单机1200t级超大吨位步履式顶推装置液压系统研究

液压系统是步履式顶推装置最核心组成部分,通过对步履式顶推装置施工工艺分析,研究满足于步履式顶推装置各项性能指标的液压系统。通过对液压原理、执行机构动作流程、元器件选型等深入研究,使步履式顶推实现按规定施工工法完成箱梁的顶推前移。步履式顶推装置平均顶推速度约为5m/h,同墩两侧顶推同步精度<3mm,各墩之间顶推同步精度<4mm;同侧顶升千斤顶顶升或下放箱梁同步精度<3mm,完全满足步履式顶推装置的各项功能要求及精度要求     

小半径曲线混凝土连续梁步履式顶推施工技术

以朔山铁路联络线预应力混凝土连续梁顶推施工为背景,通过对拖拉顶推法和步履式顶推法的优缺点对比,确定了采用步履式顶推施工方案。详细介绍了步履式顶推装置、前后钢导梁及预埋件安装、落梁、纠偏控制、同步性控制等相关内容,叙述了小半径曲线混凝土连续梁步履式顶推的关键技术。     

步履式连续顶推施工的关键技术探讨

本文简要介绍了在桥梁多点同步连续顶推施工中,一种新的步履式顶推装置的设计及在沱江四桥主桥钢箱梁顶推工程中的应用方案。本步履式装置体积小、重量轻,采用智能控制系统及变频调速控制流量技术,可实现无级调速。该装置最大优点是:整个顶推过程中,步履式顶推装置内设滑动面,滑动面不在桥梁底部,而在滑箱与滑板之间,由于顶推力和摩擦力全部是顶推设备内力,支墩基本不承受水平载荷,对桥梁和桥墩不造成损伤。     

小循环步履式顶推钢桁梁施工关键技术与控制

针对某高速铁路134m简支钢桁梁顶推施工,改进了传统步履式顶推施工行程小的不足,提出了小循环步履式顶推施工技术,阐述了该施工技术在钢桁梁顶推施工中的优越性,分析了施工过程控制的关键点。工程实践表明:大跨钢桁梁结构采用小循环步履式顶推施工技术,能有效地保证施工精度,确保其成桥线形与设计线形一致,较好地实现了钢桁梁在整个顶推施工过程中的精细控制。     

步履式顶推系统的控制策略研究

随着国家建设的不断推进,跨线桥及跨江河域桥也日益增多,但建设过程中由于地形位置、气候、通航通车等诸多因素影响,通用的架设设备难以满足其施工要求。现采用一种步履式顶推施工工法,此工法所需的装置是一套集顶推、平移、横向纠偏于一体的新一代桥梁顶推施工装置,其施工方法是多点同步顶推移梁,装置内设滑动面,滑动面不在主梁底部,可有效保证顶推装置与主体结构的接触,改善主体结构受力,对主体结构几乎零损伤。本文主要针对该装置的控制系统的控制策略及设计算法进行研究,并结合实际工况,阐述一些关于步履式顶推的控制理论及研究方向。     

步履式顶推装置设计及应用

本文介绍了在桥梁多点同步连续顶推施工中,一种新的顶推装置步履式顶推装置的设计及在昆明跨铁路桥梁顶推工程中的应用。该装置采用三维仿真及有限元设计,是一套集顶推、平移、横向纠偏于一体的新一代桥梁顶推施工装置,具有模块化、体积小、重量轻、执行顶推循环动作准确可靠以及适应性广泛的特点。该装置最大优点是,装置内设滑动面,滑动面不在桥梁底部,在滑箱与滑道之间,这样在顶推过程中就改善了桥梁及桥墩结构的受力,对桥梁和桥墩几乎没有损伤。     

钢箱梁顶推施工过程数值模拟

为弥补杆系有限元软件在步履式顶推施工存在的不足,需要一种能模拟步履式顶推(ILM)过程的三维有限元分析方法,针对这一情况,本文使用有限元软件ABAQUS提出一种新的建模方法来模拟步履式顶推施工;通过对梁体端部的约束处理,保证梁体能如实际施工那样在重力荷载下的自然挠曲变形,使用刚体块来模拟步履式顶推支承设备,并使用参考点对顶推支承设备的约束,采用"梁不动,顶推支承设备向后移动"实现梁体在顶推设备上的顶推时滑移模拟;该模型能有效模拟梁体在施工时的受力过程,对梁体在施工中的应力分布有直观的了解,能有效预知结构在施工中可能出现的问题;使用该建模方法对后丁香一号桥的顶推过程进行分析,其分析结果与施工监测报告相符合,证明该种建模分析方法可靠可行。     

基于步履式顶推技术的钢箱梁桥施工风险评价与质量控制分析

结合某桥梁工程,对基于步履式顶推技术的钢箱梁桥施工风险评价进行介绍,并从杆件拼接、临时结构、顶推过程、落梁精度4方面提出基于步履式顶推技术的钢箱梁桥施工质量控制措施。结果表明:步履式顶推技术不仅可以提高桥梁的施工质量,还能准确地进行顶推作业。     

大跨度系杆拱桥顶推施工技术研究

以孔李淮河大桥顶推施工为工程背景,对顶推施工方案的选择和临时结构的设计进行研究分析。在梁拱之间,设置刚性内撑,以提高结构在顶推过程中的整体抗弯刚度,节约材料。应用有限元软件MIDAS和ANSYS建立有限元模型,分别按照步履式顶推施工和多点牵引式顶推施工方案,进行顶推施工的仿真分析,并对两个方案的优劣性进行对比。分析表明:从力学性能而言,两种顶推方法均满足施工过程中结构安全要求。考虑步履式顶推施工对主梁损伤小,顶推速度快等特点,推荐采用步履式顶推施工。     

杭州九堡大桥多跨连续组合拱桥步履式整体顶推技术

杭州九堡大桥主桥为3 ×210m连续组合梁.钢拱拱桥,桥宽37.7m,总重14 000多t.施工中首次采用整体顶推施工技术,210m主跨中间仅设置1座临时墩,具有顶推跨径大、悬臂长、重心高及质量大等特点,施工中采用自主研发的步履式平移顶推装置及计算机同步控制系统,完全满足组合拱桥梁顶整体受力顶推的要求.重点对"步履式平移顶推"工艺关键技术进行了介绍,对顶推控制方法进行说明.同时对多跨组合拱桥大悬臂顶推中出现的问题进行总结分析.     

