A method analyzing deformation of anchor foundations in soft clay under static and cyclic loads

The paper presents a constitutive model to describe undrained cyclic stress-strain responses of soft clays based on the equivalent visco-elastic and creep theories. The hysteretic and nonlinear stress-strain responses of soft clays are described using the equivalent visco-elastic relationship and variations of the cyclic modulus and the damping ratio with the octahedral shear strain, respectively in the model. The cyclic accumulative strain is described using the Mises creeping potential function and the associated flow rule. The method determining the model parameters is given by static and cyclic triaxial tests. The finite element method to analyze deformation of anchor foundation in soft clay under static and cyclic loads is developed based on the model. For the method, a cyclic loading time history is divided into a series of incremental loading sub-processes which include one load cycle at least. The cyclic stress-strain responses of soil elements at any time are not tracked in detail and determined by the equivalent visco-elastic calculations for every loading sub-process. The accumulative deformation of anchor foundations is calculated using the initial strain algorithm. The method has been implemented in ABAQUS Software by developing interface programs. Model tests of the suction anchors are conducted and predicted using the method. Comparisons of predicted and model test results show that the method can be used to evaluate cyclic stability and reveal the failure process and mechanism of anchor foundations by analyzing deformation time-histories.     

基于GA-WNN的极化SAR海洋溢油检测方法研究

海洋溢油对海洋生态和人类生活带来严重的影响。由于合成孔径雷达(Synthetic Aperture Radar,SAR)具有全天时全天候的工作能力,在海洋溢油检测中发挥重要作用。目前,极化SAR是SAR探测技术的先进手段。本文利用6个极化特征进行溢油检测,通过对比分析这些特征对不同溢油的检测能力,得出单一极化特征在溢油检测中存在不足。通过J-M特征优选方法,提取出溢油检测识别度较高的特征影像,并利用遗传算法优化的小波神经网络(Genetic Algorithm-Wavelet Neural Network,GA-WNN)进行溢油检测。利用2套Radarsat-2全极化数据进行了方法验证,结果表明,该方法优于其他检测方法,溢油检测精度分别达到90.31%和95.42%。     

海洋发达国家海洋空间规划体系概述

海洋空间规划是重要的海洋空间管理工具,建构海洋空间规划体系是海洋生态文明建设的重要组成部分。文章对英国、比利时、荷兰、德国、挪威、美国、澳大利亚和智利等世界主要海洋发达国家的海洋空间规划体系发展状况进行概述,结果表明:各国已逐步形成基于各自国情、适应海洋行政管理体制的海洋空间规划体系,其中既存在"国家-区域-地方"的层级控制体系,也存在"战略-结构-使用"的内容控制体系,还存在"国家管辖与地方管辖并行"的独立自由型控制体系。可为我国生态文明建设下的海洋空间规划体系研究实践以及开展区域海洋管理工作提供参考。     

拉萨地块南部得明顶地区叶巴组火山岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其成因

作为拉萨地块南部形成时代最早的火山岩,叶巴组火山岩对于确定新特提斯洋的俯冲过程及印度欧亚大陆碰撞前的演化等具有重要意义。前人的研究结果显示,叶巴组火山岩是一套岩性由基性到酸性连续的、具有岛弧地球化学特征的火山岩。目前在叶巴组火山岩中只有酸性岩获得了精确的锆石U-Pb年龄,显示其形成时代为早侏罗世。然而对叶巴组中基性火山岩目前尚无精确的年代学报道。另外,有关叶巴组火山岩形成的动力学背景,目前还存在争议。对拉萨地块南部得明顶地区的叶巴组火山岩进行了锆石U-Pb年龄和地球化学研究,获得其锆石U-Pb年龄为188.8±1.8Ma,表明与酸性火山岩形成时代一致。得明顶地区叶巴组火山岩地球化学数据显示其具有类似于岛弧火山岩的特征,富集大离子亲石元素、亏损高场强元素、轻重稀土元素分异明显,部分样品具有Sr及Eu(δEu=0.75~0.83)的略微异常。结合前人的研究成果认为,叶巴组火山岩很可能形成于大陆边缘弧,其形成与新特提斯洋的北向俯冲有紧密的联系。     

Oxygen radicals production and actin filament disruption in bivalve haemocytes treated with benzo(a)pyrene

Haemocytes play an essential role in the internal defence of molluscs. It has been reported that organic xenobiotics commonly found as pollutants in the marine environment impair defence capabilities of haemocytes. The purpose of the present study was to investigate the effects of benzo(a)pyrene [B(a)P] on the integrity of the actin cytoskeleton and on endocytosis in haemocytes and to see if these effects are related to generation of reactive oxygen species. Haemocytes were exposed in vitro to B(a)P (0.5–40 μg/ml) for 1 h. Cell viability (using 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide or XTT assay) indicated that selected doses were sublethal. Uptake of neutral red was significantly decreased in a dose-dependent manner in B(a)P-treated haemocytes. Distribution of actin filaments, labeled with rhodamine-conjugated phalloidin, was altered in haemocytes treated with 20 or 40 μg/ml B(a)P. These effects could be related to an increased production of superoxide anion during B(a)P metabolism, as detected by the nitroblue tetrazolium (NBT) reduction assay in haemocytes treated with 10 μg/ml B(a)P.     

