国际大坝工程研究动态——‘95马来西亚大坝工程国际学术会议简介

笔者通过对参与’９５大坝工程国际学术会议共１２６篇论文及加拿大大坝安全协会所作的“加拿大大坝安全指南”学术报告的分析和归纳，就目前国际大坝工程研究中的大坝安全规范及管理，水电工程开发与环境保护，大坝地基处理，大坝筑坝关键技术及新型筑坝材料等五个方面的动态作了简介。     

基于IGGⅢ稳健估计法在大坝沉降监测中的应用

了解大坝变形,发现大坝安全隐患是人们所关注和关心的,而大坝沉降的变形监测数据是判断大坝是否变形最直接、最重要的依据。因此,获取监测数据并进行有效深入的分析及处理,不仅是相关规范的要求,更是反映了大坝现状的重要信息。本文比较了最小二乘法和IGGⅢ稳健估计法在处理12期大坝沉降数据过程中的优劣,由结果可知,IGGⅢ稳健估计法更能克服单一状态估计算法不能抗拒粗差的缺陷,同时具备精度高、运算速度快等优点。     

Shaking table test on small‐scale retrofitted model of Sefid‐rud concrete buttress dam

Sefid‐rud concrete buttress dam with a height of 106 m was damaged during the devastating 1990 Manjil earthquake. The dam was repaired and strengthened using epoxy grouting of cracks and the installation of post‐tensioned anchors. In a previous study, nonlinear seismic response of the highest monolith with empty reservoir was investigated experimentally through model testing. A geometric‐scaled model of 1:30 was tested on a shaking table to study dynamic cracking of the model. As a result of the similarity between model and prototype cracking pattern, the model was retrofitted according to prototype retrofitting plan after the Manjil earthquake and re‐tested on shaking table to estimate the current safety of the prototype. Experimental test results showed that the post‐tensioning resulted in a significant decrease in dynamic responses in terms of crest displacement and measured strains of the retrofitted model in comparison with its corresponding responses at the first test. No cracking was observed in the retrofitted model when the base motion peak acceleration exceeded a value that was 22% higher than the one caused cracking in the first model. This can be interpreted as the efficiency of prototype post‐tensioning system in evaluating the seismic safety of Sefid‐rud dam. Copyright © 2009 John Wiley & Sons, Ltd.     

吉林抚松老松江水电站坝基和坝体应力应变分析

以岩土力学为基础的土坝设计方法,能够定性和半定量地分析坝体和地基稳定性、估算坝体和地基的沉降量,而不能全面分析地基和坝体内部应力应变状态.采用邓肯E-K模型,对水电站坝基和坝体在填筑和蓄水条件下的应力和变形进行了动态模拟计算,结果表明,坝体和心墙垂直和水平变形在竣工和蓄水期均符合规范要求,心墙在蓄水期间不会产生水力劈裂.     

Evaluation of the water quality at Tahtali dam watershed in Izmir-Turkey by means of statistical methodology

Sustaining the human ecological benefits of surface water requires carefully planned strategies for reducing the cumulative risks posed by diverse human activities. Municipal governments in Izmir City play a key role in developing solutions to surface water management and protection. Therefore, several methodologies are carried out to develop new solutions for protecting available water resources. In the present study, the major chemical loads of surface water at the Tahtal? dam reservoir were evaluated statistically by using monthly averaged values of the measured parameters. Here, the SPSS and NCSS statistical programs were applied during the statistical analyses. Analyses were carried out in two stages. In the first part of the statistical analyses, the mean, median, minimum, maximum, 25th and 75th quartiles were calculated. In second part, the data were investigated by using statistical median test, normality test, parametric and non-parametric correlation and regression analyses. These methods were performed on water quality data taken from four sample sites representing the recharge and discharge areas at the Tahtal? dam. The Median test is applied to check if medians of water quality data from four sample sites (Derebo?az?, Bulgurca, Menderes and Gölcükler) are equal or not. Commonly a non-parametric test (distribution-free test) is used to compare two independent groups of sampled data. Since there are more than two groups in independent group comparison, Kruskal–Wallis test is applied instead of Mann–Whitney U test. Finally, the main objective of using statistical analyses in third research is to estimate the types of pollution sources, the level of pollution and its environmental impacts on the Tahtal? dam reservoir by means of statistical methodology.     

