Quantifying uncertainty of the reference sampling procedure used at Dornach under different soil conditions

The reference sampling procedure, used in the CEEM soil project on a single test area at Dornach, had been applied under different soil conditions in a sampling proficiency test and in the Swiss national soil-monitoring network related to pollution (NABO). Methods of analysis of variance (ANOVA) were used to quantify sampling and analytical uncertainty. The soil sampling procedure and the chemical analysis were considered as two parts of the same measurement process and the so-called 'top-down' approach was used to quantify their combined contribution to the uncertainty. By this approach a systematic error of one sampler or of one laboratory becomes a random error when assessed as part of a multi-sampler or multi-laboratory comparison.     

Quantitative evaluation of the CEEM soil sampling intercomparison

The aim of the CEEM soil project was to compare and to test the soil sampling and sample preparation guidelines used in the member states of the European Union and Switzerland for investigations of background and large-scale contamination of soils, soil monitoring and environmental risk assessments. The results of the comparative evaluation of the sampling guidelines demonstrated that, in soil contamination studies carried out with different sampling strategies and methods, comparable results can hardly be expected. Therefore, a reference database (RDB) was established by the organisers, which acted as a basis for the quantitative comparison of the participants' results. The detected deviations were related to the methodological details of the individual strategies. The comparative evaluation concept consisted of three steps: The first step was a comparison of the participants' samples (which were both centrally and individually analysed) between each other, as well as with the reference data base (RDB) and some given soil quality standards on the level of concentrations present. The comparison was made using the example of the metals cadmium, copper, lead and zinc. As a second step, the absolute and relative deviations between the reference database and the participants' results (both centrally analysed under repeatability conditions) were calculated. The comparability of the samples with the RDB was categorised on four levels. Methods of exploratory statistical analysis were applied to estimate the differential method bias among the participants. The levels of error caused by sampling and sample preparation were compared with those caused by the analytical procedures. As a third step, the methodological profiles of the participants were compiled to concisely describe the different procedures used. They were related to the results to find out the main factors leading to their incomparability. The outcome of this evaluation process was a list of strategies and methods, which are problematic with respect to comparability, and should be standardised and/or specified in order to arrive at representative and comparable results in soil contamination studies throughout Europe. Pre-normative recommendations for harmonising European soil sampling guidelines and standard operating procedures have been outlined in Wagner G, Desules A, Muntau H, Theocharopoulos S. Comparative Evaluation of European Methods for Sampling and Sample Preparation of Soils for Inorganic Analysis (CEEM Soil). Final Report of the Contract SMT4-CT96-2085, Sci Total Environ 2001;264:181-186. Wagner G, Desaules A, Munatu H. Theocharopolous S, Quevauvaller Ph. Suggestions for harmonising sampling and sample pre-treatment procedures and improving quality assurance in pre-analytical steps of soil contamination studies. Paper 1.7 Sci Total Environ 2001b;264:103-118.     

Objectives, concept and design of the CEEM soil project

Within the member countries of the European Union, different strategies and guidelines for the sampling and the preparation of soils are used to investigate soil contamination. As a consequence, there is reasonable doubt that the results gained by applying these different strategies and methods are comparable. In general, the relative contribution of sampling and sample preparation to the total uncertainty in soil contamination studies is a subject of speculation than of knowledge. For this purpose, the first European soil sampling inter-comparison test was organised as a project under the Standards, Measurement and Testing Programme of the European Commission. The aim of this project was to analyse and to compare the existing guidelines, the degree and the state of standardisation in this field in the European countries, and to compare their results when applied on the same test area under comparable conditions by representative sampling teams. The results of the project in general demonstrate that sampling and sample preparation errors reach about the same order of magnitude as errors caused in the chemical analysis. However, there are great differences depending on the elements investigated and their concentration ranges, as well as on pedological and land-use conditions in the test area. Consequently, sampling and sample preparation require the same attentiveness and equivalent measures for quality assurance (QA) and quality control (QC) as the chemical analysis, which has not been the case up to now. Insufficient comparability of the results is illustrated by the fact that different participants arrive at different conclusions for up to 61% of tested soil quality criteria (e.g. threshold levels). The methods and results of the project are presented in detail in the six following papers within this volume. The following 13 papers present some key studies and specific contributions of the participants, as well as synoptical papers of the invited experts in standardisation and accreditation.     

