钢管混凝土拱桥施工方面的研究

对钢管混凝土拱桥施工过程中的钢管拱架设方法、施工应力与变形分析、施工稳定分析、局部受力分析等方面的研究进展进行了综述.     

钢管混凝土拱桥施工控制软件的开发

钢管拱肋架设质量的好坏是钢管混凝土拱桥施工控制的关键工序,针对其施工控制的这一特点,介绍了钢管混凝土拱桥施工控制中倒退分析软件的编写思路及关键问题的具体处理方法。     

劲性骨架钢管拱肋外包混凝土施工技术

结合威坪大桥工程实例,介绍了劲性骨架钢管拱肋外包混凝土施工模板架设、混凝土浇注的方法.     

下承式钢管混凝土刚架系杆拱桥施工过程的模拟

钢管混凝土刚架系杆拱为自架设体系,拱脚与墩固结,系杆拉力抵消拱的大部分水平推力,施工过程中拱肋弦杆由钢管渐次向钢管混凝土转变,截面强度和刚度逐步形成,系杆拉力也在不断变化。文中以某跨度135 m的下承式钢管混凝土刚架系杆拱桥为例,详细模拟该钢管拱桥的施工过程,并以图表形式示出施工过程中拱脚和拱顶截面弯矩、系杆拉力等典型受力曲线。     

超大跨径钢管混凝土拱桥主拱线形控制误差分析

大跨径钢管混凝土拱桥是一种自架设体系结构,结构的刚度随施工的进行逐渐组合而成,拱肋的线形控制是实现设计成桥目标的关键。在类似采用斜拉扣挂法施工的超大跨径钢管混凝土拱桥拱肋吊装过程中,主拱线形除了受索力误差、温度误差等传统因素影响外,还有一些潜在误差也应引起重视,如自重误差、定位误差、扣塔偏位误差等。该文以合江长江一桥拱肋吊装为背景,对索力误差及上述潜在误差对主拱线形可能产生的影响进行了计算分析,以期对此类超大跨径钢管混凝土拱桥主拱线形控制起到一定的借鉴作用。     

拱桥拱肋线形的安装控制技术

桁架式钢管系杆拱桥有效地发挥了混凝土和钢材的力学特性,利用钢管的环箍作用,大大提高结构的抗压能力和抗变形能力,并且其造形美观、结构严谨、受力科学、经济合理,但其技术含量高、工艺严格、工序繁多、施工难度大。在此以湖州市二路四桥奚家庄大桥工程为例,针对桁架式钢管拱桥采用缆索吊系统安装过程中影响拱肋线形的关键因素,提出了在钢管制作和架设安装中的拱肋线形控制要点和技术。     

柳州维义大桥钢桁拱梁膺架法半悬臂架设施工

对钢桁拱梁架设方法进行了分析,结合工程实践,介绍了钢桁拱梁膺架法架设方案、总体布置、架设工况设计、临时支墩设计、临时杆件设计、主边墩墩顶布置、跨中合龙等关键技术,提出了在主跨采用膺架法半悬臂架设的施工方法,并获得了成功。     

钢管混凝土拱桥混合施工方法分析研究

基于某上承式钢管混凝土拱桥主拱架设的复杂施工条件,提出了对主拱肋拱脚段采用支架施工法,后续节段采用斜拉扣挂法的混合施工法。通过Midas/Civil有限元软件模拟分析了该混合施工方法的合理性,并与扣挂法的受力特点进行了对比分析。结果表明,两种施工方法成拱内力分布大体一致,混合施工方法成拱线形更加接近设计线形,对于施工条件允许且线形精度要求高的同类桥梁施工时适合选用此法。     

钢管混凝土拱桥施工中的计算机辅助方法

钢管混凝土拱桥因美观的外型和优良的材料性能而受青睐。由于钢管混凝土拱桥施工中拱肋的线形控制及应力状态复杂，所以是控制的重点和难点。在线性控制方面，钢管拱肋的加工及拱肋梁段的拼装是线性控制的基础和能否顺利施工的保证。为了保证钢管拱肋的线形，传统采用现场预拼的方法。现场预拼对场地条件要求高，耗时耗钱，施工对拱肋段损伤大，有时根本无法实现全跨预拼。所以，亟需一种快捷的方法对加工质量进行检验和拼装模拟；在混凝土灌注施工中，钢管拱的结构刚度随着加载施工不断变化，稍有不慎就可能引发工程事故。为了保证施工安全，提高灌注质量，必须进行应力测试与监控。本文试图通过衡南桥施工控制中利用计算机辅助线形检测及预拼装模拟和运用计算程序模拟加载分析，优化加载程序，介绍一种在钢管混凝土拱桥施工过程中的计算机辅助施工方法。     

