砂卵石地层暗挖大断面隧道管棚超前支护施工技术

在砂卵石地层中管棚钻进施工难度大,精度控制困难。结合北京地铁10号线二期工程前泥洼站至西局站区间隧道砂卵石地层大管棚施工案例,对一种新的大管棚施工技术进行了介绍和评价,并提出了以后改进的方向。     

砂卵石地层暗挖地铁渡线隧道超前支护施工技术

针对大断面砂卵石暗挖施工的超前支护技术难题,分别从超前支护方式、成孔机具及工艺、注浆材料三方面介绍了具体的施工措施,即:粒径小于20cm砂卵石地层选择小导管注浆支护方式,大于20cm砂卵石地层选择大管棚注浆支护方式;使用同心跟管潜孔锤进行成孔施工;注浆材料选用改型水玻璃或水泥-水玻璃双浆液。经实践已验证了其可行性。     

大粒径卵石地层洞桩施工技术

在大粒径卵石地层进行成桩施工较困难,而在空间受限的导洞内施工难度更大。北京某地铁车站暗挖施工中,分析大粒径卵石地层洞桩难点,采取开孔前加固导坑、改进成孔设备和造浆材料、改良特殊地层等4项措施,解决了大粒径卵石地层洞桩施工易塌孔、效率低、混凝土浇筑量超大的技术难题。     

砂卵石地层旋挖桩施工常见问题分析及质量控制

砂卵石地层是一种典型的力学不稳定地层,其结构松散、无胶结、卵石粒径大小不等,具有土体内摩擦角大、塑流性差、含水量高且渗透系数大、稳定性差的特点。结合地铁某车站旋挖围护桩施工特点及现场工程、水文地质情况,总结了砂卵石地层中旋挖桩施工的质量控制措施及经常发生的卡钻、塌孔、漏浆、埋钻等问题的处理方法,对类似地层施工具有参考价值。     

砂卵石地层深孔注浆角度控制技术

暗挖法是目前城市轨道交通建设中经常采用的施工方法之一。暗挖施工过程中,不可避免地会遇到地质条件差的地层,此时确保施工安全就显得极为重要。笔者结合北京地铁昌平线二期08标段的施工过程,对砂卵石地层深孔注浆角度控制技术进行了研究,得出了以下结论:在砂卵石地层进行暗挖施工时,对地层进行深孔注浆加固可有效保证施工人员以及周围建筑物、地面的安全;控制注浆角度是保证注浆质量的重要措施。注浆角度控制技术在该工程中的应用效果较好,为类似的砂卵石地层暗挖施工提供了有益的经验。     

浅埋暗挖电力隧道穿越砂卵石地层时地上建筑物沉降控制研究

浅埋暗挖电力隧道施工容易引起地层结构变形,控制地面建筑物(构筑物)及相关管线的沉降,特别是不均匀沉降等方面仍是浅埋暗挖电力隧道施工的重点.针对砂卵石地层自稳能力差,施工过程中易出现局部坍塌的特点,宜采用管超前、短台阶、短进尺,环形开挖留核心土,及时施作初期支护,勤量测及时反馈信息等措施,来控制电力隧道围岩的变形,防止围岩坍塌,并通过压力注浆方式对地层进行预加固和超前支护,使拱部砂卵石层得到有效固结,形成注浆固结体,依托"岳各庄220 kV输变电(电力沟)工程(第五标段)",提出砂卵石地层浅埋暗挖隧道下穿施工时地层加固方案和开挖施工方法.     

砂卵石地层浅埋暗挖地铁隧道施工关键技术

为了完成北京地铁4号线12标段的施工任务，确定砂卵石地层浅埋暗挖隧道施工工艺，利用现场试验、理论分析、数值模拟、工程类比和试验室试验等多种手段，对城市地铁隧道施工关键技术进行了研究。成功开发并实施了砂卵石地层浅埋暗挖法施工工艺，实现了砂卵石地层快速施工，在机械化程度较低的条件下，月进度达到60-70m。     

常见异常无水砂卵石地层中暗挖隧道施工关键技术

北京地铁6号线西延工程无水砂卵石地层暗挖隧道施工中,拱顶及拱腰部经常出现大范围的卵石堆积区、砂层、砂卵石与黏土层混合、大直径漂石等地质突变情况,如现场未及时处理或处理效果不佳会导致开挖面小面积塌方、地面沉降过大等影响开挖安全的施工风险。结合开挖试验成果,以不扰动、少扰动土层为原则,通过采取适合地层的超前加固措施、先通过后处理、有序的塌方处理、及时回填注浆等措施,保证了开挖面的稳定,为类似工况下的施工积累了经验,供同行探讨。     

超前长小导管加固技术在砂卵石地层隧道施工中的应用

以北京地铁昌平线二期工程区间隧道矿山法施工为背景,对砂卵石地层条件下暗挖隧道超前加固施工方法进行研究。结合工程特点改进了原超前小导管加固技术,并通过现场试验验证了超前长小导管加固技术在砂卵石地层隧道施工中应用的可行性,得出了长小导管对于松散地层超前加固、塌方处理及断面变化处超前加固效果明显的结论,相关经验可为今后类似工程提供参考。     

中关村地下通道暗挖段超前支护施工技术

以北京地铁4号线中关村站与中关村西区地下通道工程暗挖段施工为例,介绍了复杂地质条件下暗挖段超前支护施工技术。该工程通过采取大管棚结合小导管注浆超前支护加固地层,并与初期支护形成棚架结构体系,共同承受管棚上部荷载,从而有效地保障了复杂地质条件下暗挖段的施工质量。     

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.