基坑工程若干基本问题的讨论—基坑开挖与支护研讨会综述

本文概要地综述了基坑开挖与支护研讨会上各位专家的讨论发言及交流资料，介绍了与会专家们对目前基坑工程设计及施工中存在的主要问题的认识，并强调了基坑工程中经验的重要性及监测工作的必要性。     

通信基站监控系统的设计

通信基站监控系统的设计是集计算机技术、通信技术和测控技术的综合应用.该系统实现了对通信基站设备工作状况、工作环境的实时监测,提高了基站安全保障与工作的有效性,也提高了通信网络设备的现代化管理水平.对通信基站监控系统在实现过程中遇到的若干关键问题进行了较为详细的分析并给出了解决方案.     

Urinary mercury in people living near point sources of mercury emissions

As part of the European Mercury Emissions from Chlor Alkali Plants (EMECAP) project, we tested the hypothesis that contamination of ambient air with mercury around chlor alkali plants using mercury cells would increase the internal dose of mercury in people living close to the plants. Mercury in urine (U-Hg) was determined in 225 individuals living near a Swedish or an Italian chlor alkali plant, and in 256 age- and sex-matched individuals from two reference areas. Other factors possibly affecting mercury exposure were examined. Emissions and concentrations of total gaseous mercury (TGM) around the plants were measured and modeled. No increase in U-Hg could be demonstrated in the populations living close to the plants. This was the case also when the comparison was restricted to subjects with no dental amalgam and low fish consumption. The emissions of mercury to air doubled the background level, but contributed only about 2 ng/m(3) to long-term averages in the residential areas. The median U-Hg levels in subjects with dental amalgam were 1.2 microg/g creatinine (micro/gC) in Italy and 0.6 microg/gC in Sweden. In individuals without dental amalgam, the medians were 0.9 microg/gC and 0.2 microg/gC, respectively. The number of amalgam fillings, as well as chewing, fish consumption, and female sex were associated with higher U-Hg. The difference between the countries is probably due to higher fish consumption in Italy, demethylated methyl mercury (MeHg) being partly excreted in urine. Post hoc power calculations showed that if the background mercury exposure is low it may be possible to demonstrate an increase in U-Hg of as little as about 10 ng/m(3) as a contribution to ambient mercury from a point source.     

探讨城市污水在线监测系统的应用

介绍了水质、水量在线监测系统的发展、应用情况以及系统所采用的在线设备和指标。详细描述了污水厂在线监测系统的结构、数据采集、传输方式及其辅助系统，指出了系统应用中出现的问题。     

乌鞘岭隧道F4断层区段二次衬砌安全性分析

掌握二次衬砌结构受力的规律,确定隧道衬砌安全性,在F4断层主带和影响带进行了初期支护与二次衬砌间接触压力监控量测,并利用量测结果对实测荷载下二衬的安全性进行了分析,以指导隧道的设计和施工。     

基于AIC准则的回归方法在建筑物变形分析中的应用

鉴于引起建筑物变形的地质、水文、气候、附近开挖等原因的不确定性和各种因素影响度的不确定性,本文提出将基于AIC准则的回归理论应用到变形分析中,实现了多项式回归系数和幂次方的自适应处理,并实现了建筑物变形分析中变形因子和回归函数的自动确定。在MATLAB下编写了算法,并提出了优化方案。实践证明,这一理论很适合于变形分析。     

隧道初砌裂缝病害成因分析

针对公路隧道的裂缝问题,结合青莱高速公路马莱段城岭隧道初砌裂缝的监测工作,分析了隧道典型裂缝的基本特征及产生原因,得出偏压、纵向沉降差、施工工序等是隧道裂缝产生的主要原因的结论。     

南太子湖拱形连续箱梁的施工控制

拱形连续箱梁设计新颖,结构复杂,施工监控难度大。该文以武汉南太子湖大桥为例,采用有限元方法建立了全桥仿真计算模型,系统研究了拱形连续箱梁桥的线形和应力控制技术。监测结果表明,桥面标高的最大偏差为14 mm,轴线偏差为6 mm;成桥时,最大压应力为7.02 MPa,各截面混凝土下缘没有出现拉应力。实测数据表明南太子湖大桥的成桥线形和成桥后各截面应力均满足设计规范要求。     

汽车起重机起升机构液压系统的改进

本文对汽车起重机起升机构普遍存在的"二次下滑"问题进行了分析研究,并对改进后的起升机构液压系统利用功率键合图和状态空间法进行动态特性分析和理论验证.     

A multi-layer sampler for the study of detailed hydrochemical profiles in groundwater

A modular multi-layer sampler was developed and utilized for sampling undisturbed groundwater chemical profiles. Sampling at 3 cm depth intervals is based on the dialysis-cell method and has no depth limitations. The sampler may be used for water quality monitoring and research, both in existing or specially drilled screened wells