Rock Pressure on Tunnel with Shallow Depth in Geologically Inclined Bedding Strata

Introduction Ithasbeenpracticallyprovedthatthecorrect analysisandcomputationoftheloadsinducedby rockmassandpressuresexertedontunnelstructureare prerequisitestomakearationalstructuredesignand ensurethesecurityoftunnelingroundstrata[1-5].Whenatunnelistobede…     

Finite element analyses of corroded pipeline with single defect subjected to internal pressure and axial compressive stress

This paper describes the application of finite element method (FEM) and the development of equations to predict the failure pressure of single corrosion affected pipes subjected to internal pressure and axial compressive stress. The finite element analysis (FEA) results were verified against full-scale burst tests and theoretical calculations. Material non-linearity, which allow for large strains and displacements, were considered. In addition, true UTS instead of engineering UTS was used to determine the point of failure. The pipes used in the FEA was modelled based on API 5L X52 modified steel with a length of 2000 mm, a nominal outer diameter of 300 mm, and a nominal wall thickness of 10 mm. The results obtained from FEA were compared to that of existing comprehensive corrosion assessment method, known as DNV-RP-F101. Six equations, utilizing the Buckingham's π theorem and multivariate non-linear regression techniques, were developed for predicting the failure pressure of corroded pipeline with single defect subjected to both internal pressure and axial compressive stress. These equations provide improved failure pressure predictions with good margins of errors (less than 10%).     

排气管内二维非定常流动的计算研究

为了优化设计排气管形状，本文研究了柴油机排气管内二维非定常湍流流动的计算，排气管与气缸交接处的边界条件由实验结出，湍流模型采用k－ε模型。计算了一根3缸模型排气管内排气流动变化，计算结果与实验结果吻合良好。该研究对排气管的形状设计有一定的应用价值。     

港口集群的内部竞争

港口集群以产业集群理论为基础,它是研究港口竞争力问题的一种新的理论方法,而集群内部竞争对于提高一个港口的整体竞争力非常有利,它们是加强港口集群竞争力的一个重要因素。本文首先将产业集群的概念应用到港口中来界定港口集群和内部竞争,提出了实施路径来鼓励内部竞争,探讨了如何提高港口集群的效益。     

城市轨道交通站台自动扶梯服务水平研究

通过对西安市地铁2号线钟楼站晚高峰时段,站台至站厅层上行扶梯进行的人工观测与视频采集,在自动扶梯处区域划分及行人特性分析基础上,得到速度-密度拟合曲线。以人均占据面积为标准得出适用于西安市城市轨道交通的自动扶梯服务水平分级。结果表明,本分级方案对我国城市轨道交通站点运营中的实际情况具有较强的针对性,并具有一定的理论意义和实用价值。     

不同形状土工合成材料的内力分析与加筋作用研究

对正方形、等边菱形、正六边形的土工格网的内力传递进行了分析计算,并以六边形土工格网和单、双向塑料土工格栅为例,对加筋土工合成材料在填土中所起的加筋作用作了探讨与分析,为土工合成材料的生产和使用提供了依据和指导.     

Hazard perception test development for Lithuanian drivers

Hazard perception tests may not be transferable between different countries, due to differences in traffic culture and infrastructure. Therefore, different instruments might be necessary for assessing hazard perception in various countries. The aim of the current study was to develop the Lithuanian hazard perception test based on static traffic images and test its psychometric properties. Thirty-four experienced drivers participated in a pilot study, and 125 drivers with diverse driving experience took part in the main study. The final test contained 27 static traffic scenes and the participants were asked to respond if they saw a hazard or not. Results demonstrated that the test has satisfactory internal consistency and test-retest reliability. It differentiated between inexperienced and experienced drivers, and between those experienced drivers who had less than three or more than three crashes in their driving history. The test has sufficient psychometric properties for research; still further development is needed in order to apply it for individual testing and decisions about licence provision.     

火电厂化学吸收CO2捕获工艺的应用与能耗分析

从火力发电厂烟气特性出发,分析了化学吸收CO2捕获工艺流程,评估了醇胺吸收剂和改进型吸收剂的特点及适用性,总结了吸收剂在国内外CO2捕获示范工程中的应用情况,提出了化学吸收工艺能耗分析参数体系,通过工程和理论研究两个路径对化学吸收CO2捕获工艺的能耗水平进行了分析.分析结果表明化学吸收工艺吸收剂以胺和混合胺为市场主导,CO2捕获吸收剂的再生能耗一般介于3.0～4.2GJ/t之间.     

马蹄形隧道初期支护内力反演分析的理论研究

隧道开挖过程中,混凝土支护结构的内力分布表现出特有的动态变化特征,对施工环境下隧道支护结构的内力分布特征进行研究并对其薄弱部位进行预判是保障隧道施工安全的重要手段之一。文章将隧道弧段和边墙段初期支护分别视为弹性地基曲梁和直梁,基于初参数法和围岩压力量测,从理论上推导了马蹄形断面隧道初期支护内力计算的反演表达式;结合某隧道围岩压力的实测数据,反演了初期支护的内力分布。初期支护内力实测数据和反演分析结果对比分析表明,所提出的马蹄形隧道初期支护内力的理论反分析方法切实可行,可为隧道初期支护设计和施工工艺的优化提供理论依据。