区域尺度灾害性海浪的非静压荷载分析和风险分布评价的模型方法研究

The nearshore wave is a dominant hydrodynamic impact for the failure of coastal structures during extreme marine events. As the modern computing power became more available to researchers, the numerical modelling has become a sophisticated tool for an accurate and effective assessment of the wave load and risk distribution for the probable affected area. However, the neglect of nonlinear terms, unsteady radiation stresses in standard large-scale phase-averaged wave and surge models results in underestimation of maximum wave heights and current velocities in the near-coast region, and the inaccuracy of regional-scale risk assessment. The small-scale full Navier-Stokes modelling of the wave-structure interaction heavily rely on the regional-scale computed results as well. Currently there are criteria for surge and wave loads that are used for design. However, standard empirical loads neglect the effects of unsteady wave and surge processes, which can lead to much larger loads in the immediate vicinity of the shoreline..The long-term goals of this project are developing systems for regional-scale assessment of the wave load and risk distribution in near-coast areas during extreme marine events: 1) Develop a GPU based 3D nonhydrostatic phase-resolving rotational hydrodynamic model which is expect to excel in the highly dispersive nonlinear wave modelling in coastal ocean with an original breakthrough in resolving depth-varying pressure and velocities. The model is able to accurately predict highly dispersive nonlinear wave breaking, shoaling, and breaking for complex hydrodynamic conditions. 2) Simulate selected regional-scale study areas in China, United States, and Philippines devastated by hurricane storms with detailed flow thickness, orbital velocities, and wave forces computed. The hydrodynamic load distribution is computed and compared to the damage state distribution from the field survey conducted after the storm. 3) Carry out preliminary examinations of the relationship between single variables and damage and backward multiple regressions using many variables. The wave load and the damage state distribution are correlated with a proportional expectation. The weight analysis of velocities, wave heights, and relative shielding are carried out. The regional-scale assessment method of the wave risk are derived and parameterized based on this study. .Present research would contribute significantly to the further exploration of the rotational phase-resolving hydrodynamics theory and the wave disaster mechanism. This assessment system would be extremely useful to engineers and planners to design coastal communities that will withstand future marine hazards.

灾害性海浪的直接冲击是近海近岸结构物、设施破坏的主要动力因素。本研究旨在建立区域尺度灾害性海浪的非静压动力荷载分析模型和风险分布评价方法：1开发基于GPU计算的三维非静压相位解析有旋水动力数模，弥补相位平均类模型的线性特征和忽略辐射应力所造成的海浪荷载极值计算的严重低估；在解析非静态压力和有旋流上进行理论创新，运用坐标分离的多项式数值迭代精简矩阵维度，大幅提高相位解析模型的计算效率和精度。2模拟重现我国海南省、美国和菲律宾沿海台风浪过程，计算非静压海浪荷载时空分布并深入分析作用机理，与结构物破坏的调查数据对比验证，利用回归分析法构建区域海浪荷载与结构物破坏程度的相关性，量化各影响要素如流速、浪高、结构物特征等的风险权重，推导基于多影响要素的区域海浪风险参数化定量评价方法。为非静压相位解析有旋水动力理论和海浪灾害机理的科学探索提供原创性基础。为沿海区域规划、工程设计、防灾减灾等提供科学参考。

本项研究按照申请书和计划书执行，完成了预期研究目标。研究针对海岸地区非线性、高频散的复杂浪、流水动力环境，开发基于GPU并行算法编译的高阶非静压相位解析水动力模型，结合海岸房屋脆弱性预判方程，为灾害风险精准预判建立了方法体系。应用所开发模型模拟重现了：美国新泽西Staten Island、Long Island在飓风Sandy期间、菲律宾东部海岸Hernani在台风海燕期间的台风浪过程。计算非静压海浪荷载时空分布并深入分析作用机理，与结构物破坏的调查数据对比验证，利用回归分析法构建区域海浪荷载与结构物破坏程度的相关性，推导基于多影响要素的区域海浪风险参数化定量评价方法；基于巨石受水动力作用向岸迁移的距离调查数据，开展了水动力受力分析及巨石运动机理研究，建立了块体受水动力作用的运动模型，构建了台风狼波高与迁移距离的相关性，研究成果可为远古风暴强度推算提供方法。研究结果显示，该模型融合了统Boussinesq近似量纲和Green-Naghdi的加权积分结构，有效规避了无旋假设，建立了波浪破碎、数值造波方法，可快速模拟高度弥散状态下海浪的变形、破碎、浅变等非线性现象，弥补相位平均类模型的线性特征和忽略辐射应力所造成的海浪荷载极值计算的严重低估，提高了海浪非静压荷载的精度。