天津滨海地区浅层剪切波速与基底构造关系研究

Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0.01°×0.01°×1m grid. A shallow 3-D shear wave velocity structure of Tianjin coastal area is obtained. According to the data and geological background, we selected two typical velocity profiles to try to introduce and explain its relationship to basement structure. The results show that the shear wave velocity structure clearly presents the characteristic of stratification and lateral inhomogeneity. Furthermore, the difference of the shear wave structure between tectonic elements is clear and the velocity structure between the two sides of the local or border fault in the Quaternary is disturbed or affected significantly. It intuitively shows that the basement structure and fault activity of this region had good control of sedimentation development and strata formation in the Quaternary period which would have an important effect on engineering seismic and geological condition evaluation.     

华北克拉通中部过渡带SKS波分裂研究:鄂尔多斯东南角的局部软流圈绕流

本文对布设在华北克拉通东西两块体交界区域的宽频带流动地震观测台阵和部分固定台站的远震波形记录开展了SKS波分裂研究.结果显示,鄂尔多斯块体内部的各向异性比较弱,剪切波分裂导致的时间延迟一般小于0.7 s.鄂尔多斯块体东缘的山西断陷带和太行山以及华北平原西部均表现出了比较强的各向异性,时间延迟大于1.0 s.特别是在太行山地区观测到的ENE趋向的快波偏振方向明显不同于鄂尔多斯块体和华北平原地区的近E-W和ESE方向的快波偏振方向.在华北克拉通东西两块体交界过渡带的太行山地区观测到的显著上地幔各向异性及变化可能对应于围绕鄂尔多斯块体东南角的局部软流圈绕流,而后者可能起因于鄂尔多斯块体的逆时针旋转以及青藏高原软流圈沿秦岭大别造山带向东的流动.     

基于能量原理的粘滞阻尼器附加阻尼系数分配方法研究

以线性粘滞阻尼器加固剪切型规则框架结构为研究对象,基于能量原理提出附加阻尼系数正比于层间位移平方的分配方式。以六层和十二层钢筋混凝土框架为例,以确保结构在中震时保持弹性状态为设计目标,分别采用附加阻尼系数正比于层间位移平方的分配方式以及现有的分配方式,对结构进行消能减震设计。计算结果表明:有控结构均满足中震不坏的要求,层间位移角限值均未超过1/550,减震效果良好;附加阻尼系数正比于层间位移平方的分配方式得出的总阻尼系数最小,为最经济的设计结果。     

HOUGH变换在海浪遥感图像处理中的应用

本文提出了一种以FIOUGH变换为基础的海浪波长波向分析法,并对SEASAT合成孔径雷达获取的海洋遥感图像进行了方向和波长分析。该方法模拟人类纹理视觉机理,首先应用CFCM动态聚类方法对波峰、波谷和过渡带进行分类,然后采用随机行走模型对分类图像进行滤波,以获得整图的全局走向信息,再以此先验信息为先导对分类后的纹理图像进行定向跟踪拟合,得到代表海浪波峰的直线族图,最后在再对此图进行HOUGH变换和分析的基础上得到精确的波长与波向。     

The Linkage between Midwinter Suppression of the North Pacific Storm Track and Atmospheric Circulation Features in the Northern Hemisphere

The midwinter suppression(MWS) of the North Pacific storm track(NPST) has been an active research topic for decades. Based on the daily-mean NCEP/NCAR reanalysis from 1948 to 2018, this study investigates the MWS-related atmospheric circulation characteristics in the Northern Hemisphere by regression analysis with respect to a new MWS index, which may shed more light on this difficult issue. The occurrence frequency of the MWS of the upper-tropospheric NPST is more than 0.8 after the mid-1980 s. The MWS is accompanied by significantly positive sea-level pressure anomalies in Eurasia and negative anomalies over the North Pacific, which correspond to a strengthened East Asian winter monsoon. The intensified East Asian trough and atmospheric blocking in the North Pacific as well as the significantly negative low-level air temperature anomalies, lying upstream of the MNPST, are expected to be distinctly associated with the MWS. However, the relationship between the MWS and low-level atmospheric baroclinicity is somewhat puzzling.From the diagnostics of the eddy energy budget, it is identified that the inefficiency of the barotropic energy conversion related to the barotropic governor mechanism does not favor the occurrence of the MWS. In contrast, weakened baroclinic energy conversion, buoyancy conversion, and generation of eddy available potential energy by diabatic heating are conducive to the occurrence of the MWS. In addition, Ural blocking in the upstream region of the MNPST may be another candidate mechanism associated with the MWS.     

