Effects of the ventilation duct arrangement and duct geometry on ventilation performance in a subway tunnel

This study has investigated numerically the effects of the ventilation duct number and duct geometry on duct ventilation performance in a subway tunnel. A three-dimensional numerical model using the dynamic layering method for the moving boundary of a train, which was validated against the model tunnel experimental data in a previous study, is adopted to simulate train-induced unsteady tunnel flows. For the tunnel and subway train geometries that are exactly the same as those used in the model tunnel experimental test, but with the ventilation ducts being connected to the tunnel ceiling, the three-dimensional tunnel flows are simulated numerically under five different ventilation duct numbers and two different duct geometries. The numerical results reveal that: (1) for a given total area of openings, the ventilation duct number has little influence on the total mass flow of the air sucked into the tunnel through the ventilation ducts while the total mass flow of the air pushed out of the tunnel through the ducts increases remarkably with the increase in the duct number; (2) with the increase of the distance between a specific ventilation duct and the tunnel inlet the suction mass flow through the duct decreases significantly while the exhaust mass flow through the duct increases greatly, i.e., the location of a specific duct has a strong impact on the total suction and exhaust mass flows through the ventilation duct; (3) as the linkage angle between the tunnel ceiling and the upstream side wall of a duct is changed from 90° to 45°, the size of the re-circulation area inside the duct is much reduced when the train approaches the duct and thus the amount of air pushed out of the duct is greatly increased (i.e. the exhaust effect through the duct is remarkably strengthened).     

明月山隧道通风竖井施工技术

结合明月山隧道的工程概况,介绍了该隧道通风竖井施工的设备,详细地阐述了该通风竖井的施工方案及方法,并提出了施工注意事项,从而完善隧道通风竖井施工工艺,积累隧道工程通风竖井的施工经验.     

通风斜井与小半断面导洞在隧道施工中的应用

结合雁门关隧道工程地质条件，介绍了通风斜井方案以及小半断面导洞优先贯通的掘进方法在施工中的应用，指出两种方法的采用加快了工程进度，取得了良好的社会及经济效益。     

泰宁隧道大坡度斜井施工关键技术研究

以目前福建省在建的泰宁隧道为例,介绍了大坡度斜井施工过程中的成功经验,包括对掏槽方式的优化,运输组织的合理设计,设置避险车道及避险平台等,可为今后类似工程提供有力指导。     

秦岭终南山公路隧道3号竖井反井法施工技术

阐述了秦岭终南山公路隧道3号通风竖井采用反井法施工,用BMC400反井钻机进行了竖井施工,充分利用了机械配套设施,保证了深竖井施工工期,通过介绍竖井施工方案、施工方法,指出了特长隧道深竖井施工的发展方向。     

Numerical analysis of different ventilation schemes during the construction process of inclined tunnel groups at the Changheba Hydropower Station,China

During the excavation process of underground caverns, the rational selection of the ventilation scheme is very important for the safety and health of construction workers. The flood discharge tunnel groups at the Changheba Hydropower Station are selected as a case to study the design of ventilation schemes in inclined tunnel groups; these groups are characterized by a gradient of approximately 10% and a complex intersecting relationship among the tunnels. The Computational Fluid Dynamics (CFD) method is used to simulate the fluid dynamics in tunnel groups when different ventilation schemes are employed. Four ventilation schemes with the same duct at different positions along the transverse section are formulated, and the scheme approaching the right side with most of the construction adits is adopted in engineering after a comparative analysis, as it offers a well-distributed velocity field and sufficient security distance. The study reveals that flow vortices appear in the tunnels with a long axis length ranging from 5 m to 20 m; the observation that the flow velocity on the transverse sections is away from the heading face indicates that a low-velocity area is always present in the vicinity of an air duct, and the security distance on the upstream side is 60% shorter than on the downstream side with the same air-blower when the tunnels have a 10% gradient. In addition, when the excavation distance rises 200 m, the ventilation condition in the tunnels, especially in the areas around tunnel intersections, is greatly improved by the completion of pilot tunnels and shafts in advance.     

浅谈地铁隧道中通风排烟存在的问题及对策

针对目前国内地铁站台、隧道设置的通风和排烟设施的情况,分析了地铁站台、隧道的通风和排烟存在的问题,并提出了整改措施,指出科学设置防排烟设施以及事故状态下合理进行防排烟处置,对于减少人员伤亡和财产损失具有重要意义。     

长大铁路隧道施工通风技术探讨

在总结钻爆法无轨运输压入式、排风式和巷道式通风技术经验的基础上,通过对燕山隧道5号斜井进双正洞同时施工的两个阶段通风系统设计和布置,达到了提高通风效果和改善隧道施工环境的目的。     

