基于热敏传感技术的破碎波作用下底床切应力测试与研究

The estuarine and coastal evolution is closely linked with sediment movement and the sediment movement directly depends on the shearing stress under the function of flow on the bed surface. The wave breaking area is the most active area with sediment transportation and coastal evolution in the coastal sea area on breaches and wave breaking is the most prominent dynamic characteristic in the wave breaking area. The research has not been mature in the measuring and computing method of shearing stress of seabed under the function of breaking waves so far at home and abroad and there has been no unified computing method for shearing stress of seabed in the wave breaking area formed effectively yet. For the shearing stress of the bed surface under the function of breaking waves has such features as small quantity values and quick change frequency. What is more, there is no valid and feasible measurement manner for a long term influenced by such factors as poor underwater measurement environment and strong turbulent fluctuation of waves. The project is purposed to research spatial and temporal distribution mechanism for shearing stress on the bed surface and sediment movement mechanism under the function of breaking waves through indoor flume experiments, to put forward a calculation method for shearing stress of bed surface under the function of breaking waves and discuss about essential features of sediment suspension movement in the breaking wave area from the angle of shearing stress of bed surface in view of new thermosensitive shearing stress instrument based on micro-nano technology. The expected research results can not only promote the disciplinary development of coastline hydrodynamics but also provide relevant technology references for the intensive study of harbor engineering sediment problems.

河口海岸演变与泥沙运动息息相关，而泥沙运动又直接受制于水流作用于床面切应力的大小。波浪破碎区是海滩近岸区泥沙输移以及海岸演变最活跃的区域，而波浪破碎是破波区内最为显著的动力特征。目前国内外对于破碎波作用下床面切应力的量测计算方法研究尚不成熟，尚未有效形成破波区内底床切应力计算统一方法。由于破碎波作用下床面切应力具有量值较小、变化频率快等特点，加之水下量测环境复杂、水体紊动强烈等因素影响，长期以来一直缺乏有效可行的量测手段。本项目拟借助基于微纳米技术的新型热敏式切应力仪器，通过室内水槽试验研究破碎波作用下床面切应力时空分布机制和泥沙运动机理，提出破波作用下床面切应力计算方法，从床面切应力角度探讨破波区内泥沙悬浮运动基本特征。预期研究成果不仅可以促进海岸动力学学科发展，也可为海港工程泥沙问题深入研究提供相关技术参考。

河口海岸演变与泥沙运动息息相关，而泥沙运动又直接受制于水流作用于床面切应力的大小。波浪破碎区是海岸泥沙输移以及海床演变最活跃的区域，波浪破碎是破波区内最为显著的动力特征。目前国内外对于破碎波作用下床面切应力的量测计算方法研究尚不成熟，尚未有效形成破波区内底床切应力计算方法。由于破碎波作用下床面切应力具有量值较小、变化频率快等特点，加之水下量测环境恶劣、水体紊动强烈等因素影响，长期以来一直缺乏有效可行的量测手段。.本项目拟借助基于微纳米技术的新型热敏式切应力仪器，通过室内水槽试验研究破碎波作用下床面切应力时空分布特征和泥沙运动机理，提出破波作用下床面切应力计算方法，从床面切应力角度来探讨了破波区内泥沙运动基本特征。.利用基于微纳米技术的新型热敏切应力仪，研发智能水体温度控制标定装置，并开展了床面切应力测试与量测试验研究工作。研究结果表明，新型热敏切应力仪响应频率高、稳定性强，量测成果反映了破波作用下床面切应力变化基本规律，解决了热敏切应力仪在河口海岸应用研究中相关参数确定等问题。近岸沿程最大床面切应力均值有向岸增大的趋势，在波浪破碎之前变化趋势较为平缓，而在波浪破碎位置会出现显著的增大，约为破波前的2~3倍。在此基础上，提出了破波作用下最大切应力计算方法。.结合床面切应力量测分析成果，通过泥沙运动水槽试验，研究了破波作用下水动力特性及粉沙质海岸水体挟沙能力、临底含沙浓度和含沙量垂线分布等理论问题，从挟沙水体能量耗散原理出发，提出了水体挟沙能力、近底含沙浓度及含沙量垂线分布计算公式。.本项研究成果丰富了破波作用下床面切应力分布特征和泥沙运动基本规律研究，不仅可以促进海岸动力学学科发展，也可为海岸工程泥沙问题深入研究提供相关技术参考。