城市区域地下水非点源污染监测系统

阐述了在城市区域设立地下水非点源污染监测系统的重要性及作用,简单介绍了国外城市区域地下水水质监测系统的布置及成果,并提出了建立该系统的方法．     

Impacts of Sewers on Groundwater Quality

This paper summarizes the findings of a recent research project on groundwater contamination from leaking sewers, which was completed for the Construction Industry Research and Information Association. Fifty-four incidents were identified in England and Wales from a combined questionnaire survey and literature review. In addition to recorded incidents, the poor quality of many urban groundwaters suggests some effects from leaking sewers. Age is considered to be the most significant characteristic governing leakage from sewers; ground conditions (predominantly aquifer vulnerability) and usage (private versus public ownership) are also important factors relating to the likelihood of groundwater pollution from leaking sewers. Recommended strategies for reducing groundwater contamination include (a) modification of existing criteria for the service performance grading of existing sewers, (b) improved construction of new sewers in appropriate areas, (c) increased groundwater monitoring, and (d) risk assessments for new groundwater sources.     

深基坑坑底地基的回弹应力与回弹变形

某长条形地铁车站深基坑,基坑开挖深度15m,通过设置数个分层回弹磁环,测得回弹变形沿坑底深度方向的分布规律;通过固结回弹试验建立回弹模量与卸荷比关系,得到回弹模量沿坑底深度方向的分布规律;结合以上两种成果,并考虑坑底土承受侧向净土压力的伸长作用,得到回弹应力沿深度方向的分布规律:作用在坑底的反向荷载相当于挖去土的自重,因受坑底土有效自重应力的抵消作用,回弹应力沿深度方向呈线性衰减,坑底土的"残余应力"可以认为就是坑底回弹影响范围内的有效自重应力。用上述确定回弹应力的方法计算另一个新近案例的回弹变形,与实测结果比较接近。     

城市地下水资源评价中应特别注意的若干问题探讨

基于深圳某中心区核心地块地下水资源评价的成果分析 ,探讨了影响地下水储量及长期抽取地下水对环境影响的若干因素 ,强调了抽水试验井的成井工艺和洗井工艺及长期沉降观测在地下水资源评价中的重要性 ,提出了在水位降深不变的情况下 ,抽水井的涌水量随时间有缓慢减少趋势的观点以供探讨。     

回弹法和超声回弹综合法检测混凝土强度在工程建设中的应用

总结和分析检测混凝土强度常用的四种方法,并通过试块抗压强度检测、回弹法、超声回弹综合法的实际检测结果进行对比分析,给工程质量监督工作的现场混凝土强度检测提出一些参考意见。     

关于降水引起地面沉降问题的探讨

从理论上分析了降水引起地面沉降的原因及土层变形机理,根据计算土层压缩变形的公式,寻求了一种较为简易准确的方法对降水区土层压缩变形进行计算,将之应用于工程实践取得良好效果,为今后工程降水对周边环境的影响评价提供了方便。     

Evaluating Natural Attenuation of Groundwater Pollution from a Coal-Carbonisation Plant: Developing a Local-Scale Model using MODFLOW, MODTMR and MT3D

The effluent from a former coal-carbonisation plant in Nottinghamshire has contaminated the underlying aquifer with ammonium and organic compounds. In terms of flow and contamination, the site has experienced a complex history. MODFLOW has been used to unravel the past flow directions and to provide a basis for solute transport and biodegradation modelling. The modelling has shown that a fine grid is required to represent local flows to prevent incorrect site interpretations. A telescopic mesh technique was essential for this study to enable the site features to be adequately represented while including the regional hydrogeological influences. The influence of grid size to numerical dispersion was investigated for the MT3D computer program. The 'method of characteristics'and 'hybrid method of characteristics'modules of MT3D were found to be relatively free from numerical dispersion for all the grid sizes investigated. However, the 'modified method of characteristics'suffered extensively, and a linear relationship between grid size and numerical dispersion was demonstrated for this complex model.     

Mechanisms of Groundwater Pollution by Pesticides

An increasing number of pesticide compounds are being detected in groundwater supplies worldwide. There has, nevertheless, been little research into the mechanisms by which such pollution occurs and the routes via which pesticides move from the land surface into aquifers. In view of the potential time-lag in the response of groundwater systems to pollution inputs, such knowledge is essential if the current situation is to be appraised adequately and if any necessary controls on pesticide use are to be introduced.
From basic data on the physicochemical properties of pesticide compounds and on groundwater flow and pollutant transport in the principal British aquifers, some useful observations can be made about the relative significance of different mechanisms of potential groundwater pollution. These mechanisms and their implications for field research on pesticide pollution of groundwater are discussed. This problem is compared and contrasted to that of nitrate pollution from agricultural land-use practices.     

石家庄市地下水氮污染检测分析

石家庄市地下水的污染问题制约着该地区的经济发展,而地下水的氮污染和硬度升高是石家庄市地下水环境污染的主要问题。氮在地下水中的主要存在形式是NH3、NO2-和NO3-。根据数据采集与实验分析,得出市区的氮污染现状及污染趋势,为该地区地下水保护提供了依据。     

Groundwater Pollution in Spain: General Aspects

In spite of many aquifers still being in good condition, groundwater pollution is becoming a serious problem in some areas of continental and insular Spain, although it is not always recognized. Irrigated agriculture is an important source of pollutants, but industrial, mining and urban-related problems also exist. These go in parallel with serious salinity problems of diverse origin. The degree of knowledge with regard to these problems is still poor, and in many instances low priority is given to studies, prevention, control and remedial action. Water quantity aspects still receive most of the attention and economic resources. A new Water Act includes provisions for dealing with groundwater quality and pollution; they seem adequate to cope with existing problems, but their effectiveness, feasibility and willingness to be applied is still uncertain. The success not only depends on scientific and technical issues, but mainly in achieving an administration and management structure capable of coping with real problems and able to obtain the trust and cooperation of water users.     

