关于悬沙级配沿垂线分布的有效悬浮指标

讨论了要流悬沙中某级泥沙所占全体悬沙之Ｐｉ的两种定义,根据Ｈ．Ｒｏｕｓｅ含沙量分布公式,导出了相应的Ｐｉ／Ｐａ、Ｐｉ／Ｐｉｐｊ、Ｐｉ／ＰｉｐｊＱ等３种形式的悬沙级配沿垂线相对分布表达式;表达了有效悬浮δｉ的物理函义及其实际应用取值问题。     

RIVERS' FEATURES ON ALLUVIAL FANS IN NORTHWEST CHINA

IINTRODUCTIONAlluvialfanisakindofsedimentogeniclandform,whichisdevelopedwhereriverflowsoutofmountain.Holdingapositionalongfootsofmostmountains,itconstittltestheimportantpartofthefluvialsedimentarysystem.Hooke(1967)describedtraditionalriverformonalluvialfans.Riversinciseandformdeepstableandunstablechannelsonupperpartsofalluvialfans.Andbelowtheintersectionpoints,riversflowoutofthevalleysinformofbraidedchannelanddepositsmallsecondaryajlluvialfansonthesurfaceofthefan.Lobeck(1939,fromRochocki…     

考虑桩顶冠梁效应的水泥土挡墙变形计算方法

以ｍ法为基础,建立了考虑桩顶冠梁效应的挡墙变形计算模型,给出了计算公式。工程实例表明：该方法预测挡墙变形是可行的。     

打桩振动环境效应的有限元-无限元耦合分析

把打桩引起的近场波动的数值模拟问题归结为层状半无限弹性体系的动力响应问题,采用有限元与无限元的耦合模型对该问题进行数值模拟,最后对整体模型时空离散,用Ｃ语言编制计算机程序,利用该程序对上海某高层办公楼进行实例计算,并与实测结果进行比较分析,表明该方法是可行的,可为打桩施工的安全作业提供依据。     

白斑综合症杆状病毒在养殖万氏对虾(Penaeus vannamei)中暴发流行和人工感染研究

白斑综合症杆状病毒(White spot syndrome baculovirus,WSBV)对万氏对虾有较强的致病力,在病虾被感染的2～3d内,就可以使万氏对虾死亡率达83.3%～90%.WSBV对万氏对虾的鳃上皮细胞、甲壳下表皮细胞、胃上皮组织细胞、肌细胞、结缔组织细胞和中肠基底膜下肌细胞以及结缔组织细胞敏感.在细胞质中的完整杆状病毒粒子大小为(129～164)nm×(365～412)nm,在细胞核中的完整杆状病毒粒子大小约为(135～176)nm×(429～480)nm.万氏对虾对wSBv没有明显的抗病性,60d养殖死亡率达90%.     

川西甲基卡地区西康群砂岩地球化学特征及对物源区、构造背景的指示

松潘-甘孜造山带中部大面积分布西康群浊积岩,为一套厚度巨大(2000～3000 m)的泥质碎屑复理石建造,以深海-次深海海底扇沉积为特征.本文通过对甲基卡稀有金属矿集区分布的西康群砂岩进行主量元素、微量元素及粒度分析,从而揭示该区砂岩构造背景和物源属性.研究结果表明,砂岩样品SiO2、CaO、MgO、Al2 O3、Fe...     

Sedimentary characteristics and genetic mechanism of the giant ancient pockmarks in the Qiongdongnan Basin,northern South China Sea

In the late Miocene, giant ancient pockmarks, which are fairly rare globally, developed in the Qiongdongnan Basin. In this paper, to determine the sedimentary characteristics and genetic mechanism of these giant ancient pockmarks in the Yinggehai Formation of the Qiongdongnan Basin, based on high-resolution 3D seismic data and multiattribute fusion technologies, we analyzed the planar distribution and seismic facies of the ancient pockmarks and compared the characteristics of the ancient pockmar...     

Aliphatic biomarker signatures of early Oligocene-early Miocene source rocks in the central Qiongdongnan Basin: Source analyses of organic matter

The geochemical signatures of fifty-four rock samples and three supplementary drill stem test(DST) oils from the Yacheng-Sanya formations in the central Qiongdongnan Basin(CQB) were analysed. Reconstruction of the early Oligocene-early Miocene(36–16 Ma) palaeovegetation and source analyses of organic matter(OM) were conducted using aliphatic biomarkers in ancient sediments and DST oils. Both the interpreted aquatic and terrigenous OM contributed to the CQB source rocks(SRs) but had varying relat...     

近太湖新银鱼——银鱼移植新对象

近太湖新银鱼不仅在形态上与太湖新银鱼很相似,而且它们的个体大小、生长速度、食性等方面也十分相近。近几年在湖北地区的湖泊、水库相继发现了近太湖新银鱼,并在湖北省广水市徐家河水库成为优势种类,形成了较大生产规模。从目前研究的结果来看,近太湖新银鱼也是适宜我国湖泊、水库移植的银鱼种类。     

Probability density evolution method for seismic liquefaction performance analysis of earth dam

To investigate the seismic liquefaction performance of earth dams under earthquake loading, we present a new methodology for evaluating the seismic response of earth dams based on a performance‐based approach and a stochastic vibration method. This study assesses an earthfill dam located in a high‐intensity seismic region of eastern China. The seismic design levels and corresponding performance indexes are selected according to performance‐based criteria and dam seismic codes. Then, nonlinear constitutive models are used to derive an array of deterministic seismic responses of the earth dam by dynamic time series analysis based on a finite element model. Based on these responses, the stochastic seismic responses and dynamic reliability of the earth dam are obtained using the probability density evolution method. Finally, the seismic performance of the earth dam is assessed by the performance‐based and reliability criteria. Our results demonstrate the accuracy of the seismic response analysis of earth dams using the random vibration method. This new method of dynamic performance analysis of earth dams demonstrates that performance‐based criteria and reliability evaluation can provide more objective indices for decision‐making rather than using deterministic seismic acceleration time series as is the current normal practice. Copyright © 2016 John Wiley & Sons, Ltd.