洞坪水库大沟湾滑坡体变形机制     

项伟  江洎洧  唐辉明  崔德山  黄玲 《地球科学》2009,34(5):855-860

大沟湾滑坡是瞿家湾滑坡群中相对高差最大的滑坡体, 洞坪水库蓄水后滑坡体产生了较大变形且变形机制表现出一定的特殊性.野外调查研究表明: 蓄水前该滑坡体稳定性良好; 蓄水至452m后, 滑坡后缘堆积体与基岩交界处产生贯通滑坡两侧冲沟的连续裂缝, 剪出口位于整个滑体中部580m高程附近, 由于下部坡体的抗滑作用而使整个坡体仍处于稳定状态; 蓄水至488m后, 从整个滑体前缘到570m高程附近又形成另一滑坡体, 与先前上部滑坡呈梯级分布, 分析得出大沟湾滑坡为上部牵引-下部推移的复合式滑坡, 两个滑坡共同作用导致整个滑体发生明显变形.分析并利用FLAC3D模拟再现整个变形过程, 对滑坡体变形破坏机制做出了很好解释.   相似文献   

高精度测量岩石样品Ce同位素组成的TIMS方法     

杨红梅  凌文黎  段桂玲 《地球科学》2009,34(6):939-945

介绍了对岩石样品的Ce同位素组成进行高精度测量的TIMS方法.采用α-羟基异丁酸(α-HIBA) 离子交换法分离和纯化岩石样品中的La、Ce元素, Ce同位素组成和La、Ce含量测定在Triton热电离质谱仪上完成.质谱标样JMC304的138Ce/142Ce比值统计值为0.0225762±0.0000015, 与大部分文献值一致.应用该方法对USGS玄武岩标样BCR-2和峨眉山玄武岩EQB的138Ce/142Ce比值和La、Ce含量进行了分析, 其结果分别为: 0.0225572±0.0000010、25.2±0.3μg/g、55.8±0.9μg/g和0.0225755±0.0000003、54.2±0.4μg/g、117.4±1.3μg/g.BCR-2的La、Ce含量测定结果与其证书值在误差范围内一致, 其分析精度为0.001%~0.005%.所有样品的140Ce/142Ce比值测定结果统计值为7.9439±0.0002, 介于文献最低值7.941与最高值7.947之间, 可能代表了该比值的最佳估计值.   相似文献   

北塘凹陷古近系沙河街组三段物源体系分析   总被引：6，自引：0，他引：6  

黄传炎  王华  周立宏  任培罡  刘军  白云风 《地球科学》2009,34(6):975-984

物源分析是盆地分析的重要内容之一.北塘凹陷古近系沙河街组三段(Es₃) 湖泊范围广、沉积厚度大, 而勘探程度低, 是大港油田未来勘探的重要突破区, 精细刻画北塘凹陷沙三段物源体系对沉积体系重建、有利区带预测具有重要意义.采用构造格架及古地貌宏观区分物源区与沉积区, 根据碎屑矿物组合特征划分物源区块, 依据地震反射特征勾绘物源在盆内进积方向, 利用砂体等厚图和砂地比等值线图精细描绘物源分支, 从不同角度、不同层次对北塘凹陷沙三段古物源体系进行精细研究.结果表明, 北塘凹陷物源来自北部燕山褶皱带和西部沧县隆起, 具体分为西部的沧县物源、西北角的汉沽物源、北部的大神堂物源和东北角的涧南物源.在物源体系和构造组合特征的控制下, 沙三段主要发育扇三角洲沉积体系.   相似文献   

Spatio-temporal point pattern analysis on Wenchuan strong earthquake     

Peijian Shi Jie Liu    Zhen Yang Agricultural College  Jiangxi Agricultural University  Nanchang  China China Earthquake Networks Center  Beijing  China 《地震学报(英文版)》2009,(3):231-237

For exploring the aftershock occurrence process of the 2008 Wenchuan strong earthquake, the spatio-temporal point pattern analysis method is employed to study the sequences of aftershocks with magnitude M≥4.0, M≥4.5, and M≥5.0. It is found that these data exhibit the spatio-temporal clustering on a certain distance scale and on a certain time scale. In particular, the space-time interaction obviously strengthens when the distance is less than 60 km and the time is less than 260 h for the first two aftershoc...  相似文献   

Ground motion attenuation relations of small and moderate earthquakes in Sichuan region   总被引：1，自引：0，他引：1  

Lanchi Kang    Xing Jin  Fuzhou University  Fuzhou  China Earthquake Administration of Fujian Province  China 《地震学报(英文版)》2009,(3):277-282

On the basis of 10 935 broadband velocity records of 135 earthquakes (ML3.0-6.4 and epicentral distance of 26-623 km) occurred from May 12 to June 10 in 2008, which are collected from 27 bedrock stations included in Sichuan Earthquake Monitoring Network, the corresponding acceleration records are obtained by a real-time simulation method. Then by regression analysis on the data, the relation between the peak ground acceleration and velocity attenuation of small and moderate bedrock earthquakes occurred in S...  相似文献   

Application of support vector machine to synthetic earthquake prediction     

Chun Jiang  Xueli Wei Xiaofeng Cui  Dexiang You Earthquake Administration of Tianjin Municipality  Tianjin  China Tianjin University of Technology  Tianjin  China 《地震学报(英文版)》2009,(3):315-320

This paper introduces the method of support vector machine (SVM) into the field of synthetic earthquake pre-diction, which is a non-linear and complex seismogenic system. As an example, we apply this method to predict the largest annual magnitude for the North China area (30°E-42°E, 108°N-125°N) and the capital region (38°E-41.5°E, 114°N-120°N) on the basis of seismicity parameters and observed precursory data. The corresponding prediction rates for the North China area and the capital region are 64.1% and ...  相似文献   

