Hydro- and Soil- mechanical Study on Coastal Structure Damage due to Wave Motion and its Prevention

波浪运动引起的海岸结构破坏的水土力学研究及其防治

• 批准号: 12450202
• 负责人: NAGO Hiroshi
• 金额: $ 9.6万
• 依托单位: OKAYAMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450202/
• 关键词: Water Wave; Sea Bed; Liquefaction; Centrifuge Wave Test; Bank Protection; Riprap; Discontinuous Deformation Analysis; Distinct Element Method; 進行性液状化; ポストリクイファクション

So many damages of coastal structures due to storm waves are reported every year. We considered that such failures of structure are mainly caused by the liquefaction of sea bed around the structure. In this research we treated such dynamical problem as the interaction problem of soil and water. The following results are obtained in this research.1. The processes of progressive liquefaction, densification and re-liquefaction of loosely deposited sand bed under oscillating water pressure were clarified experimentally and theoretically for one-dimensional model. In the theoretical treatment the elasto-plastic model was adopted.2. The centrifuge wave test with dynamical similarity was carried out. The liquefaction and densification process of sea bed were reproduced in the experiment. These processes were explained theoretically by two-dimensional elasto-plastic model. Further more, the dynamic behavior of sand and rock around the rubble mound breakwater were observed in this experiment.3. The lift up of liquefied sand and the movement in the water were simulated numerically by the coupling of manifold method and discontinuous deformation analysis.4. The effect of pore water pressure in the sand bed on the sediment transport was investigated. The increase of the sediment transport was explained by the numerical movable bed model.5. The flow of back filling sand behind vertical sea wall was treated experimentally. The qualitative characteristics of flow were related to the water pressure variation and properties of material.6. The validity of the counter measure to prevent the flow of back filling sand was shown by the field test.7. Three-dimensional numerical model to analyze the movement of block in the liquefied sand layer was developed.8. The local scour around bridge pier under the co-existence of wave and current is experimented. It is found that the amount of maximum scour depth becomes larger than the scour depth under the steady flow condition.

风暴潮对海岸结构物的破坏每年都有大量的报道。认为结构物的破坏主要是由于结构物周围海床的液化引起的。本研究将土与水的相互作用问题作为动力学问题处理。本研究取得了以下成果：1.通过一维模型试验和理论分析，阐明了松散沉积砂床在振荡水压力作用下的液化、密实化和再液化过程。理论处理中采用弹塑性模型。2.进行了动力相似离心波浪试验。实验再现了海床液化和密实化的过程。用二维弹塑性模型对这些过程进行了理论解释。此外，本文还对斜坡堤周围砂、岩的动力特性进行了试验研究.采用流形元法和非连续变形分析相耦合的方法，对液化砂土的上提和在水中的运动进行了数值模拟.研究了砂床孔隙水压力对泥沙输移的影响。动床数值模型解释了输沙量的增加。5.对直立海堤后回填砂的流动进行了实验研究。流动的定性特征与水压力的变化和物料的性质有关.通过现场试验，验证了防止回填砂流的措施的有效性.建立了液化砂层中块体运动的三维数值模型.对波流共同作用下桥墩周围的局部冲刷进行了试验研究。结果表明，在恒定流条件下，最大冲刷深度大于冲刷深度。