/or imagined fear) of losing one’s health or life. The use of MBSR could be recommended in health and safety activities in difficult and dangerous work conditions, such as mining, to promote workers’ well-being.     

Application of a predictive safety model in a combustion testing environment

A predictive safety model for accident prevention and system failure, called Continuous Hazard Tracking and Failure Prediction Methodology, is applied at the Marshall Space Flight Center's promoted combustion test chamber. It combines the underlying principles of work sampling, control charts, and multivariate analysis. The sampling is performed to observe the occurrence of conditions which may be becoming hazardous in a given system. These building blocks of hazards, which we have called dendritics, could result in an accident, system malfunction, or unacceptable risk conditions. The data collected is plotted to generate the appropriate control chart, which depends on the characteristics of the given system and the protection desired. Based on the pattern of the control chart, a system ‘under control’ is not disturbed whereas a system ‘out of control’ is investigated for potential conditions becoming hazardous. Then appropriate steps are taken to eliminate or control these conditions in order to maintain a desired safety status of the system. The continuously running characteristic of this model allows for the verification that the corrective measures taken to ameliorate the ‘out of control’ conditions were satisfactory or whether more proactive action is required. The results provided by the predictive model were validated with historical safety data.     

Thermal effects of a sonic jet fire impingement on a pipe

Although the effects of jet fires are often limited to rather short distances, if their flames impinge on a pipe or a vessel collapse can occur in very short times. In such cases, the heat flux on the affected equipment is very high and wall temperature can increase very rapidly. This can happen in parallel pipelines, if a release occurs and impinges on another one. Nevertheless, jet fire impingement has been scarcely studied. In this communication the results obtained from an experimental set-up are presented. Sonic jet fires impinged on a pipe containing stagnant air or water. The temperatures of the flames impinging on it were measured for the worst case (flame front-bright zone), as well as the evolution with time of the pipe wall temperature at different locations. Initial temperature increases up to around twenty °C/s were registered for the air inside, with maximum values of up to 600 °C reached in 2.5 min, and 800 °C in approximately 9 min. In the case of pipe containing water, in the zone of the wall in contact with the liquid the heating rates were much lower, the maximum temperature reached being up to approximately 150 °C. From the temperatures of the jet flames and of the pipe, the heat fluxes reaching the pipe and the corresponding heat transfer coefficients were obtained. The results obtained emphasized that safe distances are essential in pipelines, together with fire proofing and other safety measures.