Effects of precipitation and landuse on runoff during the past 50 years in a typical watershed in the Loess Plateau, China   总被引：2，自引：0，他引：2  

Huaxing BI  Bin LIU  Jie WU  Lei YUN  Zhihan CHEN  Zhewei CUI Prof. in hydrology  College of soil  water conservation  Box  Beijing Forestry University  Qinghua East Road  Haidian District  Beijing  China  Researcher in hydrology  Xifeng station of soil  water conservation  Xifeng  Gansu Province  China Graduate Assis. 《国际泥沙研究》2009,24(3):352-364

In the past century, great progress has been made worldwide in our understanding of forest-water relationship. The successful forestation programs implemented in China-which have improved the ecological environmental conditions-have gained the attention of many researchers and highlighted the relationship between forestation and water yields. The arid and semi-arid Loess Plateau has received attention from water engineers and eco-hydrological researchers in China because of a shortage in water resources. We selected one of the oldest stations conducting soil and water conservation experiments, the Xifeng soil and water conservation station, and chose the Nanxiaohe catchment and its paired catchments （Yangjiagou catchment and Dongzhuanggou catchment） as our research areas. Trends in precipitation, air temperature, streamflow over the past 50 years, and the effect of changing land use on streamflow were analyzed. The Mann-Kendall test showed that precipitation had a negative trend （downward trend）, whereas air temperature showed a positive trend （upward trend） from the past to present in the Nanxiaohe catchment. However, the trends seen in precipitation, air temperature did not contain any ＂jumping points.＂ The paired catchment approach is used to detect the effects of land cover change on hydrology in the Yangjiagou and the contrast catchment, i.e., Dongzhuanggou catchment in our study. The results showed a large change in land use in the Yangjiagou catchment from 1954 to 2008. An increase in forested land （from 0% to 40.08% from 1954 to 2008） and a reduction of bare land （from 51.26% to 5.50% from 1954 to 2008） accounted for a large part of the change in land use. However, the land use changed little in the contrast catchment. The comparison of streamfiow in the paired catchments showed that forestation reduced streamflow by 49.63% （or 6.5 mm） each year.  相似文献   

Protection of bridge piers against scouring with tetrahedral frames     

Yee-Meng CHIEW 《国际泥沙研究》2009,24(4):385-399

Armoring countermeasures, such as riprap stones, are the primary method used to protect bridge piers against scouring; however, these methods have not had definitive success. Recently, flow-altering countermeasures, such as sacrificial piles, have been tested as an alternative to armoring countermeasures. This study investigated the mechanics of an innovative flow-altering countermeasure device, frames in the shape of tetrahedrons that act as a pier-scour countermeasure. Results of measured characteristics for turbulence flow showed that the flow around the tetrahedral frames can be divided into three regions： （1） a deceleration region near the sediment bed; （2） an acceleration region in the middle of water depth region; and （3） a restoration region near the water surface. The velocity magnitudes, turbulent intensities and vorticities decreased in the deceleration region, increased in the acceleration region and reverted to that of the unprotected condition in the restoration region. This pier-scour countermeasure is innovative because of its ability to dissipate energy associated with the downflow and the horseshoes vortex generated around the bridge pier. The scour tests revealed that the frames protected the foundation of bridge piers against scour. The experimental results showed that the percentage reduction of scour depth decreased as the velocity ratio, U/U c , decreased, reaching a value of 50% for the range of parameters tested in this study. Moreover, its efficiency was dependent on the placement density of the frames. The data showed that the frames were more effective when η was larger. However, their influence becomes less significant when η≥ 0.16.  相似文献   

Uncertainty analysis of CO_2 flux components in subtropical evergreen coniferous plantation     

LIU Min      HE HongLin  YU GuiRui  LUO YiQi  SUN XiaoMin & WANG HuiMin Institute of Geographic Sciences  Natural Resources Research  Chinese Academy of Sciences  Beijing  China  Gradute School of the Chinese Academy of Sciences  Beijing  School of Geography Science  Nanjing Normal University  Nanjing 《中国科学D辑(英文版)》2009,(2)

We present an uncertainty analysis of ecological process parameters and CO2 flux components (Reco, NEE and gross ecosystem exchange (GEE)) derived from 3 years’ continuous eddy covariance meas-urements of CO2 fluxes at subtropical evergreen coniferous plantation, Qianyanzhou of ChinaFlux. Daily-differencing approach was used to analyze the random error of CO2 fluxes measurements and bootstrapping method was used to quantify the uncertainties of three CO2 flux components. In addition, we evaluated different ...  相似文献   

Two new species of Vestrogothia (Phosphatocopina, Crustacea) of Orsten-type preservation from the Upper Cambrian in western Hunan, South China     

ZHANG HuaQiao  & DONG XiPing  School of Earth  Space Sciences  Peking University  Beijing  China  State Key Laboratory of Palaeobiology  Stratigraphy  Nanjing Institute of Geology  Palaeontology  Chinese Academy of Sciences  Nanjing 《中国科学D辑(英文版)》2009,(6)

Although fossils of Orsten-type preservation represented by Skaracarida and Phosphatocopina were first reported from the Middle and Upper Cambrian in western Hunan, South China in 2005, diversified phosphatocopine species have never been appropriately described and elucidated in terms of their evolutionary relationships. Here, we described two new species of Phosphatocopina, Vestrogothia anterispinata sp. nov. and V. bispinata sp. nov. The evolutionary relationship among all the valid species of Phosphatoco...  相似文献