嘉陵江特大桥深水桩基施工关键技术探讨

嘉陵江特大桥主墩处于季节性流域的河道中,桥梁钻孔桩施工受洪水影响较大,地质清孔较为复杂,在施工过程中不确定影响因素较多,文章针对该工程区域特殊地质和水文情况,对水中桩基施工的关键技术进行了研究。     

桥梁空心高墩动力特性及风振响应数值模拟分析

高耸结构的抗风性能是一个重要的研究课题。为了研究桥梁空心高墩的动力特性以及抗风性能,文章采用有限元法建立空心墩的三维模型,分析了在风荷载作用下桥梁空心高墩墩顶及墩底的位移与加速度变化情况。所得结论可为桥梁空心高墩的抗风设计提供参考。     

岩溶地区桥梁桩基施工及质量控制探讨

以地质条件较为复杂的某桥梁桩基工程为依托,提出了其10#主墩承台桩基础优化施工方案,并基于此方案进行了桩基础施工过程及质量控制的分析,分析表明,岩溶注浆和溶腔回填混凝土是本桥梁桩基施工质量控制的关键环节。10#主墩承台桩基础施工结束后低应变反射波法检测结果表明,本桥梁桩基施工质量良好,岩溶基础加固效果显著,且本工程施工方案优化及施工技术应用对类似工程有借鉴参考价值。     

城市高架桥跨铁路段桥墩设计

介绍了济南零点立交至燕山立交高架桥特点,根据特殊的地理位置布置桥梁结构,阐述了门式墩设计的基本思路,指出了在设计中应注意的问题及解决方法。     

浅谈特殊地质条件下的深水承台施工

水中基础因为是隐蔽工程,不可预见因素较多,因而不同地质条件下的水中基础施工已经成为大型桥梁施工中的关键技术。文章结合绵阳涪江特大桥卵石地质条件下深水承台施工实例,从基坑开挖、钢围堰拼装与下沉、水下混凝土封底、钢围堰内抽水、钢围堰壁体拆除等方面,介绍了采用单壁钢围堰技术进行特殊地质下深水基坑施工的方法,并总结了施工技术经验,为类似条件下的桥梁水中基础施工提供参考。     

烟溪沟特大桥94m薄壁空心墩翻模施工技术

薄壁空心墩一般设计于比较高的桥梁墩位中，施工难度较大。文章结合烟溪沟特大桥94m薄壁空心墩的施工实践，从空心墩模板设计、翻模施工工艺、施工要点及安全保证措施等方面阐述了翻模施工技术的具体应用，为同类施工提供参考。     

不同联长双柱墩桥梁抗震性能影响分析

地震高烈度区桥梁抗震总体设计决定着桥梁建设的安全性。通过有限元计算分析不同联长、墩高、墩柱截面形式对桥梁总体抗震性能的影响,总结出对中等标准跨径双柱墩桥梁抗震有利的分联跨数、墩高及截面形式,为高烈度区桥梁总体方案制订提供参考。     

溪门口大桥水中墩施工技术

本文介绍了溪门口大桥8号墩的施工过程，在此墩基础的施工中，根据墩位处的地质、地形情况，选用了有底钢套箱围堰，实践证明，所采取的措施是行之有效和切合实际的。     

岩溶强发育区桩基施工技术研究

针对柴河特大桥岩溶强发育区桩基施工特点,以12#主墩桥梁桩基施工为例,对岩溶强发育区桩基施工方法及特点进行阐述,重点对地质核查、施工准备、外钢护筒设置和冲击钻孔施工等流程进行系统说明。研究成果为岩溶地区桥梁桩基施工提供了参考。     

新技术新工艺

西部项目“沪蓉西龙潭隧道特殊地质条件下的关键技术研究”破解特殊地质隧道建设难题 日前，历时6年的西部项目“沪蓉国道主干线龙潭特长隧道特殊地质条件下的关键技术研究”通过鉴定。鉴定专家认为，该项目研究成果总体达到国际领先水平。     

三维有限元强度折减法在堤坝边坡稳定分析中的应用

文章针对二维有限元强度折减法的局限性,提出采用三维有限元强度折减法应用于边坡稳定分析,并结合某复杂地形的回填堤坝工程进行边坡稳定性评价。结果表明：对于复杂地形情况下边坡稳定计算,采用三维有限元强度折减法能反映工程的实际情况,计算结果是合理的。     

A continuous approximation model for time definite many-to-many transportation

Time definite freight transportation carriers provide very reliable scheduled services between origin and destination terminals. They seek to reduce transportation costs through consolidation of shipments at hubs, but are restricted by the high levels of service to provide less circuitous routings. This paper develops a continuous approximation model for time definite transportation from many origins to many destinations. We consider a transportation carrier serving a fixed geographic region in which demand is modeled as a continuous distribution and time definite service levels are imposed by limiting the maximum travel distance via the hub network. Analytical expressions are developed for the optimal number of hubs, hub locations, and transportation costs. Computational results for an analogous discrete demand model are presented to illustrate the behavior observed with the continuous approximation models.     

