A semi-analytical solution for random wave-induced soil response and seabed liquefaction in marine sediments     

Haijiang Liu  Dong-Sheng Jeng   《Ocean Engineering》2007,34(8-9):1211-1224

In this study, unlike most previous investigations for wave-induced soil response, a simple semi-analytical model for the random wave-induced soil response is established for an unsaturated seabed of finite thickness. Two different wave spectra, the B-M and JONSWAP spectra, are considered in the new model. The influence of random wave loading on the soil response is investigated by comparing with the corresponding representative regular wave results through a parametric study, which includes the effect of the degree of saturation, soil permeability, wave height, wave period and seabed thickness. The maximum liquefaction depth under the random waves is also examined. The difference on the soil response under the two random wave types, B-M and JONSWAP frequency spectra, is also discussed in the present work.  相似文献   

Multi-scale spatial variability in fish assemblages associated with Posidonia oceanica meadows in the Western Mediterranean Sea     

Joan Moranta  Miquel Palmer  Gabriel Morey  Ana Ruiz  Beatriz Morales-Nin 《Estuarine, Coastal and Shelf Science》2006,68(3-4):579

  相似文献   

The buckling of a corrugated carbon fibre cylinder under external hydrostatic pressure     

Carl T. F. Ross  Andrew P. F. Little 《Ocean Engineering》2001,28(9)

A theoretical and an experimental investigation was carried out, where a carbon fibre corrugated circular cylinder was tested to destuction under external hydrostatic pressure. The theoretical investigation was via the finite element method, where the structure was modelled with several orthotropic axisymmetric thin-walled shell elements. The experimental observations were aided with strategically placed strain gauges. Comparison between theory and experiment showed that the experimentally observed buckling pressure was a little lower than the theoretical prediction. This may have been due to the fact that the model had slight initial geometrical imperfections in the circumferenential direction.  相似文献   

常压法合成Methomyl的研究     

钱佐国  孙明昆  杨福顺  孙林枫  周曾昊 《中国海洋大学学报(自然科学版)》1990,(3)

提出一种合成Methomyl的改良法。该方法的特点是反应可在常压下进行。对常压反应的优宜条件作了系统研究,并讨论了反应机理。  相似文献   

Wave interaction with a submarine pipeline in clayey soil due to random waves     

A. Vijaya kumar  S. Neelamani 《Ocean Engineering》2005,32(13):1517-1538

The wave pressure and uplift force due to random waves on a submarine pipeline (resting on bed, partially buried and fully buried) in clayey soil are measured. The influence of various parameters viz., wave period, wave height, water depth, burial depth and consistency index of the soil on wave pressures around and uplift force on the submarine pipeline was investigated. The wave pressures were measured at three locations around the submarine pipeline (each at 120° to the adjacent one). It is found that the wave pressure and uplift force spectrum at high consistency index of the soil is smaller compared to that of low consistency index. Just burying the pipeline (e/D=1.0) in clayey soil reduces the uplift force to less than 60% of the force experienced by a pipeline resting on the seabed (e/D=0.0) for I_c=0.33.  相似文献   

辽河盆地大民屯凹陷流体压力特征   总被引：1，自引：0，他引：1  

叶加仁  郝芳  陈建渝  陈振岩 《海洋地质与第四纪地质》2003,23(4):83-94

大民屯凹陷是辽河断陷内4个下第三系凹陷之一。在综合利用钻井、试井及地震等资料的基础上，系统研究并论述了大民屯凹陷流体压力特征。基于57口井的声波测井资料，凹陷内泥岩压力特征可区分为正常压力、异常压力或强超压等类型；根据152口井391个点的压力测试数据，凹陷内产油层段的压力梯度多接近于1；利用公式法模拟计算了47条地震剖面的流体压力、剩余压力及压力系数的分布特征，凹陷内剖面压力系统自上而下一般由正常压力、弱超压和强超压3部分组成。此外，还根据流体压力演化的基本原理及钻井、岩性与试井等实际资料，模拟恢复了大民屯凹陷的压力演化史，其可划分为超压原始积累、超压部分释放及超压再积聚3个阶段。总体上，大民屯凹陷的超压强度低于渤海湾盆地其他地区的超压强度。  相似文献   

夏季东海西部表层海水中的pCO₂及海-气界面通量   总被引：10，自引：0，他引：10  

谭燕  张龙军  王凡  胡敦欣 《海洋与湖沼》2004,35(3):239-245

根据2001年夏季长江口及东海西部海域表层海水pCO  相似文献   

波浪作用下海床的有效应力分析   总被引：4，自引：0，他引：4  

吴梦喜  楼志刚 《海洋工程》2002,20(1):64-68

波浪作用下海床的稳定性分析是海洋工程地质评价的重要内容。海床的稳定性可通过计算分析其随时间变化的有效应力场来评估。本文建议了一个周期荷载作用下土体的本构模型 ,并用于计算波浪作用下海床的应力与变形。采用Biot固结理论和有限单元法 ,分析了海床的动态应力场与孔隙水压力场。波浪作用下两种渗透系数时有效应力的动态变化过程结果对比 ,反映了渗透消散作用对海床有效应力变化的影响  相似文献   

基于神经网络的平底结构砰击压力预报   总被引：1，自引：0，他引：1  

陈震  肖熙 《海洋工程》2005,23(2):26-31,41

对利用神经网络预报平底结构入水砰击压力的方法进行了探讨。首先利用仿真软件计算各种情况下平底结构入水所产生的砰击压力，以此形成训练神经网络的数据集。其次利用数据集对三层反馈式网络进行了训练，讨论了不同隐含层节点数对该非线性系统的拟合能力，并且对梯度下降法、动量修正法和基于优化的LM算法的有效性和精度进行了比较，最后得出了适合平底结构入水砰击系统的网络结构。  相似文献   

Plastic buckling of ring-stiffened conical shells under external hydrostatic pressure     

Carl T.F. Ross  Andrew P.F. Little  Kehinde A. Adeniyi 《Ocean Engineering》2005,32(1):753-36

The paper describes experimental tests carried out on three ring-stiffened cones that were tested to destruction under external hydrostatic pressure. The cones were carefully machined from EN1A Steel. All three cones failed by plastic non-symmetric bifurcation buckling in a mode commonly known as general instability. In this mode the entire ring-shell combination buckles bodily.The paper also provides a design chart using the results obtained from these three vessels, together with the results of six other vessels obtained from other tests. The design chart allows the possibility of obtaining a plastic knock down factor, so that the theoretical buckling pressures, based on elastic theory, can be divided by the plastic knockdown factor, to give the predicted buckling pressure. This method can also be used for the design of full-scale vessels.  相似文献