大直径钢管桩土塞效应的判断和沉桩过程分析

港口工程和海洋工程中出现了越来越多的大直径超长钢管桩。由于这种桩直径较大,土塞的形成对桩的可打入性和承载力有较大的影响。鉴于此,根据大直径和超大直径钢管桩土塞性状的特殊性,考虑了桩直径对侧壁摩阻力、端阻力的影响,引入了尺寸效应系数,重新建立了土塞微分体的静力平衡方程,提出了采用改进的静力平衡法进行土塞效应判断,同时采用波动方程法近似模拟土塞与桩管内壁的相互作用,建立了简化的土塞与桩壁相互作用模型,并用该方法进行实际工程的打桩分析,分析结果表明该方法对土塞效应的判断、打桩过程的预测等与工程实测数据吻合较好。     

河口变形效应与涌潮的形成

作者采用非线性潮波方程,假定河口的宽度B(x)和深度h(x)是任意可微函数,导出了涌潮发生的条件,并讨论了各种变形情况下涌潮的形成。得出结论是,在涌潮形成过程中起决定作用的是浅水非线性效应,而河口变形效应则是起促进作用的。     

Mach Effect of Oblique Nonlinear Irregular Waves Interacting with Vertical Walls

Based on Hong‘s theory, previous random models, and a generalized expression suitable for FIT calculation, the interaction between irregular waves and vertical walls is numerically simulated. The results of simulation demonstrate that the wave energy changes with the incidence angle and the distance from the wall. Particularly, the Mach effect and the combined wave spectrum characteristics are analyzed in detail, which are significant in both theory and practice.     

海底地形测量波束角效应改进模型

在海洋测深过程中,回声测深仪波束角效应使记录的测深图像失真。现有波束角效应模型应用分段解析几何的方法将其划分为三个作用过程：测深值平移效应、双曲线增伪效应、深度丢失效应。在此基础上,应用微分几何的原理对波束角效应的空间结构及其数学原理描述进行理论分析,提出了波束角效应的改进模型及其改正算法。改进模型的优越之处在于提出决定波束角效应发生作用的是海底地形的线性特征而不是形状特征,由此提高了改正算法的自动化程度。     

蒽胁迫对2种海洋微藻的毒性效应

采用水生毒理学方法以及通过分析蒽对 2种海洋微藻的几种生理生化指标的影响 ,初步研究了蒽胁迫对 2种海洋微藻的毒性效应。结果表明 :随着蒽浓度的不断增大 ,1 2种海洋微藻的相对增长率逐渐降低 ,叶绿素 a和类胡萝卜素含量稍有下降 ,蒽对小新月菱形藻生长的 72 h· EC50为 2 51μg· L-1 ,蒽对亚心形扁藻生长的 72 h· EC50 为 387μg· L-1 ;2还原型谷胱甘肽 (GSH)含量逐渐降低 ;3加入外源性抗氧化剂 (GSH和甘露醇 )可缓解蒽胁迫所造成的 2种海洋微藻的细胞密度的降低 ,即可缓解蒽胁迫对微藻的毒害作用     

On the form factor scale effect

Four geosim families, with fully available resistance test results, have been re-analyzed to check the possible scale effect on the form factor. The form factor determined by Prohaska's method, with exponent n=4 and ITTC'57 correlation line, increases with the model size in all four cases analyzed. Because of its high correlation coefficient, a linear variation of the form factor with the scale is assumed. It is possible to have a first estimation of the ship's form factor extrapolating for λ=1 in the regression line. Form factor Reynolds number dependency will always be associated with a friction line. Using the ITTC'57 correlation line, the following equation K_S−K_M=1.91·(λ−1)·10⁻³ can be used to estimate the scale effect on the form factor. Calculations carried out, for axisymetric bodies, with some CFD codes are in good agreement with the experimental findings.     

低围压水平下砂的排水行为(英文)

采用干样沉降法制备样品 ,选用静三轴仪对松砂和密砂样在 10 k Pa至 10 0 k Pa的低围压下的排水行为进行了实验研究 ,并对实验结果作了橡皮膜校正 ,在围压为 10 k Pa的密砂实验中 ,轴向应力的校正值可达到 12 %。实验研究表明低围压下松砂的剪胀性非常明显 ,且存在剪应力极值 ;围压越低 ,松砂和密砂的剪应力极值越小 ,达到最大剪应力所对应的剪应变越小。同时还表明低围压范围内相对密度不同 ,砂的应力应变特性不同 ;此外 ,低围压下砂的内摩擦角高于高围压下的值 ,从而在工程上应重视低围压水平下砂土工程参数的合理选取     

声波对海洋生物的影响与作用的研究

本文研究了声波对某些海洋生物的影响与作用。实验表明，适当的声波剂量对海洋生物的作用所产生的声学生物效应是积极的，可促使生物体向有利的方向产生变异，而强度过大的声波对海洋生物有效伤甚至致死的效应。     

Topographic Effect of Izu Ridge on the Distribution of the North Pacific Intermediate Water South of Japan

The topographic effect of the Izu Ridge on the horizontal distribution of the North Pacific Intermediate Water (NPIW) south of Japan has been studied using observational data obtained by the Seisui-Maru of Mie University (Mie Univ. data) and those compiled by Japan Oceanographic Data Center (JODC data). Both data sets show that water of salinity less than 34.1 psu on potential density () surface of 26.8 is confined to the eastern side of the Izu Ridge, while water of salinity less than 34.2 psu is confined to the southern area over the Izu Ridge at a depth greater than 2000 m and to the southeastern area in the Shikoku Basin. It is also shown by T-S analysis of Mie Univ. data over the Izu Ridge that water of salinity less than 34.2 psu dominates south of 30°N, where the depth of the Izu Ridge is deeper than 2000 m and NPIW can intrude westward over the Izu Ridge. JODC data reveal that relatively large standard deviations of the salinity on surface of 26.7, 26.8 and 26.9 are detected along the mean current path of the Kuroshio and the Kuroshio Extension. Almost all of the standard deviations are less than 0.05 psu in other area with the NPIW, which shows that the time variation in the salinity can be neglected. This observational evidence shows that the topographic effect of the Izu Ridge on the horizontal distribution of the NPIW, which is formed east of 145°E by the mixing of the Kuroshio water and the Oyashio water, is prominent north of 30°N with a depth shallower than 2000 m.