砂质土壤组分检测能力验证结果分析

对中国实验室国家认可委员会（CNAL）编号为CNAL T0242的砂质土壤中Cu、Pb、Zn、Mo、V五组分测试结果进行统计,采用稳健统计法,根据z比分数评判各实验室的测试结果。通过对CNAL T0242能力验证结果分析,客观反映参加实验室的测试能力和测试水平。     

高温下岩石损伤本构模型及其验证

为完善高温条件下的岩石损伤本构模型及参数确定方法,基于有效应力理论,引入Weibull分布函数,在微元体强度服从Hoek-brown准则的条件下,考虑残存强度影响,对损伤变量修正,引入损伤修正系数,建立了能够反映高温作用下的岩石损伤特征统计本构模型。考虑岩石损伤过程中的损伤阈值因素,对本构模型采用分段函数的形式。通过试验,获取常规力学参数,依据本构模型参数求解过程,确定本构模型参数值,并拟合模型参数值与温度之间的关系。对模型理论曲线进行验证。结果表明：提出的高温岩石统计损伤本构模型理论曲线与试验曲线具有较好地相似性,更加贴近试验曲线,体现了本构模型的合理性。同时模型理论曲线与岩石三轴试验曲线具有较高的吻合度,说明本构模型能够反映出岩石的全应力− 应变曲线特征,能够体现出模型的适用性。模型为岩石强度的估算和岩石热损伤软化问题提供了参考。     

古树包滑坡滑带土蠕变经验模型

针对清江古树包滑坡滑带土的室内蠕变试验资料,结合经验模型理论,以双曲线函数描述蠕变应力-应变关系,并引入Morgan Mercer Florin函数,用来描述应变-时间关系,建立了一种新的蠕变经验模型。采用/ -关系曲线和遗传算法求解出了该模型的所有参数。经过计算,所建经验模型的计算结果与实际实验数据的相关系数在0.96以上,说明所建经验模型能有效地反映古树包滑坡滑带土的蠕变特性。     

吹填软土经验流变模型研究

传统的本构模型多是在重塑土或饱和砂土的基础上建立起来,考虑结构性影响较少。自然界中土体大多具有结构性,这样就使得按传统方法计算的结果与工程实际有一定的差别。基于此,本文以Mesri模型为基础,将结构损伤变量引入模型中,建立了考虑结构性影响的流变模型。通过对天津滨海新区吹填场地经过真空预压处理的结构性吹填软土进行三轴流变试验,分析比较计算结果表明,本文建立的模型能够较好地反映结构性软土的应力应变随时间的变化关系。     

实际滑坡是滑坡危险性评价结果合理性检验最好的标准

王涛等基于简化Newmark位移模型的区域地震滑坡危险性快速评估以汶川MS8.0级地震为例一文的地震滑坡危险性快速评价结果与2008年汶川地震触发实际滑坡空间分布的相关性较低。本文试图通过对该文中基础数据、分析处理过程、研究结果的分析与讨论,找出这种相关性较低的原因。结果表明值得针对王涛等文章中的Arias烈度分布数据的准确性、工程地质岩组的划分情况、汶川地震滑坡危险性评价结果的客观性共三个方面开展更深入的分析与研究。本文对探索与发掘更客观的地震滑坡危险性评价模型起到了积极的作用。     

泰斯模型的统计分析求解

本文利用统计分析来求解水文地质参数,原理简单,解是唯一的。其基本思想是利用非稳定流抽水试验获得的s-t系列资料,以泰斯公式为参考模型,建立试验系列的非线性统计模型,求解导水系数T和贮水系数μ 。统计模型既可利用目前先进的软件辅助求解,亦可利用一台可编程计算器完成计算。本文借助一个实例,应用MATLAB语言的统计分析工具的多元回归分析模块进行求解,获得了理想的结果。     

混凝土面板堆石坝蠕变沉降经验模型及其应用

根据岩土材料Merchant、Bergers和Butterfield蠕变模型的基本形式,建立3种预测混凝土面板堆石坝蠕变沉降经验模型。以蒲石河混凝土面板堆石坝为例,采用非线性有限元方法数值模拟堆石坝的顺序填筑过程。根据堆石坝沉降现场观测数据,采用回归分析方法确定3种沉降经验模型中的待定参数,确定堆石坝的蠕变沉降随时间的变化关系。工程实践应用结果表明,所提出的堆石坝蠕变沉降经验模型具有较高的拟合和预测精度,堆石坝的蠕变沉降除与时间有关之外,还与观测点的应力状态和位置以及堆石料的变形模量有关。     

