公路隧道近距离下穿电力管线施工技术研究

为解决杭州市香积寺路西延工程盾构段下穿220 kV半霞线线、半霞线电力管沟横穿东侧明挖段隧道基坑(4#工作井)及燃霞、燃湾线电力管沟与中间明挖隧道基坑呈“L”形交叉等施工难题,首先,通过对盾构施工的影响范围、地表隆陷变化规律以及电力管沟对地表变形适应能力评估的研究,采取优化掘进参数、控制泥水压力、掘进速度、出渣量、盾构纠偏量以及同步和二次注浆等措施对管线进行保护;其次,为降低施工难度,现场采用工字钢横梁顶托混凝土电缆沟和钢筋混凝土盖板托撑电力管沟的就地保护措施对管线进行保护.对220 kV电力管线采取了合理的施工保护措施之后,工程隧道基坑得以顺利开挖,盾构按时始发,既节省了费用,又缩短了工期,同时也为今后类似工程的施工提供了参考.     

A pseudofield model approach to simulate compartment-fire phenomena for marine fire safety design

In order to prevent the spread of marine compartment fires, it is necessary to understand the governing factors or characteristics of fire-spread phenomena. We present a pseudofield model approach to this problem. We first described a field model of turbulent heat convection based on a standard k – turbulence model. Two-dimensional numerical simulations of a two-linked compartment fire were carried out in order to predict the turbulent convection flow induced by the heat released from the fire. Then a more complicated fire-spread problem of multilinked compartment fires was analyzed by means of a zone model, in which the amounts of oxygen consumption and gas generation were solved by a gas-balance equations system. The effect of threshold conditions on fire propagation and the effect of the thickness of the heat insulation were investigated with numerical simulations.     

A study of the environmental impacts of intelligent automated vehicle control at intersections via V2V and V2I communications

This article presents a novel intersection traffic management system for automated vehicles and quantifies its impact on fuel consumption and greenhouse gas emissions of CO₂ relative to traditional traffic signal and roundabout intersection control. The developed intelligent traffic management (ITM) techniques, which are based on a spatiotemporal reservation scheme, ensure that vehicles proceed through the intersection without colliding with other vehicles while at the same time reducing the intersection delay and environmental impacts. Specifically, the spatiotemporal reservation scheme provides each vehicle a collision-free path that is decomposed into a speed profile along with navigational instructions. The integration of the developed microscopic traffic simulator with instantaneous emission model, provides improved assessments of the environmental impact of traffic control strategies at intersections. The simulator architecture integrates several ITM algorithms, vehicle sensors, V2V/V2I communications, and emission and fuel consumption models. Each vehicle is modeled by an agent and each agent provides information depending on the specific vehicle sensors. The ITM system is supported by V2V and V2I communications, allowing the exchange of information among vehicles and infrastructure. The data include the estimated vehicle position and speed. Compared with traditional traffic management techniques, the simulation results prove that the proposed ITM system reduces CO₂ emissions significantly. The research also shows that these reductions are more significant when the traffic flow increases.     

中心城区主干路改造的设计要点探讨

中心城区主干路一般建成时间较早,随着城市化进程的加快和社会经济的发展,现状市政交通、管线已不能满足沿线用户的需求;路面出现不同程度损坏,影响了行车的安全性和舒适性;沿线各类城市市政设施缺乏统一性和规范性,严重影响了道路交通和城市周边形象,制约了城市形象的提升和进一步发展.针对中心城区主干路改造的设计要点,从道路功能定位、纵断面控制、路面材料、轨道交通协调与管理、现有乔木的处理等方面进行阐述.     

IG541混合气体灭火系统在成都地铁中的应用研究

根据地下轨道交通的消防特点,结合成都地铁工程设计实例,对气体灭火系统的控制及操作方式进行深入介绍,并着重论述气体消防系统在地铁设计中的应用:从环保、安全、经济、灭火效率及对被保护对象影响等方面对七氟丙烷与IG541混合气体进行比较,具体分析两种气体环保指标ODP、GWP、ALT值和对人员安全性指标LOAEL、NOAEL、LC50值,得出IG541混合气体适合于地铁地下车站的气体灭火系统的结论。     

城市管道对于软土地基沥青路面影响分析

该文针对软土地区城市道路地下管道对于沥青路面的不利影响进行分析,采用有限元方法分析了管道周边和上部土基的模量对于沥青面层内部剪应力的影响,并与容许剪切强度进行了对比.提出必须采取合理措施增加管道周边的土基强度,从而有效地避免沥青路面的剪切破坏.     

柴油机耐压排气管段材料优选及结构优化设计分析

考虑到在保证耐压排气管段的承压能力和耐腐蚀性能的前提下尽可能降低管段的重量是潜艇柴油机排气系统耐压管段材料优选及结构优化设计的主要目标,针对多种材料配套体系和多结构设计方案,用有限元计算方法对耐压排气管段的强度分布及稳定性进行计算分析,提出材料优选和结构优化设计方案,形成柴油机排气系统耐压管段材料优选和结构优化设计准则。     

LNG及车用LNG的现状与未来分析

液化天然气(LNG)具有高效、清洁、安全等特点,目前主要应用于车用燃料、城镇燃气备用气源、发电等,涉及工、商、民用,是一种应用广泛、经济性较高的能源。目前我国天然气车分为液化天然气(LNG)车和压缩天然气(CNG)车两种,两者的本质都是天然气,区别在于生产加工的方式和存在形式。     

已建道路下方新增管廊工程总体方案若干问题讨论

针对已建道路下方新增综合管廊需求情况,通过分析管廊与已建道路下方管线接驳方式、管廊施工对已建道路保护方式、管廊穿越特殊节点处理方式等,为国内类似工程提供借鉴.     

城市新建道路工程既有地下管道保护方案研究

根据城市发展需要，城市道路建设与周边用地开发并非同步进行，工程中时常遇到建设用地下方存在既有管道的情况，一般根据管道埋深、管道规模并综合工程可行性及经济性，选取保护或迁移的设计方案。对于大型管道的保护通常采用护管桥涵或者轻质材料换填的方式，两种技术方法各有其优缺点及适用性。依托项目实际情况，探讨合理的管道迁移或保护技术方案，为类似情况的工程提供参考。