辽东湾S2冰侧限剪切强度的试验研究   总被引：3，自引：0，他引：3  

李志军孟广琳  高树刚刘培林 《海洋工程》2002,20(1):20-23

利用试验方法系统地研究了辽东湾S2型海冰侧限剪切强度随剪切应变速率、加载方向、法向应力、温度和冰内孔隙率的变化规律。介绍了S2型海冰各向异性特点及剪切应变速率对剪切破坏方式的效应和韧脆破坏转变的条件。分析了不同加载方向海冰峰值剪切强度的差异 ,获得 - 6 2℃温度下S2冰内摩擦角和内聚力分别为 42°和 70 0kPa。利用统计分析给出峰值剪切强度与冰温和孔隙率的试验关系  相似文献   

Gradation affects basic mechanical characteristics of Chinese calcareous sand as airport subgrade of reefs     

Shen Yang  Xue Shen  Hanlong Liu  Huayang Ge  Xiaoxi Rui 《Marine Georesources & Geotechnology》2020,38(6):706-715

Abstract

Construction of the reefs in the South China Sea is a significant foundation to the secure stability and economic development of China. The construction of an airport runway is necessary for this realization. The calcareous sand is the main primary material in the runway construction. A certain type of calcareous sand near a certain reef of the South China Sea was studied in this paper. To investigate this specific calcareous sand, quartz sand was used as a reference for comparison. Microscopic 3-D imaging, compression and triaxial tests were conducted to test the micro, squeezing and shear properties. The effect mechanism of gradation on the calcareous sand’s compressibility and shear characteristics are discussed from a mesoscopic viewpoint using 3-D morphology. Calcareous sand particles are multiangular and flatter in comparison with quartz sand. The larger the particle sizes are, the more different the two sands’ morphologies are. The compressibility of calcareous sand is greater, and the effect of the coarse fraction (5–1?mm) content in the gradation plays the most significant role in this feature. When the coarse particles’ content is less than 25% and the mass ratio of the middle and fine particles (M) is constant, there is the worst coarse fraction content causing the calcareous sand to be most likely compressed. The worst coarse fraction content decreases with the increase in M, and an empirical formula is proposed. When the gradation, relative density and confining pressure are the same, the peak shear stress and strain of calcareous sand are all at a high level. The effect of confining pressure is manifested in calcareous sand. The shear strength and dilation of calcareous sand are also most affected by the medium coarse fraction (5–0.25?mm) content.  相似文献   

一种新型混沌遗传优化算法的研究     

张海燕  潘成欣 《中国海洋大学学报(自然科学版)》2006,36(4):555-558

在对遗传算法交叉、变异后结果的处理方法进行改进并在将进化过程分段的基础上,提出1种新的混沌遗传算法。该算法利用混沌运动的遍历性择优产生初始群体,对每一轮遗传操作所得到的部分当前最优个体进行变尺度混沌搜索。仿真结果表明,该算法具有较高的优化效率,并能求得全局最优解。  相似文献   

Habitat characteristics and spatial arrangement affecting the diversity of fish and decapod assemblages of seagrass (Zostera marina) beds around the coast of Jersey (English Channel)     

Emma L. Jackson  Martin J. Attrill  Malcolm B. Jones 《Estuarine, Coastal and Shelf Science》2006,68(3-4):421

Recent research and management plans for seagrass habitats have called for landscape level approaches. The present study examines the spatial utilisation of subtidal seagrass beds by fish and decapods around the coast of Jersey (49°N 02° W). A hierarchical scale of landscape configuration and the plant characteristics of eight seagrass beds were measured and the contributions of these variables as predictors of the properties of the fish and decapod assemblages were evaluated using multiple linear regression models. The results indicated that total diversity had a negative relationship with transect heterogeneity and total species number had a weak negative association with increasing fragmentation. Both total diversity and total species number showed a positive relationship with depth. In fact, in all models of species number and densities, values were higher in deeper seagrass beds. Total decapod density increased with aggregation of seagrass patches within a landscape. In addition to landscape configuration, smaller-scale structural changes in both canopy height and epiphyte load appeared to influence densities of decapod crustaceans. At night, fewer patterns could be explained by the independent variables in the model.  相似文献   