奉节梅溪河钢管拱桥建造技术

三峡移民重点工程之一的奉节梅溪河桥，日前已成功合龙贯通。由中铁大桥工程局设计、承建的梅溪河公路大桥，全长491m，采用上承式钢管混凝土无铰拱桥桥式，一跨过河，跨距288m。 钢管拱桥具有桥式美观、大跨轻质、投资节省诸多特点。在梅溪河桥建造中，依靠科技进步优化施工工艺，创出了4个国内第一：①主跨288m的上承式钢管混凝土桁架有推力拱拱桥，为国内首创，其跨度在目前世界同类桥梁中位居第二，亚洲位居第一；②主拱架设采用跨度为500m的缆索吊机吊装和斜拉扣挂悬臂施工新工艺，为国内首创，其技术工艺达到世界建桥先进水平；③钢管拱拱脚架设采用绞接新技术，有效地解决了14段共28节钢管节段的对位难题，为国内首创；④拱座上设置国内首创的水平撑刚构穿过卸荷带，有效地防止了推力拱重量压在桥面，导致卸荷带发生裂隙而影响拱桥质量的难题。 (摘自《中国建设报》2000-11-09)     

Development and applications of trenchless technology in China

Trenchless technology has developed for almost 10 years in China since the first symposium on trenchless technology was held in Beijing (Peking) in 1996 and the China Society for Trenchless Technology-CSTT was established in 1998. Driven by the dramatically increased demand for underground pipeline installation throughout the nation, China has made significant progress in research and development in trenchless technology in the past 10 years. For example, there are more than 200 contractors engaged in trenchless construction, using more than 2000 horizontal directional drilling machines, among which approximately 700 have been introduced in the last year, and the biggest HDD rig in the world is now in China. In addition, China has made many achievements in education, research, and new products development and has accomplished many challenging projects in terms of complexity, diameter and distance in this field. There is a huge market potential for trenchless technology in mainland China.This paper presents the latest research, education, training, marketing and technical status of trenchless technology in China, and discusses the potential market, trends and factors that will influence trenchless technology in the next decade in China.     

Health assessment of artisanal gold miners in Indonesia

Small scale miners use mercury to extract gold from ore in many countries. An environmental and health assessment was performed in Indonesia in two regions, Galangan in Central Kalimantan and Talawaan in Northern Sulawesi. The environmental assessment showed severe mercury contamination of the sediments, and increased mercury levels in local fish. For the health investigation 281 volunteers were recruited and examined by a standardized questionnaire, a neurological examination and neuro-psychological tests. A medical score was used consisting of significant factors of mercury intoxication. Mercury exposed workers showed typical symptoms of mercury intoxication, such as movement disorders (ataxia, tremor, dysdiadochokinesia, etc.). Blood, urine and hair samples were taken from any participant and analyzed for mercury. The mercury concentration in the biomonitors was high, partly extreme high in the working population, increased in the population living in the same habitat and low in the control group. By a standard protocol which includes a combination of threshold values of mercury in the biomonitors and a medical sum score the diagnosis of chronic mercury intoxication was made for highly burdened workers (amalgam smelters) in 55% in Sulawesi and in 62% in Kalimantan. Less exposed mineral processors and the general population in the mining areas were also intoxicated to a high percentage.     