天水地震台最大振幅面波与初至波到时差和震中距的关系

根据天水地震台ＳＫ地震仪近年来记录的３３８个震例的资料,用最小二乘法求出最大振幅面波与初至波至时差同震中距的关系式,并与Ｊ－Ｂ表进行了对比,结果表明,用Ｊ－Ｂ表计算出的震中距与实际震中距的偏差较大,用本给出的关系式和走时表估算震中距可以缩小误差,提高定位精度。     

Wave diffraction on arc-shaped floating perforated breakwaters

An analytical method is developed to study the sheltering effects on arc-shaped floating perforated breakwaters. In the process of analysis, the floating breakwater is assumed to be rigid, thin, vertical, and immovable and located in water with constant depth. The fluid domain is divided into two regions by imaginary interface. The velocity potential in each region is expanded by eigenfunction in the context of linear theory. By satisfying continuity of pressure and normal velocity across the imaginary fluid interface, a set of linear algebraic equations can be obtained to determine the unknown coefficients for eigenfunction expansions. The accuracy of the present model was verified by a comparison with existing results for the case of arc-shaped floating breakwater. Numerical results, in the form of contour maps of the non-dimensional wave amplitude around the breakwater and diffracted wave amplitude at typical sections, are presented for a range of wave and breakwater parameters. Results show that the sheltering effects on the arc-shaped floating perforated breakwater are closely related to the incident wavelength, the draft and the porosity of the breakwater.     

杭州湾中部实测波浪特性分析

利用杭州湾中部一年实测波浪资料,分析该地区的波参数统计变化特性,采用最小二乘法拟合得出相关参数之间的关系式,并统计分析了频谱特性。结果表明:杭州湾中部以小浪和轻浪为主,在各月分布较为均匀,年平均周期为2.97 s;最大一次波浪过程为冷空气影响所致,影响强度大于台风莫拉克;常浪向分布在东北至东南向,其中又以小浪出现较多,对应的波周期以2~4 s为主;强浪向主要分布在西北和东北方向,对应的波周期主要分布在3~5 s;多数特征波参数之间相关关系较好;由谱分析得知风浪占多数,且以单峰为主。研究结果可为相关工程和理论研究提供基础资料。     

浅论不同应力状态下坝基层间剪切带弹性力学性质

本文以万家寨水利枢纽坝基Ｓｃｊ０８层间剪切带声波测试资料为依据,论述了不同应力状态下、剪切带弹性力学性质变化过程和机理,其成果对坝基施工过程控制和基础稳定性分析具有一定指导意义。     

南极长城站地壳和上地幔各向异性分析

利用我国第24次和第25次南极科学考察队于2008年2月—2010年3月南极长城站记录到的地震事件数据进行剪切波分裂研究. 选取近震事件对Sg波进行剪切波分裂计算,结果表明快波偏振方向有两个,分别为北东向和近南北向; 慢波延迟时间的范围为1.45—5.17 ms/km,平均值为3.54 ms/km.同时选取长城站记录到的远震数据SKS波震相进行剪切波分裂计算,得出上地幔快波偏振方向优势取向为北东向, 慢波延迟时间平均值为1.60 s. 剪切波分裂结果显示长城站地区地壳和上地幔具有明显的各向异性, 并显示长城站地区地壳与上地幔快波偏振方向几乎平行,表明壳幔变形的一致关系.另外,地壳和上地幔各向异性的快波偏振方向不仅与长城站附近的海沟方向平行,同时也与绝对板块的运动方向平行.该结果进一步说明了绝对板块的运动是构成上地幔各向异性的主要原因.