顺层蠕动边坡变形破坏机理及稳定性动态分析   总被引：11，自引：5，他引：11  

杨天鸿  芮勇勤  李连崇  马新民  申力 《工程地质学报》2003,11(2):155-161

本文以阜新海州露天矿边坡为例, 分析了边坡变形规律和破坏机制。在弱层流变试验的基础上, 建立了弱层流变力学模型, 通过确定加速蠕变阶段来临的极限应变量和应变速率, 建立了弱层长期强度的时间效应方程, 对于不同边坡工况进行了动态稳定性评价, 为采取抗滑措施控制蠕动边坡的变形破坏发展提供了科学依据。最后提出了一个边坡加速蠕变阶段来临的预测预报方法, 分析结果和实测资料较为一致。  相似文献   

Effects of the Herbicide Metazachlor on Phytoplankton and Periphyton Communities in Outdoor Mesocosms     

Udo Noack  Thomas Geffke  Ramani Balasubramanian  Jutta Papenbrock  Mike Braune  Dirk Scheerbaum 《洁净——土壤、空气、水》2003,31(6):482-490

The effects of the chloroacetanilide herbicide metazachlor have been investigated in outdoor artificial mesocosms. Decreasing phytoplankton densities were caused by the application, however, the communities recovered after 30 to 35 days. Periphyton growth was found to be affected not only by the herbicide application but by the presence of species with different ability to grow on artificial substrates. Zooplankton diversity was small due to low density of ingestible algae species. Oxygen saturation was found to be correlated with the dosage levels of the herbicide in the second half of the study.  相似文献   

Use of Plant Bioassays for the Detection of Genotoxins in the Aquatic Environment     

Bernhard J. Majer  Tamara Grummt  Maria Uhl  Siegfried Knasmüller 《洁净——土壤、空气、水》2005,33(1):45-55

The present article describes the use of plant bioassays for the detection of genotoxins in the aquatic environment and gives an overview of test methods, their detection spectrum for environmental mutagens and carcinogens and their limitations and pitfalls. The most widely used test systems are micronucleus assays with meiotic cells of Tradescantia and with meristematic root tip cells of Allium and Vicia. In the last years, protocols for single cell gel electrophoresis assays have been developed, which can be conducted with a variety of species. Also various gene mutation test procedures have been developed with plants but they have hardly ever been used in environmental studies. Plants detect a broad variety of environmentally relevant genotoxins, in particular directly acting compounds. Many pesticides and industrial chemicals caused positive results; plant assays are also a unique tool for the detection of DNA‐reactive carcinogenic heavy metals in the environment. In many studies with complex mixtures, positive results were obtained which indicates that plants are sufficiently sensitive to detect effects without concentration of water samples. One of the shortcomings of the use of plants as indicators is their lack of sensitivity towards certain classes of promutagens such as nitrosamines, heterocyclic amines, and polycyclic aromatic hydrocarbons (PAHs). However, the former compounds are hardly encountered in the environment and PAHs can easily be detected chemically and in other mutagenicity tests. Taken together, the currently available data show that plant bioassays are a useful component of test batteries for environmental monitoring.  相似文献   

丽江7.0级地震前后滇西实验场的重力异常变化特征   总被引：7，自引：1，他引：7  

吴国华  罗增雄 《地震研究》1997,20(1):101-107

１９９６年２月３日，在云南省西北部的丽江县境内发生了一次Ｍｓ７．０级强烈地震。此次地震前后滇西实验场重力网共进行２７期流动重力观测，其重力变化的总体特征为：１．震中附近地区的丽江－剑川－洱源－带震前为下降变化，下降变化的幅值平均约３０×１０＾－８ｍｓ＾－２左右，震后重力变化继续下降；２．距震中稍远一点的渡口附近地区震前为持续上升变大，累计上升变化的最大幅值达１２３×＾－８ｍｓ＾－２，震后重力变化下  相似文献   

Benthic communities as influenced by nuclear testing and radioactive waste disposal off Novaya Zemlya in the Russian Arctic   总被引：1，自引：0，他引：1  

V. B. Pogrebov  S. I. Fokin  V. V. Galtsova  G. I. Ivanov 《Marine pollution bulletin》1997,35(7-12):333-339

On the material of sampling, accomplished in: (i) Chernaya Inlet of the Barents Sea (one of the flats of Novaya Zemlya Nuclear Test Site), (ii) in the Open Kara Sea and (iii) on the shoal off Novaya Zemlya from Stepovogo Fjord to Abrosimov Fjord (sites of radioactive waste disposal with activity 90% from total for the Kara Sea), characteristics of macro-, meio- and microbenthic bottom communities on the areas of potential radioactive danger are presented. Significant changes in macro- and meiobenthic communities are not revealed. In Chernaya Inlet, where three nuclear explosions were held in 1955–1961, disturbances in microbenthic protozoa communities are found. These disturbances expressed in the infusoria elimination from the fauna of the inlet deep-water sites and in morphological abnormality of this group individuals in population, inhabiting low depth of the inlet top. The assumed origin of revealed disturbances is high concentration (by 3–4 orders of magnitude above the background) of plutonium in bottom sediments of the inlet. Similar responses of the microbenthic flagellates are not detected.  相似文献   