Urban environmental mercury in Changchun, a metropolitan city in Northeastern China: source, cycle, and fate

Mercury concentrations in each environmental compartment in Changchun City had obvious spatial and temporal trends. Particulate Hg (HgP) and total gaseous mercury (TGM) concentrations in air, total Hg (HgT) concentrations in precipitation and ratios of HgP to HgT (total Hg in air) in the atmosphere in heating season were higher than those in non-heating season, which resulted from civil heating. In contrast, reactive Hg (HgR) concentrations in precipitation were higher in non-heating season than those in heating season. TGM and SO2 in air had good agreement. HgP concentrations in the atmosphere were correlated with HgT concentrations in precipitation. Based on Hg concentrations in each environmental compartment, Hg exchange fluxes between environmental interfaces were estimated. Only 11.6% of Hg, emitted from coal combustion, deposited into land surface in urban district and the rest part participated in regional or global cycle, so urban district was the source of Hg global and regional cycle. Net fluxes of Hg into land surface and water were 34.26 kg year(-1) and 0.051 kg year(-1), respectively, which were clearly accumulated in the water and soil. Therefore considering urban local Hg cycle, each environmental compartment of urban ecosystem (water, air and soil) was the sink of Hg.     

脂肪肝患者中医体质分类及相关指标分析

目的了解脂肪肝患者中医体质分布特点及与相关指标的关系。方法采用流行病学调查的方法,对518例脂肪肝患者和227例非脂肪肝患者进行中医体质判定及相关体检指标（血生化,肝、胆B超）统计。结果脂肪肝患者各种体质分布：湿热质20.9%,气虚质18.7%,痰湿18.5%,平和质17.6%,阴虚质7.9%,阳虚质5.0%,气郁质4.4%,瘀血质3.1%,阳盛质2.5%,血虚质1.2%,肾虚质0.2%。与非脂肪肝患者比较,脂肪肝患者高血脂的人数比例显著升高（P〈0.05）;肝内胆管结石、胆囊结石、胆囊炎、胆囊息肉、胆囊切除等所占比例明显增高（P〈0.05或P〈0.01）。结论脂肪肝患者以偏质为主,且与血脂高密切相关,更容易合并肝胆结石、胆囊炎及息肉等疾病。     

Heavy metal contaminants in Red Pandora (Pagellus erythrinus) tissues from the Eastern Aegean Sea, Turkey

Heavy metal contents were investigated in different organ tissues of Red Pandora (Pagellus erythrinus) from the eastern Aegean Sea between May 1996 and July 1998. The concentrations of mercury in the muscle tissue ranged between 16 and 716, in liver 125-5451, in gonad 2.0-1858; cadmium in muscle nd-9.6, in liver 1.4-2245, in gonad nd-192; lead in muscle nd-1397, in liver 112-8311, in gonad nd-2927; zinc in muscle 1352-6693, in liver 2710-78705, in gonad 7273-168655; copper in muscle nd-383, in liver nd-21986, in gonad nd-20499 (microg/kg wet weight). The highest concentrations were generally found in the Southern Aegean Sea. All metal levels in muscle tissues are lower than the limits of European Dietary Standards and Guidelines. The metals ratios between liver and muscle indicated that the liver accumulated higher levels of metals than the muscle tissues. The bioaccumulation factor (BAFs) of metals was measured in muscle, liver and gonads. BAFs among the analysed elements showed the descending orders as Zn>Cu>Cd>Pb for muscle and gonads and Cd>Zn>Cu>Pb for liver.     

儿童嗜酸细胞性胃肠炎的临床、内镜及病理学特点

目的研究儿童嗜酸细胞性胃肠炎（EG）的临床表现、内镜下特点及组织病理学改变,以提高儿童EG的诊断水平。方法对43例EG患儿的临床资料（临床表现、内镜下特点及组织病理学改变）进行回顾性分析。结果 43例EG患儿中腹痛26例（60.47%）,呕吐19例（44.19%）,腹胀16例（37.21%）,呕血13例（30.23%）,便血7例（16.28%）,外周血嗜酸性粒细胞升高35例（81.40%）。镜下均表现为胃及十二指肠黏膜充血、水肿,伴有点、片状糜烂,单发或多发性溃疡,其中胃炎40例,胃溃疡2例,十二指肠球炎23例,十二指肠球部溃疡7例,结肠炎1例。组织病理均见嗜酸性粒细胞浸润（〉20个·HPF-1）。结论儿童EG的临床表现和内镜下表现均无特异性,胃肠黏膜组织中嗜酸粒细胞计数是诊断的关键。EG极易造成误诊,明确诊断需依靠活组织病理检查及嗜酸粒细胞计数,并结合临床特点来证实。     