用函数模型外推法预测抗拔桩极限承载力

在桩的抗拔课题中，极限抗拔承载力的确定是其重要内容。当抗拔试桩未加载至其破坏荷载时，根据已有的荷载位移数据，用函数模型外推法预测极限抗拔承载力具有理论意义和实践意义。以工程实例为基础，用Grapher4的曲线拟合功能，选用双曲线模型、指数模型和幂函数模型，成功预测出了极限抗拔承载力。通过结果比较，表明指数函数模型具有较好的预测精度。     

钨矿石和锡矿石化学成分分析能力验证结果评价和离群值原因

金属矿产的勘查、评价、开发与综合利用要求对不同矿石品位与精矿的完整系列品质进行评价检测和仲裁测试。钨矿石和锡矿石作为金属矿的重要矿种,在客观上要求相关实验室应具备不同含量品级钨矿石和锡矿石组分的检测能力。本文按照国家认证认可监督委员会(CNCA)编号为CNCA-13-A14的钨矿石和锡矿石化学成分分析能力验证计划的要求,对中国30个省市、自治区的58个实验室提供的8个元素(W、Sn、Cu、Pb、Zn、Mo、Sb、Bi)的测定结果进行能力验证分析,采用稳健统计法,根据Z比分数判定参加实验室的检测能力。根据Z比分数≤2为满意结果的判定标准,51个实验室全部结果的Z比分数≤2,总体结果满意率(各元素的Z比分数均≤2的实验室占总实验室的比例)为88%,出现可疑和离群结果的实验室占12%。总体上钨矿石和锡矿石中元素Sb、Pb、Zn的满意率较高(其中锡矿石的Zn测定结果全部满意),W、Bi稍差;钨矿石各元素的检测水平差异小,整体结果好于锡矿石。钨矿石和锡矿石分析能力验证结果产生离群值的原因,一方面是实验室的测试水平存在差异;另一方面是各实验室采用的检测方法分散,有化学分析方法和仪器分析方法,化学分析方法检测步骤多,仪器分析方法方便快速,逐渐成为例行检测方法,两类方法的影响因素都较多。本文提出,提高实验室的检测水平和检测能力,需要适当统一检测方法,提高方法掌握的熟练程度,避免仪器状态对分析结果的影响,确保检测结果的一致性和准确性。     

An Evaluation of Methods for Assessing the Competence of Laboratories Based on Performance in the GeoPT Proficiency Testing Scheme

The original certification protocol, published by the International Association of Geoanalysts in 2003, specified that the competence of laboratories selected as competent to contribute certification measurements should be evaluated from their performance in the GeoPT proficiency testing programme. Round 39 of the IAG GeoPT proficiency testing programme provided an opportunity to examine four methods of evaluating laboratory competence based largely on the use of proficiency testing z‐scores as performance indicators. This opportunity arose because two test materials were co‐analysed by participating laboratories in this round: a syenite, SyMP‐1, supplied by the USGS, and an established CRM, the nepheline syenite, CGL 006. The performance of laboratories was assessed in four ways; in each case, consensus values and their uncertainties as derived from selective data sets of competent laboratories were compared with results derived from the routine GeoPT data assessment, involving all submitted measurements. An overall comparison of results showed no significant statistical differences in either consensus values or uncertainties between these data sets. This conclusion was unexpected and calls into question the widely held assumption that ‘better’ consensus data would be obtained from a subset of laboratories judged to be competent on the basis of proficiency testing performance indicators.     

The GeoPT Proficiency Testing Programme as a Scheme for the Certification of Geological Reference Materials

ISO Guide 35:2017 provides, for the first time, an alternative way of characterising certified reference materials using proficiency testing. In this paper, the properties of assigned values derived from the well‐established GeoPT proficiency testing scheme are examined. This scheme, designed for laboratories that undertake the routine analysis of silicate rocks and related materials, routinely has over 100 participants contributing results. Following a detailed assessment of the metrological properties of GeoPT assigned values in relation to Guide 35 recommendations, it is demonstrated that these values may be regarded as certified values, provided a number of criteria are met. These criteria include the following: a demonstration of sufficient homogeneity of the candidate CRM; circulation, when judged to be appropriate, of an established matrix‐matched CRM for co‐analysis in that round; the robust statistical analysis of data sets using GeoPT established criteria; a decision whether assigning a value is justified (including a requirement of a minimum of fifteen valid results); and an expert group to manage the certification and the maintenance of appropriate records. In summary, the GeoPT proficiency testing scheme, subject to the arrangements summarised above, is considered to be competent for the certification of geological reference materials.     