具有内波特性的渤海南部次重力波     

范植松  高郭平  尹训强  范宇  吴玮 《海洋学报》2003,25(5):136-140

次重力波(infragravity waves)是频率范围介于局地平均Brunt-V¾is¾l¾频率和0.05Hz(涌浪频率)之间的一种海洋波动,其能量在深水大洋中一般甚低,但在浅海中却很强.该波动的研究对于浅海海洋内部混合、近岸海洋工程、海洋生态学、海洋沉积学及军事海洋学均有重要的意义.Munk[1]很早就开始研究这类波动,然而主要由于观测技术的限制,对于该类波动的动力学机制的研究进展迟缓.  相似文献   

A Preliminary Study of Shear Wave in Seafloor Surface Sediments   总被引：1，自引：0，他引：1  

Bo Lu  Ganxian Li  Shaojian Huang 《Marine Georesources & Geotechnology》2006,24(1):17-28

This article preliminarily reports and analyses the transmission characteristics and behaviors of shear wave in the offshore seafloor surface sediments in China, discusses the relationships between the physical and mechanical features of the shear wave and the compression wave, and compares the testing results with that of Hamilton and Chen et al. The result shows that the shear wave can be tested if the seafloor surface sediment has tangent modulus. The shear wave velocity ranges from 50-600 m/s and the measuring frequency from 50-200 kHz. The sound velocity rate of shear wave and compression wave can be used to appraise the stress-strain feature of seafloor surface sediments. This study provides a basis for further describing and appraising the seafloor sedimentary acoustic-mechanical feature and building a geological-acoustic model on China's offshore sea area.  相似文献   

0220号热带风暴(米克拉)特征分析     

李孟植 《海洋预报》2003,20(3):7-11

南海是热带气旋活动较为频繁的地区之一。该地区因其独特的地理环境和复杂的热带大气环流系统，在热带气旋预报工作上存在一定的困难。本文在分析一些气象图表资料的基础上，对2002年第20号热带风暴(米克拉)的形成、发展及消亡进行了探讨和研究。主要从形成的背景环流，气旋的结构等方面入手，总结出一些该气旋所具备韵特有流场，从而为以后的南海自生热带气旋预报工作积累一定经验。  相似文献   

海洋旅游研究初探   总被引：7，自引：0，他引：7  

李平  盛红 《海岸工程》2001,20(1):58-63

海洋旅游在我国发展迅猛 ,但对海洋旅游的研究明显滞后。就海洋旅游的基本概念、研究范围、特点、开发类型及开发原则等基础理论问题提出了自己粗浅的认识 ,以求引起更多的学者关注这一领域的研究 ,进行更加有益的探讨  相似文献   

海底浅层介质切变波的初步研究   总被引：2，自引：0，他引：2  

卢博  李赶先  黄韶健 《热带海洋学报》2004,23(4):11-18

初步分析了中国沿海海底浅层介质切变波的传播特性,讨论了多种海底浅层介质切变波与压缩波、物理力学性质之间的关系,并与Hamilton和Chen等人的结果进行了比较。认为海底浅层介质存在切变模量,切变波可以被测量出来,切变波速为50—600m·s-1,测量频率在50—200kHz之间,用波速比可以评价海底浅层介质的应力 应变性质。研究工作有助于描述和评价中国沿海海底浅层介质声学物理性状,并为最终建立中国沿海海底地声模型提供依据。  相似文献   

黑鲷早期鳞被的形成     

丁彦文  李加儿  区又君 《热带海洋学报》1991,(3)

黑鲷Sparus macrocephalus(Basilewsky)幼苗鳞被最早出现的部位是在躯干部胸鳍基后至肛门直上方的侧线处。黑鲷只具一个鳞被起始中心。最早出现鳞片的个体为体长9.5—14.1mm,平均11.51±0.85mm,全长11.2—16.5mm,平均13.65±1.01mm,孵后日龄23—35d。鳞被发育完全时的最小个体为体长12.1—18.5mm,平均14.57±1.55mm,全长14.8—23.5mm,平均17.99±2.17mm,孵后日龄27—42d。  相似文献