岩土工程勘察阶段的污染地基土调查

2009年修订版<岩土工程勘察规范>所做的最大修订,即为对污染地基土调查部分的修订.新修订给出了污染地基土调查的一般指导原则.污染地基土的环境调查涉及多学科的综合应用,一般岩土工程勘察单位还不具备进行污染地基土调查及对调查结果评价的能力,也不具备进行修复治理方案设计和实施的能力.本文结合实际污染地基土的调查、评价及治理...     

European soil sampling guidelines for soil pollution studies

The soil sampling guidelines used in European countries (ESSG), as kindly provided by the national institutions which participated in the project, have been recorded, studied, evaluated and presented in this paper. The aim has been to ascertain what soil sampling guidelines exist in Europe; to detect similarities and differences (comparable results), advantages and deficiencies; to identify incompatible strategies and evaluate how methodologies might affect data quality; to investigate sources of deviations or uncertainties; to improve comparability and representativeness of soil sampling; to investigate the need for harmonised sampling guidelines; and to develop suggestions for standard operating procedures (SOP). Soil sampling guidelines throughout Europe differ as to whether they are applied by law, or used throughout the country. In some countries these are ISO/DIS related or based (ISO 10381-1, 1995; ISO 10381-2, 1995), or are produced by a scientific society or a standardisation body. As far as sampling strategy is concerned, not all sampling guidelines clearly describe the sampling scale, the specifications for contamination risk precautions, the sampling plan and protocol structure and the pre-analysis treatment of the soil samples. The purpose for sampling, in descending order of frequency, is soil pollution, soil fertilisation, general soil monitoring, background risk assessment, or else it is not specified. The majority of countries do not sample the top organic matter separately. Sampling depth is either related to the morphogenetic horizon or to ad hoc sampling depth, which is not specified in all cases. They suggest mass- and volume-related soil sampling, while the sampling pattern is not presented in all national guidelines. The criteria for area, site, unit, sub-unit, and point selection are mainly based on pedology and land use, following the history and pre-screening information or geology, or is site related. Some guidelines suggest the division of sampling units into sub-units. The sampling pattern is mainly grid sampling, grid and random sampling, or not mentioned. Sampling density inside the sampling unit either varies greatly or it is not mentioned, while the size of the sampling unit varies widely. Most guidelines require the collection of composite instead of simple samples, while some prefer sampling soil profiles. In the European SSG many technical details and steps are either not defined or vary, while in the pre-analysis treatment quality assurance (QA) and quality control (QC) approaches are used either both in the lab and in the field, or only in the field, or are not mentioned. The common points and the points in which harmonisation could be started or achieved are discussed.     

受施工扰动影响土体力学参数的可视化分析方法

结合具体工程,对受施工扰动后土体力学参数分析中应用科学计算可视化分析的方法进行研究,结合体视化的算法思想,建立了受工程施工扰动土体力学参数变化的可视化分析研究方法,提出采用直接体视的算法来实现受工程施工扰动土力学参数可视化表示的解决方案。建立了用于受基坑工程施工扰动土体力学参数可视化分析的体数据V,体数据中包含了基坑外部土体的土力学参数和位移场的三维信息。按照不同的施工阶段,建立不同时间序列的系列体数据集,利用这些体数据集,可直接可视地分析施工每一工况下的坑外土体内各种土力学参数的变化和土体位移的变化。     