自动气象站的动态试验及其测量准确度   总被引：10，自引：4，他引：10       下载免费PDF全文

郭锡钦  曾书儿 《应用气象学报》1994,5(2):176-183

计算了自动气象站动态对比试验结果的相关系数和差值误差区间，从而论证了对比试验的可信度。提出了计算自动气象站测量结果的标准差、合格率、准确度的方法。并用隐含周期分析与自相关模型得出了自动气象站的某些测量结果优于人工观测结果的结论。  相似文献   

Verification test of the mean event size model for moderate earthquakes in the Kanto region, central Japan     

M. Imoto  N. Yamamoto 《Tectonophysics》2006,417(1-2):131

In the Kanto region, there have been reports of decreasing b-values prior to earthquakes (M ≥ 5.5). The change of b-values is defined as the difference between the long- and short-term average earthquake magnitudes. A hazard function for moderately large earthquakes has also been proposed. This model was based on earthquakes that occurred between 1982 and 1999, and its effectiveness is measured retrospectively. In order to evaluate the effectiveness of the model through the use of independent data, the verification test is based on earthquakes observed after January 2000. Through the end of 2004, the only event where there was a decrease in mean event size was observed on June 3, 2000. This decrease resulted in a log-likelihood for the proposed model 1.3 units larger than that of the Poisson model, supporting the validity of the proposed model. Without accumulating further examples, we attempted to improve the verification test by expanding the study volume and by lowering the target cutoff magnitude in order to overcome the small sample size. When two other targets from the expanded volume were added, the difference in the log-likelihood (ΔlnL) increased to 3.6. In this case, the information rate per event was about 1.2, larger than that of the model period. Lowering the cutoff magnitude increased ΔlnL to 2.5. These extended tests led to higher confidence in the model with the larger ΔlnL value than did the primary test. From the viewpoint of the per-event information rate, each case involving targets with a magnitude 5.5 and larger resulted in better performance than in the model period.  相似文献   

Trial of earthquake prediction in Japan and a statistical test of time-shift     

Ken'ichiro Yamashina   《Tectonophysics》2006,417(1-2):169

Earthquake prediction was practiced in Japan to examine the hypothesis that “a pair of earthquakes with similar magnitudes may be a signal of an impending larger earthquake”. In the present study, predictions were announced with expected probabilities of 20–30% (rank A) or 10–20% (rank B). In 2001–2002, excepting the Ogasawara region, 26 and 6 cases among 61 and 30 predictions of ranks A and B, respectively, were successful. Based on a statistical test of time-shift, i.e., one-year shift in this paper, and averaged activity in 1990–1999, the success rate of 43% for rank A was shown to be greater than that expected by chance with a confidence level more than 99%. The success rate of 20% for rank B gave a corresponding confidence level of only about 40%, suggesting that the predictions of rank B were not confident in this period. According to the results, a statistical test of time-shift was found to be useful to evaluate the significance of prediction methods of this type.  相似文献   

Determination of undrained strength of fine-grained soils by means of SPT and its application in Turkey   总被引：1，自引：0，他引：1  

O. Sivrikaya  E. To?rol 《Engineering Geology》2006,86(1):52-69

The Standard Penetration Test (SPT) is one of the oldest and the most common in situ test used in soil explorations. In the recent years with the advent of new technology and techniques in determining the drawbacks in SPT, several researchers have attempted to correlate corrected field measured values with several soil properties. In this context, corrections applied to field values have become critical. In this study a questionnaire including the performance of the standard penetration test and equipment used in practice in Turkey is circulated in order to determine the relevant correction factors. Thus the appropriate corrections are used in acquiring corrected SPT-N values. The relationships between SPT-N and the undrained shear strength (S_u) are examined from the statistical point of view by taking the test types and SPT corrections into consideration, and comparison is made with previous studies. It is observed that SPT corrections play an important role on the obtained correlation equations. In addition, the importance of the effects of test types on the correlations is also emphasized. The Standard Penetration Test is found to be sufficient for reliable assessment of S_u.  相似文献   

陕西华清4#泉气体总量异常成因分析     

何崇君  王新  赵小茂  孟江峰 《山西地震》2007,(1):23-26

2006年7月下旬—9月初,陕西华清4#泉气体总量测值出现了一次低值异常。经调查落实,此次异常不是构造活动或地震前兆异常,而是由采样扩散瓶刻度指示体积与实际体积不符引起的。9月6日的扩散瓶封存气体刻度指示体积与实际体积误差试验以及9月9日—13日的气体总量对比观测试验均证实了这一结论。  相似文献