Land-Surface Zoning for Groundwater Protection

A procedure for land-surface zoning, related to the protection of groundwater against both point and diffuse pollution, is described. The procedure is based upon two independent elements:
(i) Division of the entire land surface on the basis of the aquifer pollution vulnerability, which relates to protection of groundwater resources; and
(ii) A series of special protection areas for individual sources, in which various potentially polluting activities are either prohibited or strictly controlled.
The procedure is hydrogeologically based, but not so complex as to be unworkable in practice. For resource protection three classes of formation type are defined, with a further subdivision on the basis of depth to saturated aquifer. In the case of diffuse pollution, it will also be necessary to consider the nature of the soil cover in the area where the polluting activity occurs. For source protection, up to four special protection areas are specified, and the criteria used to define them are discussed.     

三氯乙烯污染地下水和土壤的修复

三氯乙烯(TCE)在工业生产中的大规模使用,使其成为地下水和土壤中分布最为广泛的污染物之一。为此综述了TCE污染地下水和土壤的修复方法,包括抽出处理和原位修复,其中原位修复包括原位化学氧化、原位电动修复、原位生物修复以及渗透反应格栅技术。     

热弥散对同井回灌地下水源热泵的影响

综述了多孔介质和含水层蓄能中常用的热弥散模型,把热弥散模型归结为两类：速度一次方模型和含水层滞止导热系数倍数模型。对同井回灌地下水源热泵（GWHPPRSW）引起的地下水的换热,针对这两类模型进行了数值求解。随着热弥散的加强,抽水温度降加大。含水层中某些地方,温度降随着热弥散的增加而减小,且变化幅值较大。含水层热影响范围随着热弥散的加强而加大。速度一次方模型的计算结果较含水层滞止导热系数倍数模型的计算结果的抽水温度降大,热影响范围小。     

回弹读数趋于稳定状态时的压强临界值

选取C20,C30,C40,C50共4种强度等级、尺寸均为100mm×100mm×300mm的混凝土试件,在5,10,15,20,25,30,40kN共7个压力等级下测量其回弹值,并通过比较回弹值与压力之间的关系,得出混凝土试件回弹值趋于稳定时的压强临界值约为0.25kN/cm2.将试验结果与原混凝土无损检测规程比对后发现,原无损检测规程在制定测强公式时规定的试件承受压力并不能确保回弹值的正确读取.所得结果可为混凝土无损检测规程的再版修订提供新的依据.     

地下水流与水质联合数值模拟应用研究

随着社会的不断发展,工业、农业和人类生活中的废弃物很多,特别是城市工业废水的大量排放,农药化肥的广泛应用,致使许多地区的地下水受到不同程度的污染。基于水动力弥散的水质模型,采用多单元均衡法（MEB）,利用VC++语言编写地下水流与水质数值模拟联合通用程序,实现程序可视化。结合实际算例,利用该程序对地下水流与水质的输运机理进行数值模拟研究,发现该程序人机对话良好,可操控性高;为地下水资源的合理开发、保护和利用进行数值模拟提供了依据。     

Q值回弹仪在现场混凝土强度检测中的应用研究

介绍了Q值回弹仪的原理、特点,以及多家机构采用Q值回弹仪开展的混凝土测强曲线研究试验工作。Q值理念回弹仪具有可在任意角度下弹击而不受重力影响的特点,因此无需回弹值弹击角度的修正;同时由于没有指针滑块,不受牵引指针运动的反弹摩擦力影响,测试结果的离散性小,且测强范围大,可达10~110 MPa等优点。实验表明,Q值回弹仪的回归方程检测精度较目前传统的R值回弹仪高。Q值回弹仪是未来回弹仪技术发展的新方向,极可能是普通R值回弹仪的替代产品。     

Practical Aspects of Yield Investigations of Groundwater Sources

Lee Valley Water plc has, in a joint study with the University of Birmingham, been reassessing the reliable yields of its existing chalk sources in order to make maximum use of the available groundwater resources. An approach to yield assessment was developed which took into account the hydrogeology and flow processes in the vicinity of pumping stations, and within the contributing area. The yield of many sources was found to be very dependent on regional water level conditions. Initial estimates of potential yields were made but future monitoring should aim to clarify the interrelationship between source output and aquifer state.     

回弹法检测烧结砖强度等级探讨

根据砌体工程实际需要,探讨了烧结砖回弹检测法中的相关技术问题,指出了现有标准的不足;通过工程实例说明了烧结砖回弹检测工作中的具体问题,其工程经验可供相关工程技术人员参考。     

率定试验在回弹法检测中的重要性

回弹法检测混凝土的抗压强度,是建筑工程检测领域中应用最为广泛的检测方法之一。为确保回弹仪的测试精度,开展检测前的率定试验是行之有效的手段。本文从回弹仪的基本工作原理出发,对各个时期《回弹法检测混凝土抗压强度技术规程》中对率定试验的规定进行了比较分析,突出了率定试验在回弹法检测中的重要性。通过某重点工程案例的经验教训,再次向广大检测工作者及建设人员强调率定试验的重要意义。最后,从仪器计量层面说明率定试验和检定试验的区别,不能简单用"率定"代替"检定"。