不同试验条件下吹填软土不排水抗剪强度对比分析

饱和软粘土不排水强度在实际工程中应用很多,不同试验方法测得的不排水强度不同。本文基于无侧限抗压强度试验和微型十字板剪切试验,对天津滨海吹填软土从取样深度变化、初始各向异性、不同加荷速率三方面进行了对比试验。试验结果表明:两种不同试验强度随取样深度的增加而增大且呈不同程度线性关联性,吹填软土受荷后应变模式、剪破面的方向、破坏标准的不同是导致试验强度差异的主要原因;初始各向异性对两种不同试验条件下的强度值有不同的规律影响,无侧限抗压强度试验强度在竖直制样方向最大,水平方向次之,斜方向最小,微型十字板剪切试验强度在水平制样方向最大,斜方向次之,竖直方向最小;加荷速率对两种不同试验条件下的强度值有相同的规律影响,两种试验强度都随着加荷速率的增大而增加。利用统计回归原理,拟合得到了原状吹填软土在两种室内试验条件下强度之间的关联表达式,便于实际工程参考。     

DX桩抗拔位移的弹性理论解析解

通过将反映桩基荷载传递机理的“套叠”式桩周土变形模式与弹性理论相结合,推导了桩身带有承力盘DX抗拔桩的荷载-位移关系的解析解。该解析解可反映桩的变形以及桩周土模量随深度变化等因素的影响,且计算较为简便。通过有限元数值模拟对计算模式可能引起的误差进行分析并以DX抗拔桩现场试验结果进行了验证,表明给出的解析解可较好地反映DX抗拔桩在工作状态下的荷载-位移关系,可为DX抗拔桩的工程设计提供参考。     

Comparative evaluation of European methods for sampling and sample preparation of soils--the Portuguese contribution

The main purpose of this work was to prepare a Portuguese sampling strategy, according to the existing Portuguese recommendations, for the soil sampling exercise at Dornach in the framework of the CEEM soil project of the SMT Programme of the EU. Within this project, the results obtained from the Dornach study were compared with the results obtained by other European participants and also with the reference sampling. The objective of this comparison was to validate the method used and to evaluate possible factors of uncertainty that may arise from the application of our national guideline as well as possible advantages. Another objective, also important, was to provide information regarding the need for a harmonised procedure within the European Union related to soil sampling and sample preparation of soils. The results obtained were consistent with the results obtained by other participants, however, in the Portuguese recommendations there is a general lack of specific information that may complicate its application to polluted scenarios. In fact, those guidelines are valuable to detect the average contamination of the soil, but they are not useful to identify hot spots or the edge influence in a contaminated land. As a conclusion, the results obtained by the CEEM soil project helped to evaluate the Portuguese sampling plan. This may provide a basis for further standardisation of soil sampling for specific purposes, e.g. contaminated land, and to establish a technical support for criteria used in the accreditation of laboratories for soil sampling.     

不同厚度与加载条件下的软基固结变形特性变化规律分析

利用海相沉积软土地基处理原位测试数据,按回归分析法研究了不同软基厚度与不同加载条件下软基的固结变形特性变化规律并进行实证。分析表明:软土层厚度与沉降之间可用线性函数拟合,软土层厚度与单位填土高度沉降之间可用对数曲线加以拟合;地质历史、软土层厚度及填土高度类似的区域,填土高度与沉降之间可用线性函数拟合,填土高度与单位软土厚度沉降之间呈现一定的相关性,且呈带宽延伸。将研究结果运用于类似工程进行实证,该成果具有较好的规律性,可以为滨海地区古海塘等的软基加固工程提供指导和借鉴。     

