Effect of wave non‐linearity on the standing‐wave‐induced seabed response     

C. P. Tsai  T. L. Lee  J. R. C. Hsu 《国际地质力学数值与分析法杂志》2000,24(11):869-892

A standing wave in front of a seawall may reach a height more than twice of its incident component. When excess pore pressure occurs, it may even induce seabed instability, hence endangering the structure. This issue was studied previously using only linear wave theory. In this paper, standing‐wave theory to a second‐order approximation is applied, in order to demonstrate the differences between these two solutions. The spatial and temporal variations in the instantaneous pore pressure are first calculated, in addition to their vertical distributions. The effects of wave height, water depth and the degree of soil saturation on pore pressure distributions are then discussed, followed by the net pore pressure averaged over one wave cycle. The results suggest the existence of a residual pore pressure in the seabed and its net pore pressure can be used to estimate the wave‐induced liquefaction potential in a soil column. It also indicates that, in deep water, the second‐order solution predicts that a negative pore pressure at an antinode which may be greater than a positive pressure. Overall, the second‐order solution is found to agree better with the experimental results of the pore pressures available, compared to the linear solution. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

直方变差图理论在卫星产品质量检验空间配准中的应用   总被引：3，自引：1，他引：2       下载免费PDF全文

刘瑞霞  师春香  刘杰 《遥感学报》2009,13(2):307-312

将直方变差图中的"驻点"理论引入卫星产品质量验证中,用于解决不同资料对比中的空间配准问题.提出了直方变差图理论用于卫星资料质量检验中驻点、边界点的定义以及应用原理,以中国风云2号C星海面温度产品为例,对这种方法进行了应用试验,结果表明,可以减少卫星产品检验空间配准过程中由于降尺度(downscaling)或升尺度(upscaling)导致像元性质改变而引入的伪误差;通过卫星资料与离散常规观测资料的比对,可以不严格进行空间配准,也可得到相对准确的精度检验结果.  相似文献   

黑龙江双阳河流域土壤-作物-人体系统中硒元素及生态环境与人体健康评价          下载免费PDF全文

梁帅  戴慧敏  刘国栋  翟富荣  刘凯  韩晓萌  宋运红  赵君  张哲寰 《中国地质》2022,49(4):1064-1074

【研究目的】典型黑土地分布区土壤硒自然禀赋、成因来源、生态环境效应及人体健康评价为健康地质研究焦点，开展双阳河流域土壤-作物-人体系统中硒迁移与累积的定量研究，对黑土地富硒农产品开发和地方病防治具有重要意义。【研究方法】测定成土母质、土壤、大气降尘、灌溉水、作物籽实和人发等多介质硒含量，运用GIS、SPSS软件对测试结果统计分析及评价。【研究结果】划定富硒土地46.4 km²，主要沿双阳河及其支流分布；硒以人为成因为主，主要来源于大气降尘补充，输入通量为0.21~1.47 kg/km² · a。土壤、大豆、水稻、玉米和人发硒含量均值为0.305 mg/kg、0.0352 mg/kg、0.0287 mg/kg、0.0198 mg/kg和0.145 mg/kg；作物对土壤硒的富集系数（0.120）远小于1，人发对作物硒的富集系数（4.834）大于1，揭示人发对硒具有较强的浓缩和放大作用，硒在土壤-作物-人体系统中的迁移与积累呈“V”字型模式。【结论】土壤硒含量整体为足硒或富硒，无硒潜在环境风险。大豆、水稻富硒占比为28.4%、9.4%，未发现硒超标情况，无生物硒中毒风险。人发硒含量明显低于参考值0.20~0.60 mg/kg，人体处于缺硒状态，随年龄增长呈递减趋势，可能存在一定的健康风险，应引起地方相关部门关注。创新点：基于系统的生态地球化学数据，运用统计分析学原理，开展典型黑土区土壤-作物-人体系统中硒迁移与积累研究，为富硒农产品开发和地方病防治提供科学依据。  相似文献   

Wave Run-up on A Vertical Seawall Protected by An Offshore Submerged Barrier     

张景新  刘桦 《海洋工程》2009,(3):553-564

Submerged barriers are constructed in coastal zones for shoreline or harbor protection or to prevent the beach erosion. In the present study, the wave run-up on a vertical seawall protected by a submerged barrier is analyzed. The physical configurations include a rigid barrier and a long channel of finite depth. For linear water waves, by matching the velocity along the barrier and along the gap, the systems of linear equations about the velocity potentials are obtained. The wave run-up is further analyzed for various settings of barrier height and distance between the barrier and the wall, i.e. the chamber length. For nonlinear waves and random sea waves, a numerical model is extended to investigate the effect parameters of the barrier on the wave run-up against the seawall. Not only the numerical simulations, but also the analytical results illustrate that the wave run-up on the seawall depends very much on the distance between the barrier and the vertical seawall.  相似文献