A hierarchical rule-based land use extraction system using geographic and remotely sensed data: A case study for residential uses

Lack of detailed land use (LU) information and of efficient data gathering methods have made modeling of urban systems difficult. This study aims to develop a hierarchical rule-based LU extraction system using very high resolution (VHR) remotely sensed imagery and geographic vector data. Land cover information extracted from remote sensing and several types of geographic data from the study area, City of Fredericton, Canada, are fused into a comprehensive database, in order to develop a sophisticated LU Extraction Expert System (LUEES). This paper illustrates how the proposed LUEES though a case study for residential uses in the study area. Morphological (individual-based) analysis at the building-level is carried out through a step-wise binary logistic regression model, which differentiates residential and non-residential buildings and results in an overall accuracy of 93.1%. The results derived from morphological analysis are then subject to a post-correction process using a spatial arrangement analysis, in order to further mitigate the misclassification issues arising from the morphological analysis. In this regard, Gabriel Graph connectivity examines the spatial structure and arrangements of urban features concerning different LU types. It is found that the spatial arrangement analysis further enhances the residential LU classification accuracy, which gives rise to an overall accuracy of 97.4%. It is believed that, equipped with such a powerful LU data collection tool and resulting detailed/accurate LU data, urban planners/modelers should be able to more reliably and precisely represent/predict economic interactions, activity locations, space and housing developments, business expansion, and trip patterns.     

Logistic performance evaluation of provinces in Turkey: A GIS-based multi-criteria decision analysis

Logistics performance evaluation of provinces is considered in this study. To do so, a three-step solution approach is developed: (i) determination of 16 geographic and economic indicators, (ii) using geographic information system to assign a logistics score and (iii) prioritizing the indicators and ranking the provinces using multi-criteria decision analysis tools. Proposed methodology is applied to 81 provinces in Turkey as a case study. Results show that the provinces of Istanbul, Izmir, and Hatay are the pioneers. The proposed methodology provides the ability to analyze the impacts of indicators on logistics performance and create a logistics performance map of countries.     

A study of feasibility and potential benefits of organised car sharing in Ireland

In this study, the market potential of car sharing has been evaluated using multiple alternative scenarios which examine the geographic, financial and environmental factors influencing car sharing adoption. The scenarios are applied to the available and collected travel information of the Irish population to estimate the potential impact of introducing car sharing in Ireland. The analysis identified that car owners who travel predominantly on alternative modes, could make significant cost and CO₂ savings through car sharing. A reduction of yearly CO₂ emissions of 86 kt is readily achievable through car sharing, with reductions up to 895 kt possible with appropriate policy and financial support. These figures are comparable to other measures proposed under the Irish National Climate Change Strategy.     

基于ERDAS和ArcGIS的数字管道系统的设计与实现

以中石化集团公司甬沪宁长输油管道数字化项目为背景,以地理信息系统软件ArcGIS、遥感信息处理软件ERDAS为研究工具,分析了数字管道的数据模型,确定了数字管道系统的设计思路。通过遥感信息处理软件ERDAS提取甬沪宁长输油管道的遥感数据,以管道的遥感数据和地形图为基础,获得管道及其经过区域图像和地理信息。在此基础上,通过与GIS系统的整合,建立了数字管道系统。应用表明,数字管道系统有效地提高了管道信息管理的效率。     

From e-bike to car: A study on factors influencing motorization of e-bike users across China

Household car ownership has risen dramatically in China over the past decade. At the same time a disruptive transportation technology emerged, the electric bike (e-bike). Most studies investigating motorization in China focus on macro-level economic indicators like GDP, with few focusing on household, city-level, environmental, or geographic indicators, and none in the context of high e-bike ownership. This study examines household vehicle purchase decisions across 59 cities in China with broad geographic, environmental, and socio-economic characteristics. We focus on a subset of households who own e-bikes and rely on a telephone survey from an industry customer database. From these responses, we estimate two three-level hierarchical choice models to assess attributes that contribute to (1) recent car purchases and (2) the intention to buy a car in the near future. The results show that the models are dominated by household characteristics including household income, household size, household vehicle ownership, number of licensed drivers and duration of car ownership. Some geographic, environmental and socio-economic factors have significant influences on car purchase decisions. Only two city-level transportation variable have an effect – higher taxi density and higher bus density reducing car purchase. Cold weather, population density gross domestic product per capita positively influence car purchase, while urbanization rate reduces car purchase. Because of supply heterogeneity in the data set, described by publicly available urban transportation data, this is the first study that can include geographic and urban infrastructure differences that influence purchase choice and suggests potential region-specific policy approaches to managing car purchase may be necessary.     

On the calibration of the combined distribution-assignment model

We consider a model which combines gravity model trip distribution and equilibrium assignment. This model contains a free parameter which must be fixed using supplementary information, that is, the model must be calibrated. It is natural to ask which supplementary information is sufficient to determine the free parameter. We show here that under very weak hypotheses each of the quantities, the entropy H or the total assignment cost F, is alone sufficient to determine the free parameter. In contrast, it is shown by means of a counterexample that even under very strong hypotheses, the total cost C is not sufficient.     

地质稳定与生态环境的相互影响及评价

文章基于灾变链式理论,阐述了地质稳定和生态环境的相互依存关系,分析了地质灾害对生态环境造成的效益损失,提出运用模糊综合评判法对生态环境影响下的地质稳定性进行分析,并将该方法运用于重庆长寿区一滑坡实例,分析了该滑坡地质稳定性及其所造成的生态效益损失。     

酸性条件下国内外用管情况及金属防腐分析

在酸性条件下,管道腐蚀相当严重,产生的危害也很大.因此,进行金属防腐分析具有重要意义.文中对国内外天然气管道的使用情况进行了介绍,并对这些管道的材质以及特点进行了说明.针对腐蚀发生的不同原因,介绍了采用涂防腐绝缘层、阴极保护和连接线等有效延缓管道腐蚀的防护措施,并分析了各自的优缺点.实际上,既经济可行又有效的防腐方法是...