谈贵广铁路天平山隧道2号斜井的动态设计

以新建贵广铁路为例,介绍了天平山隧道2号斜井软弱围岩大变形试验段的动态设计的原理与方法,实现软弱围岩大变形控制,降低了施工安全风险,提高了工程进度,达到预期目的。     

CD法在观音堂隧道斜井挑顶施工中的应用

结合观音堂隧道的工程概况,提出了隧道斜井挑顶施工的总体方案,对斜井进正洞的主要技术参数进行了说明,详细地介绍了CD法在观音堂隧道斜井挑顶施工中的施工方法及施工要点,以供读者参考。     

深基坑开挖对临近地铁隧道影响分析

根据经验利用岩土有限元分析软件plaxis对临近地铁深基坑的开挖及支护进行了数值模拟,分析了基坑开挖对地铁隧道的沉降及变形影响,并提出了合理的保护措施,以确保地铁隧道的安全,为后续类似工程提供有益借鉴。     

乌鞘岭隧道九号斜井机械管理统计分析

对某隧道长大斜井施工的机械设备配置进行了说明,并对配件、用电、租赁等费用作了分析,设备运用情况证明,长大斜井的施工需要充分准备,精心安排,以期降低成本;先进设备的使用是保证施工的关键因素。     

五凤煤矿高瓦斯井巷安全快速施工技术研究

总结了开拓方式整体布置、掘进工艺、施工组织、掘进设备等方面的施工要点,以提高煤岩巷道的连续掘进技术水平,改进生产工艺,优化劳动组织,实现煤岩巷道安全高效掘进。     

地铁盾构区间隧道水平近距离洞内加固技术

以苏州轨道交通一号线桐泾路站-广济路站区间为背景,详细介绍了在盾构隧道近距离施工的情况下采取的洞内加固和保护措施,并通过各种监测表明,这些措施能够满足工程实际的需要。     

双幕墙高层办公楼通风效果风洞试验研究

针对杭州市一双幕墙高层办公楼工程实例,采用整体刚性模型风洞试验和节段刚性模型流场试验相结合的方法,研究了廊道式双幕墙建筑的通风效果及其评判标准,提出了双幕墙建筑通风换气时间的计算方法,探讨了风压作用下双幕墙空腔和百叶窗的气流组织方式,验证了拔风井在双幕墙体系中的作用。     

Numerical modeling of the flow conditions in a closed-circuit low-speed wind tunnel

A methodology for numerically simulating the flow conditions in closed-circuit wind tunnels is developed as a contribution to the general philosophy of incorporating Computational Fluid Dynamics (CFD) in wind tunnel design and testing and to CFD validation studies. The methodology is applied to the full-scale Jules Verne climatic wind tunnel in which experimental data have been obtained. Due to the specific features of this closed-circuit wind tunnel, the conventional CFD modeling approach, in which only the flow in the wind tunnel test section is modeled, is inadequate. To obtain accurate results the entire wind tunnel has to be modeled. In the numerical closed-circuit wind tunnel, the conventional flow inlet and outlet are replaced by a single “fan boundary condition”. Special attention is given to the theoretical background and the practical implementation of this type of boundary condition in the CFD model. The numerical model is validated for the case of an empty wind tunnel and for the case in which a block-type building is placed in the test section. It will be shown that this methodology can generally reproduce the wind tunnel measurements of mean velocities with an error equal to or less than 10% despite the occurrence of multiple flow separations upstream of the test section. This provides perspectives for the future use of this methodology as a tool for wind tunnel design and testing and for CFD validation purposes.     

广州浅岩区紧邻地铁隧道某建筑基坑优选分析

为确保广州浅岩区紧邻地铁隧道某建筑基坑的顺利实施,同时保障地铁安全运营,对基坑支护结构形式进行了探讨,并采用平面和三维数值手段分析了基坑开挖过程中采用附加支撑后对地铁隧道的影响。分析结果表明,采用附加支撑后,双排桩支护结构结合中心岛法开挖可有效控制支护结构和地铁隧道的位移,并减少工程成本。     

高强高性能混凝土在冻结井壁中应用研究

对冻结井井壁高强高性能混凝土配合比进行了试验研究,利用高效减水剂降低水灰比,同时通过"三掺"技术,不仅满足了混凝土的高强、早强要求,对混凝土的后期强度、抗渗性、耐久性也有所改善,对今后冻结井井筒混凝土的配制具有指导意义。     

水电站无压尾水洞引风热湿交换特性的现场测试

对映秀湾水电站无压尾水洞引风过程中的室外空气温湿度、尾水洞出口空气温湿度、尾水进出口温度、引风量等参数进行了测试。测试结果表明,夏季运行时无压尾水洞对引入空气有良好的降温除湿效果;在无压尾水洞足够长的条件下,尾水洞末端引风参数主要受尾水温度的影响,而受室外空气参数的影响很小,尾水洞出口空气接近对应尾水温度的饱和状态。