DEVELOPMENT OF TFIE METHOD FOR MAINTENANCE OF WATER ROUTE FRONT OF DISCHARGE GATE LINES ON ARIAKE SEA COAST

有明海岸排泄闸门线前水路维护TFIE方法的开发

• 批准号: 13660246
• 负责人: KATO Osamu
• 金额: $ 1.98万
• 依托单位: SAGA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13660246/
• 关键词: Ariake clay; dead weight consolidation; water route; water content; critical erosional rate; jet theory; flash water; screw; 干潟排水; フラッシュ; 限界流速; 排水樋門

Concerning to maintain the water route in front of discharge gate setting at land reclamation, the effective methods are said to remove the mud deposit by flash water, and/or erode by the screw of the fishing boat. Thus, to obtain the basic aspects for developing the water route maintenance system, the field survey for the mechanism of the mud accumulation was carried out, then the experiments were attempted to analyze following items, 1) the erosional and depositional behaviors of fine sediments, 2) the change of critical erosion rate of mud according to dead weight consolidation and 3) the characteristics of the erosional rate by a screw of boatIn the bottom area of Ariake bay, Nanaura tidal land in Saga prefecture, the deposition rate of mud at water route region was measured as about 5cm/day, when the water was not discharged from the gate.The experiment using Ariake clay with sea water in the annular rotating channel elucidated the change of water contents, the cohesion and the critical erosional rate of the clay during 72hr after the dead weight consolidation occurring. In addition, the vertical distribution of water contents ratio was also revealed in mud area. In this experiment, the progress of consolidation by passing time was obviously shown as the change of water content ratio at 10cm depth from the bottom level; 900% at the beginning time subsequently turning to 540% and 300% after 6hr and 72hr, respectively.The flow characteristics caused by rotating of a screw were accountable with the Jet theory, and revealed its action against the bottom. As the axis velocity of flow was decayed with distance from screw -1 powers, the flow rate on the bottom was widen according to Gaussian distribution.The results obtained in this experiment were new and believed to contribute to develop the water route maintenance system.

对于围海造地排水闸前航道的维护，采用闪蒸水清除淤泥存款和/或渔船螺旋桨冲刷是有效的方法。为此，为了获得航道维护体系建设的基本依据，本文对泥沙淤积机理进行了实地调查，并进行了以下几方面的试验研究：（1）细颗粒泥沙的冲淤特性;（2）泥浆的临界冲蚀率随自重固结的变化;在佐贺县七浦滩涂有明湾的底部区域，测得水道区的泥沙沉积速率约为5cm/天，通过有明粘土与海水在环形旋转通道中的实验，阐明了水含量的变化，自重固结后72 h内粘性土的粘聚力和临界侵蚀速率。此外，还揭示了泥质区含水率的垂向分布规律。在本试验中，固结随时间的变化过程明显表现为距底部10 cm处含水率的变化，开始时为900%，6 h后为540%，72 h后为300%，螺杆旋转引起的流动特性符合射流理论，揭示了螺杆对底部的作用。由于水流轴向速度随距螺旋桨功率的增大而衰减，底部流速按高斯分布加宽，实验结果具有一定的创新性，对水路维护系统的研制具有一定的参考价值。