岩石爆炸动力学的若干进展

 论述岩石爆炸动力学原理及其工程应用研究近年来的若干进展,主要内容包括爆炸空腔范围以及各类破坏区范围的理论确定方法,地下爆炸近区的“短波”和“弱波”理论,爆炸远区——弹性区的运动和力学参数以及地下爆炸时岩石破碎等理论研究成果。同时还介绍了实验室条件下均匀介质中爆炸效应的规律和地应力、裂隙、浅埋时等不均匀、不连续性影响因素的实验室模拟爆炸试验研究。在相关研究的基础上,给出实际岩体中的爆炸效应试验,包括近区破坏效应、远区地震效应、不可逆变形区以及地下爆炸和浅埋(抛掷和定向)爆炸中相似关系的最新成果。此外,简要介绍岩石爆炸动力学在不同领域中的工程应用,并就今后岩石爆炸动力学研究的展望阐述一点认识。     

Factors affecting bulk to total bacteria ratio in drinking water distribution systems

Bacteria in drinking water systems can grow in bulk water and as biofilms attached to pipe walls, both causing regrowth problems in the distribution system. While studies have focused on evaluating the factors influencing the bacteria in bulk water and in biofilms separately, there is a need for understanding biofilm characteristics relative to the bulk water phase. The current study evaluated the effects of chlorine and residence time on the presence of culturable bacteria in biofilms relative to that in bulk water. The results showed that when no chlorine residual was present in the system, the median ratio of bulk to total bacteria was 0.81, indicating that 81% of the bacteria were present in bulk water, whereas only 19% were present in the biofilm. As chlorine concentration increased to 0.2, 0.5, and 0.7 mg/L, the median percentage of bacteria present in bulk water decreased to 37, 28, and 31, respectively. On the other hand, as the residence times increased to 8.2, 12, 24, and 48h, the median percentage of bacteria present in bulk water increased to 7, 37, 58, and 88, respectively, in the presence of a 0.2mg/L chlorine residual. The common notion that biofilms dominate the distribution system is not true under all conditions. These findings suggest that bulk water bacteria may dominate in portions of a distribution system that have a low chlorine residual.     

Cell phones for the spirits: ancestor worship and ritual economies in vietnam and its diasporas

Religion has been thriving in the Socialist Republic of Vietnam since ??i m?i, the onset of market reforms in the late 1980s. Votive paper offerings, part of spiritual and economic well-being, play a crucial role in performing religious practices in the socialist country as well as among diasporic Vietnamese. In urban Hanoi, material objects made from paper are traded in marketplaces and later burned in the streets, in temples and pagodas, in private yards and other places on special occasions in order to be transmitted to the ancestors. In the past few years, the range of votive paper offerings produced, traded, and sent to the deceased has expanded to include new forms and references to new media. Drawing on recent debates in the role of media in religion and in particular on technologies of mediation, I focus on the use of votive paper offerings in the sociocultural context of the Vietnamese spirit world. I explore how new media and media technologies are embedded in multilayered processes of mediation in Vietnam and its diasporas. Taking religious practices of burning votive paper offerings as an ethnographic example, this essay aims to contribute to ongoing debates on popular religion and the sacred life of material goods in late socialist Vietnam, on its transnational ties, and on the entanglements between religion, media and materiality.     

胰腺实性假乳头状瘤 10 例临床分析

目的：探讨胰腺实性假乳头状瘤（SPTP）的临床特征、治疗及其预后。方法回顾性分析经手术及病理检查证实的10例 SPTP 患者的临床资料。结果10例患者术后恢复良好,均未出现胆瘘、胰瘘及糖尿病等并发症。8例患者行免疫组织化学检测,其中 NSE 阳性8例,阳性表达率为100．0％;Syn、Vim 和 PR 阳性各7例,阳性表达率均为87．5％;Ki-67部分阳性6例,阳性表达率为75．0％;CK 局灶阳性4例,阳性表达率为50．0％;CD99阳性3例,阳性表达率为37．5％;CK18局灶阳性2例,CD10阳性2例,阳性表达率均为25．0％;CD56、α-AT、α-ACT 和CgA 阳性各1例,阳性表达率均为12．5％;EMA 阴性8例,阴性表达率为100．0％。2例患者未行免疫组织化学检测。10例患者随访时间为6～72个月,均未发现肿瘤复发及转移。结论SPTP 是一种潜在低度恶性肿瘤,可能来源于胰腺胚胎多能干细胞,手术切除是首选的治疗方法。