The Long‐Term Robustness and Stability of Consensus Values as Composition Location Estimators for a Typical Geochemical Test Material in the GeoPT Proficiency Testing Programme

Re‐issuing the same test material, its true identity unknown to participants, in two rounds of the GeoPT proficiency testing programme 18 years apart has demonstrated remarkable similarity, and therefore stability, of consensus values independently estimated for over fifty measurands in each round. A comparison of the two data sets, GeoPT5 (AMH‐1) from 1999 and GeoPT41 (ORA‐1) from 2017, shows that corresponding consensus values, rigorously derived by current procedures for complete compatibility, are for the most part statistically indistinguishable when account is taken of their associated uncertainties. Inferences that may be drawn from this exceptional agreement include: (a) the consensus estimation procedure was robust and gave consistent results; (b) overall, the balance of the contributed data was unaffected by significant changes in: (i) the populations of laboratories participating, (ii) the proportions of laboratories producing results by different techniques, (iii) the manner in which systems were calibrated, or (iv) the aspirations of laboratories to attain higher quality results over time; and (c) unsurprisingly perhaps, that the test material itself had remained stable and unchanged during that time. Additionally, a statistical comparison of the original values for AMH‐1 with consensus values derived by current procedures demonstrates that they are also effectively indistinguishable.     

基于EMD的云南东川蒋家沟泥石流年输沙量多时间尺度分析

基于经验模态分解(EMD)方法,对云南东川蒋家沟泥石流1965年至2004年40年的年输沙量时间序列进行多时间尺度分析,该时间序列分解成3个本征模函数(IMF)分量和趋势项(Res)分量。分析表明：蒋家沟泥石流的年输沙量存在多尺度的周期性波动,分别是2~4 a、6~10 a和17~21 a的准周期。通过对各IMF分量和Res趋势项分析发现,自1985年之后,波动的振幅开始变大,表明蒋家沟泥石流的年输沙量变化很大。降雨对蒋家沟泥石流的年输沙量及周期性波动有一定程度的影响。人类活动改变环境的同时,也为蒋家沟泥石流提供固体物质来源,这使得蒋家沟泥石流的年输沙量周期性波动变得更加复杂。     

Comparison between Empirical Estimation by JRC-JCS Model and Direct Shear Test for Joint Shear Strength

In order to study the reliability of the empirical estimation of joint shear strength by the JRC(joint roughness coefficient)-JCS(joint compressive strength) model,natural rock joints of dif-ferent lithologic characteristics and different sizes were selected as samples,and their shear strengths under dry and saturated conditions were measured by direct shear test and compared to those esti-mated by the JRC-JCS model.Comparison results show that for natural rock joints with joint surfaces closely matched,the...     

宽级配砂土基料-滤层系统的室内模型试验研究

基料一滤层利用数码可视化跟踪技术、计算机信息实时处理技术和土体变形无标点量测技术,对宽级配基料一滤层系统进行了渗透室内模型试验。探讨了滤层准则的适用性,研究了不同滤层厚度和加压速率对管涌发生发展的影响。结果表明：传统太沙基滤层准则不适用于宽级配砂土,建议采用可移动颗粒中的d85s进行滤层准则设计;增加滤层厚度可提高系统的抗渗透破坏能力,但提高滤层厚度对提高整个系统抵抗渗透能力作用不大;水力梯度增加较快不利于系统的稳定。     

The Reliability of Assigned Values from the GeoPT Proficiency Testing Programme from an Evaluation of Data for Six Test Materials that have been Characterised as Certified Reference Materials

Assigned values derived from the GeoPT proficiency testing programme were compared with certified values for six certified reference materials that have been used as test materials in the GeoPT programme. Statistical analysis showed that there were few significant differences between these sets of data and that these differences had no significant impact on the GeoPT assessment when fitness‐for‐purpose criteria were taken into account.     

Bias in the Determination of Zr,Y and Rare Earth Element Concentrations in Selected Silicate Rocks by ICP‐MS when Using Some Routine Acid Dissolution Procedures: Evidence from the GeoPT Proficiency Testing Programme

The analytical results for the modified river sediment, SdAR‐1 circulated in Round 31 of the GeoPT proficiency testing programme, revealed unexpected discrepancies for Zr, Y and most higher atomic number rare earth elements, in determinations made by ICP‐MS using acid attack digestion methods. This investigation compares these ICP‐MS results with those obtained for SdAR‐1 by three other methods: (a) ICP‐MS using fusion/sintering for sample digestion, (b) XRF analysis and (c) INAA. The distribution of results for the elements Rb, Sr, Ce, Y, Yb and Zr is examined and compared with those of the test material for Round 25 of GeoPT, Paraná basalt, HTB‐1. A substantial proportion (though not all) of Y, Yb and Zr determinations in SdAR‐1 by ICP‐MS/acid attack was variably low (sometimes very low) compared with other methods. A detailed evaluation of the procedures used to determine these results indicated that successful determinations by ICP‐MS/acid attack could be made if digestions were made at 180 °C for 48 hr using at least 2 ml HF per 100 mg of sample. We suggest that the more benign conditions (used by many laboratories) resulted in incomplete digestion of resistant minerals, such as zircon.