Spatio-temporal distribution of dissolved inorganic carbon and net community production in the Chukchi and Beaufort Seas

As part of the 2002 Western Arctic Shelf–Basin Interactions (SBI) project, spatio-temporal variability of dissolved inorganic carbon (DIC) was employed to determine rates of net community production (NCP) for the Chukchi and western Beaufort Sea shelf and slope, and Canada Basin of the Arctic Ocean. Seasonal and spatial distributions of DIC were characterized for all water masses (e.g., mixed layer, halocline waters, Atlantic layer, and deep Arctic Ocean) of the Chukchi Sea region during field investigations in spring (5 May–15 June 2002) and summer (15 July–25 August 2002). Between these periods, high rates of phytoplankton production resulted in large drawdown of inorganic nutrients and DIC in the Polar Mixed Layer (PML) and in the shallow depths of the Upper Halocline Layer (UHL). The highest rates of NCP (1000–2850 mg C m⁻² d⁻¹) occurred on the shelf in the Barrow Canyon region of the Chukchi Sea and east of Barrow in the western Beaufort Sea. A total NCP rate of 8.9–17.8×10¹² g for the growing season was estimated for the eastern Chukchi Sea shelf and slope region. Very low inorganic nutrient concentrations and low rates of NCP (<15–25 mg C m⁻² d⁻¹) estimated for the mixed layer of the adjacent Arctic Ocean basin indicate that this area is perennially oligotrophic.     

A new approximation for ocean waves propagating over a beach with variable depth

In this paper, the phenomenon of ocean waves propagating over a beach with variable water depth is re-examined. Based on the assumption of shallow water, a linearised shallow water equation is solved with an arbitrary beach profile. These irregular beach profiles form a set of partial differential equation with variable coefficient as the governing equation, which is the main obstacle in obtaining analytical solutions. In this paper, two families of beach profile are used as examples. A parametric study is conducted to investigate the influence of the beach profiles on the water surface elevation (η) and velocities (u).     

热带太平洋盐度变化:2015?2017年盐度异常

本文利用Argo海水盐度资料、海流同化数据和同期大气再分析数据,探讨热带太平洋盐度趋势变化和相关动力过程。Argo资料显示,2015?2017年热带太平洋出现显著的盐度异常(SAE),这是改变长期趋势的主要原因,表现为表层显著淡化和次表层咸化特征。这种盐度异常具有明显的区域性特征和垂直结构的差异,体现在热带太平洋北部海区(NTP)和南太平洋辐合区(SPCZ)表层淡化,盐度最大变幅为0.71～0.92,淡化可以达到混合层底;热带太平洋南部海区(STP)次表层咸化,最大变幅为0.46,主要发生在温跃层附近,期间盐度异常沿着等位密面从西向东扩展。平流和挟卷是与SAE密切相关的海洋动力过程,两者在NTP淡化海域有着持续而较为显著的影响,在SPCZ淡化、STP咸化海域后期贡献也较大,其中盐度平流对热带太平洋海区盐度变化起主要贡献。NTP淡化海区表层淡水通量和STP咸化海区密度补偿引起的混合也是SAE的重要影响因素。     

Distribution of radium-224 in the western Arctic Ocean

1Introduction ThephysicalcharacteristicsintheArcticOcean includewidecontinentalshelves,accountingfor36% oftheocean’ssurfacearea(MooreandSmith,1986) withseasonalicecover.Theprincipalwatersentering theArcticOceanarefromtheNorthAtlanticviathe FramStraitandtheBarentsSea,andtheNorthPacific viatheBeringStrait.Withinthearcticinterior,thewa- tersjoininthelarge-scalecirculationandaresubse- quentlymodifiedbyprocessesofair/sea/iceinterac- tion,riverinflow,andexchangewithsurrounding shelves.Howeve…     

北极海洋沉积物中持久性有机污染物分布特征及分子地层学记录的研究

持久性有机污染物(POPs)普遍存在于各种环境介质中,其中有机氯农药(OCPs)和多氯联苯(PCBs)化学性质稳定,在环境中能持久残留.它们经食物链浓缩并在生物体内累积,大多数具有致癌、致畸、致突变效应,构成对人类和生态系统的潜在危害,成为世界公认的全球性环境公害.