Description of the test area and reference sampling at Dornach

The selected test area for the comparative evaluation of European methods on sampling and sample preparation of soils (CEEM Soil) at Dornach near Basel (Switzerland) is located at approximately 400 m a.S.l. on the north-west rolling footslope of the Jura mountain chain that has a temperate climate. The area is known to be airborne polluted by emissions of a non-ferrous metal recycling plant. The geology is dominated by Jurassic limestone and (decarbonated) loess loam. The land use is deciduous forest (beech, oak) in the upper part and traditional cherry orchards with permanent grassland which have mostly been converted into arable land. The detailed soil survey distinguishes four different soil mapping units in the test area of 0.61 ha. The reference sampling was performed in a 190-m-long and 20-40 m large transect area following four devices: (1) composite samples (0-10 cm and 0-20 cm), each from 25 stratified single samples of 61 squares of 10 x 10 m; (2) hypotheses and soil horizon-based composite samples at nine locations; (3) horizon-related samples from the four described soil profiles representing the mapping units; and (4) three soil cores with 5-cm interval samples taken in the major land use units. Altogether 301 reference soil samples were taken.     

A flexible methodology for the characterisation of soils: a case study of the heavy metal status of a site at Dornach

The sampling scheme devised to study the site at Dornach was successful in identifying most of the features and element distributions in the site using only 15 composite samples. The scheme was based on dividing the area into six individual sampling units each of which represented a different combination of land use and soil type. The three-dimensional information was obtained by taking samples at different depths, either on a fixed depth basis for cultivated soils or according to soil horizons for undisturbed soils. In each sampling unit the composite samples were bulked from 12 individual samples. The sampling point for each individual sample was chosen according to a stratified random plan. Key features of the scheme were the flexibility which required the use of experienced personnel and the fact that the sole task of the sampling exercise was to characterise the site with no preconceptions of possible outcomes. The results showed that the high concentrations of Cd in the soil probably resulted from the high concentrations of Cd in the underlying limestone and not primarily from atmospheric inputs. Higher levels of copper were found in soils close to fruit trees probably as a result of using sprays on the trees. The concentrations of Pb and Zn were relatively uniform throughout the site although there was some evidence of increased Zn concentrations with depth analogous to the Cd distributions. The fact that these findings were in agreement with the known characteristics of the site indicates the successful application of the chosen methodology in this study.     

软土地区大型干坞边坡变形规律离心模型试验及实测研究

对上海外环隧道干坞边坡的开挖方法及变形规律等进行了离心模型试验研究 ,并对边坡变形监测数据进行了整理和分析 ,本文研究可对以后类似的工程提供借鉴和指导。     

潮间带原位剪切波速特性探讨及应用分析

探讨适用于近海及潮间带场区的剪切波速原位测试方法,针对黄海小洋口潮间带,进行剪切波速的原位测试,分析剪切波速的变化规律及其与土体参数的统计关系,并建立复合关系进行剪切波速预测分析,同时基于剪切波速测试成果进行应用分析。研究结果如下：通过经适性对比,近海及潮间带剪切波速测试采用单孔悬挂式方法较为适宜;剪切波速与测点深度呈相关性较好幂函数关系,按土层的统计关系分析,幂函数及其误差包络线基本反映了规律性;与土体物理力学参数的统计关系呈相关性较好幂函数或线性关系;基于测试资料,建立剪切波速 、孔隙比e、密度 及有效自重应力 的复合关系,通过计算对比分析,按此方法可以取得良好的剪切波速预测结果,亦可进行相关指标的预测分析;通过原位测试资料,进行场地土类划分对比、动参数规律性分析及地震液化判定分析,可为工程勘测、设计人员提供参考。     

倒塌结构的检测鉴定方法研究及实例分析

倒塌结构的检测鉴定具有现场情况复杂、关键性取样困难和试样有限、结构变形和损伤的时序性和分类不易确定等特点,常规的结构检测鉴定方法难以有效解决倒塌结构检测鉴定中所遇到的问题。以故障树分析理论为基础,针对倒塌结构检测鉴定工程的特点,建立了倒塌结构检测鉴定故障树模型,提出和制定了倒塌结构的检测鉴定方法和流程。以某倒塌结构的检测鉴定为例,对所提出的检测鉴定方法和流程进行了分析和应用,以期为倒塌结构的检测鉴定提供方法论和实践意义上的参考。     

