淮河大堤老应段土体蠕变特性研究及工程应用   总被引：3，自引：0，他引：3  

马金荣  姜振泉 《工程地质学报》1997,5(1):53-58

本文依据工程需要, 采取淮河大堤老应段的原状和扰动土样, 在室内对堤体及堤基土的剪切蠕变和拉伸蠕变特性进行了试验研究。粘土的蠕变剪切强度远低于瞬时剪切强度, Ｃ值仅是Ｃ值的４０％左右;相同含水条件下粘土的长时抗拉强度大于瞬时抗拉强度, 长时拉伸应变量远大于瞬时拉伸应变量, 约为２倍。  相似文献   

多层次格点资料相似离度动态综合做广东多站点长期趋势预报     

李开乐 《热带气象学报》1997,13(2):180-185

介绍一种长期趋势预报方法，该法结合预报经验，按照形势变化特征对５００和１００ｈＰａ高度，太平洋海面温度等多层次月平均格点资料进行分区统计，然后用相似离度理论做计算。其中，既同时考虑空间多层次的气象信息，又从连续几个月的信息变化去进行动态的相似综合，力图使相似比较中的片面性得到改善。  相似文献   

“4.12“强沙尘暴天气中期分析   总被引：3，自引：0，他引：3  

高凤荣  吉惠敏  宋秀玲 《干旱气象》2001,19(2):31-33

从中期预报的角度,对2000年4月12日甘肃河西中东部强沙尘暴天气过程的环流演变特征、波谱特征以及冷空气活动等方面,进行了初步分析.分析结果表明,这次强沙尘暴天气是在2波转1波的环流调整中生成长波槽,其后又在1波转2波,3波增幅的情况下,由长波槽调整造成的.  相似文献   

Multiple ruptures for Long Valley microearthquakes: a link to volcanic tremor?     

A. Stroujkova  P. Malin 《Journal of Volcanology and Geothermal Research》2001,106(1-2)

Despite several episodes of ground deformation and intense seismic activity starting in 1978, the Long Valley, California, volcanic area has not produced clearly recognized volcanic tremor. Instead, a variety of atypical microearthquakes have been recorded during these episodes, including events dominated by low-frequency (long-period) or mixed high and low-frequency (hybrid) signals. During a 1997 episode, a number of unusual microearthquakes occurred within a temporary 40-station seismic network surrounding the Casa Diablo area, allowing the events to be precisely located and analyzed as a function of azimuth, offset, and source characteristics. Eight prime examples lie within two, 7 km-deep clusters of seismicity separated by about 1 km, with four events in each cluster. Empirical Green's function deconvolution shows that these events are composed of two to three sub-events, the sub-events consisting of ordinary (single rupture, double-couple) microearthquakes. The delay times between the sub-events are constant within each cluster, equaling 0.092 s in one and 0.06 s in the other. Events from other clusters show similar delays. The signal interference produced by the closely spaced sub-events gives rise to modulated, delay-dependent source spectra. The regularity of the delays suggests that the sub-events are being triggered by a fixed length and/or time scale process, an example being the length/inflation rate of a magmatic or hydrothermal flow structure. With continued action of the triggering process, the sub-events could proliferate and evolve into observable volcanic tremors at Mammoth.  相似文献   

Spatial / Temporal Features of Antarctic Climate Change     

Ge Ling  Liang Jiaxing  Chen Yiliang 《大气科学进展》1996,13(3):375-382

Bused on January 1962-October 1993 mean value series of monthly mean temperature anomalies of 16 Antarctic stations on 10 standard isobanc surfaces from the surface to the 30 hPa,long term trends and periodic features of climate changes from the troposphere to the lower stratosphere over the Antarctic region are investigated by maximum entropy power spectrum analysis,and the relation between climate change of the stratosphere (troposphere) and tolal ozone (southern 500 hPa circulation) is discussed.  相似文献   

Seepage measurements from Long Lake,Indiana Dunes National Lakeshore     

S. A. Isiorho  F. M. Beeching  P. M. Stewart  R. L. Whitman 《Environmental Geology》1996,28(2):99-105

 Long Lake, located near Lake Michigan within the dune-complexes of Indiana Dunes National Lakeshore, USA, was formed some time during the Pleistocene and Holocene epochs. A surficial aquifer underlies Long Lake, which is either a source or sink for the later. The hydrologic processes in the lakeshore and surrounding environs have been significantly altered during the agricultural, municipal, and industrial development of the region. Limited data suggest that the organisms of Long Lake have elevated levels of several contaminants. This study attempts to quantify seepage within the lake to assess the potential threat to groundwater quality. Seepage measurements and minipiezometric tests were used to determine seepage within the lake. Seepage measurements and minipiezometric tests suggest that water seeps out of Long Lake, thus recharging the groundwater that flows southwest away from the lake. There is a great deal of variability in the seepage rate, with a mean of 11.5×10^–4±11.2×10^–4 m d^–1. The mean seepage rate of 0.3 m yr^–1 for Long Lake is greater than the 0.2 m yr^–1 recharge rate estimated for the drainage basin area. The Long Lake recharge volume of 2.5×10⁵ m³ yr^–1 is approximately 22% of the volume of the lake and is significant when compared to the total surface recharge volume of 4.8×10⁵ m³ yr^–1 to the upper aquifer of the drainage area. There is a potential for contamination of the groundwater system through seepage from the lake from contaminants derived from aerial depositions. Received: 16 August 1995 · Accepted: 18 September 1995  相似文献   

铼—锇同位素分析中样品的预处理   总被引：4，自引：3，他引：4  

谢智  张巽 《岩矿测试》1997,16(4):284-288

文章对近年来在Ｒｅ＿Ｏｓ同位素质谱分析中样品的预处理方法进行了介绍和总结评述，重点介绍了样品的分解和元素的分离纯化。引用主要文献１８篇。  相似文献   

空间波与长试样法测量介电常数的结果与对照   总被引：5，自引：0，他引：5  

陈志雨  李安莱  周冬青 《遥感学报》1997,1(1):40-45

用空间波法测量无限大半空间模拟介质板的复介电常数 ,包括金属板定标法与双极化法 ,测量中同时接收前向散射的振幅和相位 ,实验在X波段进行。该文的金属板定标法本质上是自由空间中的长试样法 ,并对它的原理和测试结果与波导长试样法作了比较与对照  相似文献   

地理信息系统与主成分分析在多年气象观测数据处理中的应用   总被引：7，自引：0，他引：7  

李本纲  陶澍  林健枝  程寿全 《地球科学进展》2000,15(5):509-515

探讨一种处理多年气象观测数据的新方法,该方法以地理信息系统为技术支撑,以数字图像处理和标准主成分分析为核心,适用于处理空间分布广、时间序列长的多类型气象观测数据。在实例研究中,首先对中国160个站10年气温、降水观测数据进行空间双线性插值,得到一系列数值图像;并对这些数值图像进行标准主成分分析,得到反映多年气候状况且相互独立的各主成分;然后选取其中前6个主成分进行空间迭代聚类分析,得到中国气候分类图;通过对所得类别进行多年气候指标统计分析,得到中国气候区划图;最后将所得气候区划图与传统气候区划图进行比较分析,并指出该方法在处理多年气象观测数据工作中的可行性与局限性。  相似文献   

The potential of sampling with partial replacement for fisheries surveys     

Warren  William G. 《ICES Journal of Marine Science》1994,51(3):315-324

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