Geodynamic Evolution of the Eastern Segment of the Azores-Gibraltar Zone: The Gorringe Bank and the Gulf of Cadiz Region

Detailed structural interpretation of the recently acquired deep seismic multichannel profiles along the Iberian Atlantic Margins (IAM Project) provides new results on the geodynamic evolution of the eastern part of the Azores-Gibraltar plate boundary. Thrusting and folding of the oceanic basement and of Mesozoic and Cenozoic sedimentary cover of the Gorringe Bank region are consistent with the N–S convergence of Iberia and Africa. Compressive structures in the Gorringe Bank region are spread over a wide area. Deformation under compression took place mainly in Tertiary times, as is evidenced by a basal unconformity and several discontinuities in Tertiary sediments, although some deformation has also been recorded in Quaternary sediments. The compressive structures in the Gulf of Cadiz are E–W oriented thrusts, folds and related diapiric structures. N–S oriented transpressive deformation is likely to occur in the western Portuguese platform. There is no continuity of structures from the oceanic to the continental domain, suggesting that deformation transfers from one side to the other through a transcurrent fault zone. The fault contact between the two domains is located in the ocean-continent transition zone.     

北太平洋风海流季节变化的数值模拟

用绝热表层风海流模式,以1949～1979年COADS资料,研究北太平洋表层风海流及相应水位场随季节变化的特点、某些特定年表层风海流的异常。模式采用二次动量守恒的有限差分方法,保证了计算稳定性。在数值积分中考虑了陆界、水界条件和近岸地形对风海流及水位场的影响。计算表明:模式反映了北太平洋主要流系的季节变化规律,能较敏感地反映上层海洋对大气动力作用的响应。给出了北太平洋主要流系的强弱与黑潮大弯曲的对应关系。     

The Effect of Internal Fluid on the Response of Vortex-Induced Vibration of Marine Risers

Based on Iwan‘s wake oseillator model developed with the classical van der Pol equalion, the differential equation for the response of the vortex-induced vihration (VIV) of the riser considering the effect of the internal flowing fluid and the external marine environmental condition is derived. The effect of the intermal flowing fluid on the response of VIV of the riser is studied by means of the Finite Element Method. The results show that the effect of the internal fluid velocity on the VIV of the riser is strong when the natural frequency of the riser is close to the vortex shedding frequency. In addition, the increase of the top tension can decrease the sensitivity of the riser to the internal fluid velocity.     

台湾岛及其邻域地层和构造特征

台湾碰撞造山带作为世界上最年青的造山带之一，具有其独特的地质环境。它位于菲律宾海板块和亚欧板块的交汇处，东北面为东北-近东西走向的琉球沟-弧-盆系，东侧为西北向运动的菲律宾海板块，向南为近南北走向的吕宋岛弧，并与冲绳海槽和马尼拉海沟的形成演化密切相关，从而造就了众多形态复杂、成因各异的区域地层和构造现象。台湾岛自东向西可划分为海岸山脉带、台东纵谷、中央山脉、西部山麓带和沿海平原带五个构造-沉积单元。以台东纵谷为界，两侧在地形地貌、地层组成、岩石性质、重力、磁力等地质地球物理特征上均表现为明显不同，分别隶属于不同的板块构造单元，西侧属于欧亚板块的中国大陆边缘，东侧的海岸山脉带则是北吕宋火山岛弧的向北延伸。     

Stochastic Response Analysis of Piled Offshore Platform Excited by Stationary Filtered White Noise

In this paper,the analysis method of stochastic response of piled offshore platform excited bystationary filtered white noise is presented.With this method,the strong ground motion is considered asthree direction stationary filtered white noise process,the theoretic solutions of three special integrationequations are derived with the residue theorem,and the expression of response nodal displacements andmember forces of offshore platform excited by the stationary filtered white noise is put forward.Thestochastic response of a piled offshore platform excited by the stationary filtered white noise,which is lo-cated 114.3m in water depth,is computed.The results are compared with those obtained with the re-sponse spectrum analysis method and the stationary white noise model analysis method,and the corre-sponding conclusion is drawn.     

南海陆坡天然气水合物成藏的构造环境

南海是西太平洋最大的边缘海之一，其复杂的构造演化，形成了构造特征迥异的南海陆缘，有利于天然气水合物的发育，南海地区在中中新统以上发育了上中新统，上新统和第四系3套地层，3套地层所对应的地质时期的沉降速率在纵横向上的差别均较为悬殊，总体而言，南海第四纪整体沉降速率较大，为天然气水合物压力场环境的形成提供了有利条件，南海复杂的构造背景形成了丰富多彩的构造地质体，特定的构造地质体与水合物形成关系密切，这里讨论了滑塌体、泥底辟、增生楔等构造地质体在南海的分布情况，分析了上述构造体与气体水合物地震标志BSR之间的关系，以及特殊构造带在南海的展布规律，提出了特殊的造带中天然气水合物的成藏模式。     

A Study on Hydroelastic Response of Box-Type Very Large Floating Structures

The application of very large floating structure (VLFS) to the utilization of ocean space and exploitation of ocean resources has become one of the issues of great interest in international ocean engineering field. Owing to the advantage of simplicity in structure and low cost of construction and maintenance, box-type VLFS can be used in the calm water area near the coast as the structure configuration of floating airport. In this paper, a 3D linear hydroelastic theory is used to study the dynamic response of box-type VLFS in sinusoidal regular waves. A beam model and a 3D FEM model are respectively employed to describe the dynamic characteristics of the box-type structure in vacuum. A hydrodynamic model (3D potential theory of flexible body) is applied to investigate the effect of different dry models on the hydroelastic response of box-type structure. Based on the calculation of hydroelastic response in regular waves, the rigid body motion displacement, flexible deflection, and the short term and long     

海面对风应力的非定常响应

针对常垂直湍流系数和变垂直湍流系数两种情况，给出了开阔静止海面对风应力的非定常响应的解析表达式，并讨论了水深，风应力强弱对响应过程的影响，尽管没有考虑风场的非定常性，但本文的结果对理解海洋对风应力的非定常响应过程具有一定的帮助，对分析海面停风后的消衰过程也具有实际意义。通过与实测资料比较，认为垂直湍流系数模式要比常垂直湍流系数模式更为合理。     

单锚腿系泊系统动力计算的新方法

在Hamilton型拟变分原理体系下,建立了一种时间子域以三次和五次B样条函数插值的时间子域法,并将这种新方法用于单锚腿系泊系统的动力响应分析中。算例表明,新方法比传统的动力计算方法Wilson-θ法,在计算精度上有明显的优势,表明本方法能够用于计算单锚腿系泊系统的动力响应。