A study of the factors affecting construction durations in Hong Kong

This is the second phase of an investigation into the significant factors influencing construction duration of projects in Hong Kong. The results of the first phase led to the conclusion that larger samples were justified to investigate further the discerned relationships. Expanded samples were obtained in this second phase by adding some reported data from Hong Kong projects to the original surveyed sample. The second phase of this study also further investigates the relationships between different project characteristic variables such as the construction duration, construction cost, total gross floor area and the number of storeys in the case of buildings. Moreover, a case study on plant utilization level and site labour productivity was carried out on a building site to explore the ‘micro-factors’ that affect construction durations. The findings are of importance to all construction industry participants as the derived models help to estimate the construction duration of a project on the basis of significant macro project parameters. Additionally, the results of the case study indicate the contribution of significantly variable site productivity levels to overall construction duration and suggest an agenda for future investigations. A third phase of this study is planned incorporating more detailed data collection and analysis of significant factors, as well as international comparisons where possible.     

堆载预压法在软弱地基处理中的应用

结合堆载预压法在广东科学中心软土地基处理工程中的应用实践,重点对其加固机理、方案设计及现场施工方法进行了探讨,工程实践表明,该法处理软土地基效果明显,可供类似工程参考。     

大型数控拉拔试验系统的研制及应用

跟踪国内外研发现状,结合交通部西部膨胀土项目的开展,研制了CS-LB01大型数控土工合成材料拉拔试验系统。该系统具有试件尺寸大、可采用恒力或恒速两种控制方式实现土工合成材料在不同填料中的拉拔试验、较真实模拟实际工况的特点。加载方式也因上下箱体顶(底)面设置气囊并辅以稳压伺服控制系统、设法消除填土受上下盒侧壁的摩阻影响而更加科学合理。此外,采用高精度拉力和位移传感器、自行开发数据采集分析系统并配套填料压实和起吊辅助设备,使整个系统的人工智能化水平大大提高。试验表明,该系统能较好模拟土工格栅在膨胀土中的工作状态,准确提供筋土界面间的受力、变形及变化规律,从而方便试验参数的采集及对土中加筋作用机理的研究。     

唐钢超薄带钢生产线技术改造工程勘察实例

通过对唐钢超薄带钢生产线技术改造工程勘察场地采用多种勘察方法与测试手段及现场土工试验,准确掌握了勘察场地的工程地质条件,合理确定岩土技术参数并论证岩溶和塌陷土洞的处理方案和地基基础方案,产生了良好的经济效益,对类似勘察场地的岩土工程勘察具有一定的借鉴意义。     

Temporal changes in soil properties at an upland Scottish site between 1956 and 1997

The aim of this study was to examine the frequency with which soil samples require to be taken in order to determine significant temporal changes in soil properties. The examination was carried out using data from Glensaugh Research Station in north-east Scotland where podzolic soils were sampled in 1956, 1977 and 1997, and by re-analysis of archived material. Significant differences in chemistry due to storage were detected, particularly decreases in pH of air-dried organic soils. In these cases original data were used for statistical analysis to establish changes between 1956 and 1997. Temporal changes were found for exchangeable Ca and Mg which generally decreased with time throughout the soil profile, whereas exchangeable H increased. Derived data, such as percent base saturation, declined dramatically due to decreases in exchangeable base cations. Similar podzolic soils were sampled at an adjacent Environmental Change Network (ECN) site in 1993. Application of statistical techniques to the ECN soil chemistry data allowed an estimation of the detectable change between any two years. These data along with the rates of temporal change from 1956 to 1997 allowed the calculation of the number of years required for measurable changes to be achieved. These changes and sampling intervals vary among different horizons and chemistries. Although they are site-specific, they do confirm that the current ECN protocols of a 5-year and 20-year sampling would be appropriate in order to detect changes in soil properties over time at this site.