浅析高速公路工程招投标中的最低评标价法

结合目前高速公路施工项目招投标活动的实际情况,阐述了最低评标价法的概念,归纳了其优点及存在问题,对完善最低评标价法提出几点策略,以期促进招标投标市场更加规范有序。     

Place-Making in Megaprojects in Melbourne

This article analyses state-led place-making practices in Melbourne. The two levels of government that influence planning in Melbourne make much of the city as ‘culturally vibrant’ and ‘creative’, and have incorporated creative city-inspired place-making principles into many layers of the planning system. An examination of the development of two mixed-use megaprojects in central Melbourne reveals however that ideals of culturally engaging public places, and indeed of creative landscapes for middle-class consumption, wither in the face of more basic imperatives for economic development. In these case studies the ‘creative city’, no matter how the idea is interpreted, has little traction either as a set of inclusive place-making principles or as a gentrification strategy. The article concludes that the creative city-inspired place-making objectives in the planning system at both state and local levels are ambiguous in their overall intents and completely unsupported by statutory controls. Such place-making objectives as are realised are the compromised results of the interplay of uncoordinated decisions, delivered at the pleasure of the developer.     

Pathogens in septage in Vietnam

Septage is widely acknowledged as a major source of infectious pathogens while disposal of septage, and the operation and maintenance of septic tanks, is not regulated in many developing countries. Twenty untreated septage and septage sludge samples were taken from Can Tho City, Vietnam to examine their pathogen content, and indicator micro-organisms. Escherichia coli and Enterococcus spp. were detected in all samples, regardless of sludge storage time. Phages were detected in 80% of samples. Salmonella spp. were detected in 70% of the untreated septage and 60% of septage sludge samples. Concentrations of phages and bacteria tested in septage sludge after many years of tank storage were much higher than the expected levels. Helminth ova were present in 95% of untreated septage samples with an average of 450 ova l^− 1, and were detected in all septage sludge samples with an average of 16,000 ova l^− 1. Twelve varieties of helminth ova were identified. More helminth ova varieties in higher concentrations were found in septage than those reported from stool samples. The varieties' frequency ranged from 10% to 50% and Ascaris lumbricoides predominated. Results show that pathogens and indicator micro-organisms, especially helminth ova, accumulate in sludge. Thus helminth ova should be considered when septage sludge is treated and used for agriculture. Proper health protection measures must be applied for people handling septage.     

在市场中实践在实践中学习在学习中进步--工程公司市场化进程的回顾与展望

近两年来，工程公司在提高市场竞争意识、推动市场化进程中做了大量工作，其中坚持走出去的方针是我们自我加压、推行加快市场化步伐的一个重要战略步骤。     

新时期广东城市化的新特点

新时期广东城市化出现以下特点:知识源导向、城市由单体向群体化发展、产业集群推动、政府主导自上而下的集约化发展、城镇化向城市化转变、由重“数量”发展向重“质量”发展的转变。     

新形势下高校强化基建财务管理的探讨

在市场条件下高校基建财务人员在加强日常财务管理的同时,必须树立起高度的工作责任心,抓好事前监督、事中监督、事后监督三个环节,全面理解、贯彻执行《高等学校财务制度》,管好用好各项基本建设资金,提高基建财务管理水平,更好地完成高校各项基建任务,以有限的投资,最快的建设速度,获得最大的投资效益。     

2005年北京办公物业市场七大趋势

趋势一:CBD区域写字楼集中放量从各区域规划方案上看,CBD区域多数项目在03～04年处于项目的报批手续及拆阶段,预计2005年正式推向市场,因此2005年CBD区域将成为北京市场供应集中的域,区域即将供应的项目有北京财富中心(二期)、金地国际花园、万达广场、SOHO尚都、万通中心、世纪财富中心、怡禾国际中心、光华国际等。除去未知项目,2005CBD写字楼办公面积的供应量为60万平方米左右。中关村区域经过一段时间的集中供后开始逐步放缓,2005年供应的体量相对较大的项目有中关村金融中心、新中关。金街区域可能开盘的项目只有2个:英蓝国际中…     

浅谈我国工程项目建设成本控制存在的问题

结合目前我国施工企业工程项目成本管理现状,对工程项目成本管理过程中存在的问题进行了较详细的分析,并提出了一些解决问题的办法,以做好项目成本控制工作,进而增强企业经济实力。     

Variation in property taxation in Tulsa

Conclusions It may be reasonably concluded from this study that the range of variation in these ratios of assessed to actual value are of a reasonable size for the great majority of cases. The frequency distribution of these sample ratios was not normal, however, as was assumed a process of this type would produce. On the other hand, the failure of the regression analysis to identify any significant variables which would explain these variations would tend to re-enforce the assumption that the fluctuations were indeed of a random nature.To sum it up in one paragraph, aside from a few extreme cases, the assessing process appears to give estimates which are more consistent than would be expected under the assumption that any errors would be of a random nature, but the regression analysis was unable to isolate any particular socioeconomic characteristics which would explain the variation which was present.Financial support for this research project was furnished by the University of Tulsa.