Transport of suspended sediment under the dam‐break flow on an inclined plane bed of arbitrary slope

The problem of transport of suspended sediment after the break of a dam on an inclined bed is considered. To that end we use the shallow‐water approximation for arbitrary, constant slopes of the bottom, taking into consideration the effect of friction. The numerical technique and the frictional model are validated by comparison with available experimental data and asymptotic analytical solutions, with special attention to the numerical solution near the wetting front. The transport of suspended sediment down the inclined bed is obtained and discussed as a function of the slope of the bed for different values of the parameters characterizing the sediment and its transport properties. For sufficiently large times we always find the formation of roll waves near the water front, which affects the transport of sediments significantly. These strong oscillations are accurately computed with the numerical method used. The relative importance of the bed load (to the suspended load) sediment transport is also discussed as a function of the size of the sediment particles and the slope of the bed for different models on the initiation of sediment suspension from bed load. We also check the dilute sediment approach and characterize the conditions for its failure. Finally, the results of the present simplified model are intended to be used as tests of more complex numerical models. Copyright © 2007 John Wiley & Sons, Ltd.     

清江水布垭工程坝址岩体稳定性三维数值模拟研究

清江干流水布垭水电枢纽是与隔河岩、高坝洲水电枢纽并重的国家级大型水电工程 ,坝址区高边坡稳定性问题是水布垭坝址主要的工程地质问题之一。采用三维有限元数值模拟方法 ,对坝址区岩体应力场和位移进行了研究 ;探讨了岩体三维应力、应变分布与岩体变形破坏的关系 ,评价了岩体的稳定性     

Response surface and genetic method of deformation back analysis for high core rockfill dams

High core rockfill dams exhibit complex deformation mechanisms because of complicated geological conditions, many material partitions and severe weather conditions. When realistic parameters cannot be obtained through laboratory tests or engineering analogies because of effects of size or time, back analysis is necessary to predict deformation characteristics. This paper proposes a method of deformation back analysis based on the response surface method and genetic optimization theory. The parameters of the creep and Duncan–Chang models for the Pubugou gravelly soil core rockfill dam are sequentially calculated. Back analysis performed using this method efficiently yields more precise results than those obtained from laboratory-determined parameters.     

强震观测在小浪底水利枢纽大坝监测中的应用

文章结合小浪底水利枢纽的实际情况,就强震观测系统在小浪底大坝监测中的应用,从系统的设计、台站构成以及正常运行情况做了详细介绍,可为其它同类大坝的强震监测设计提供直接依据。     

A correlation for permanent earthquake-induced deformation of earth embankments

Seismic design of earth dams and embankments is mainly controlled by the permanent deformation that may be induced directly or indirectly because of the design earthquake. Simple design charts, such as those developed by Yegian et al. [Yegian, M.K., Marciano, E.A., and Ghahraman, V.G. 1991. Earthquake-induced permanent deformations: Probabilistic approach. J. Geotech. Eng., 117, 35–50.], Hynes-Griffin and Franklin [Hynes-Griffin, M.E., and Franklin, A.G. 1984. Rationalizing the Seismic Coefficient Method. Miscellaneous Paper GL-84-13, US Army Corps of Engineers Waterways Experiment Station, Vicksburg, Mississippi.], Makdisi and Seed [Makdisi, F.I., and Seed, H.B. 1978. Simplified procedure for estimating dam and embankment earthquake-induced deformations. J. Geotech. Eng., 104, 849–867.], and Sarma [Sarma, S.K. 1975. Seismic stability of earth dams and embankments. Géotechnique, 25, 743–761.], are often used to obtain a preliminary estimate of the permanent, earthquake-induced deformation of earth dams and embankments. Comparison of permanent deformations estimated from these procedures with observations from 122 published case histories on performance of earth dams and embankments during past earthquakes indicate that the estimated permanent earthquake-induced deformations were, in general, smaller than the observed deformations. However, the observed permanent deformation, D_avg, was found to relate to the ratio of yield acceleration, a_y, and the peak horizontal ground acceleration, a_max. The scatter in the observational data, upon which the D_avg–a_y/a_max relationship is based, can be partly explained by the variations in the ratio of the fundamental (elastic) period of the earth structure, T_D, and the predominant period of the earthquake ground motion, T_p, and the magnitude of the earthquake, M_W.