大型预制沉箱外海拖航稳性与耐波性分析

Study on Stability and Seakeeping of Large Prefabricated Caisson Towed in Open Sea

大型预制沉箱在复杂海况条件下的拖航安全是其在外海运输过程中需要关注的重点问题。该文利用AQWA构建了拖轮-缆绳-沉箱系统拖带动力学数值模型,并对风浪流作用下,大型沉箱的稳性和耐波性进行了模拟分析。结果表明:沉箱压载后可很好地满足浮游稳定性和大倾角稳性要求;沉箱运动响应受波向影响显著,顺浪与迎浪下纵摇运动剧烈,横向浪下,横摇与垂荡运动剧烈;缆力均值主要取决于流的作用,几乎与波浪无关;随着波高与波周期的增加,沉箱运动幅值和缆力最大值总体上也随之增大。综合考虑运动稳定和目前国内市场上拖轮的性能,建议大型沉箱外海拖航海况限制为四级,浪向角取135°,该值与施工单位的拖航经验值较为接近。该研究结果可为大型沉箱外海拖航方案的确定和作业窗口期的选择提供参考。

The safety of large prefabricated caisson towed under complex sea conditions is a key issue in the process of offshore transportation.The towing dynamics numerical model of tugboat-cable-caisson system is established by AQWA,and the stability and seakeeping of the large caisson under the action of wind-wave-current are analyzed.The results show that the caisson can meet the requirements of towing stability and large inclination stability after ballasting.The motion response of caisson is significantly affected by the wave direction,the pitching motion is significant when following or facing waves,the rolling and heave motion is significant under the lateral waves.The average value of cable force mainly is related to the action of current and almost is independent of wave.With the increase of wave height and wave period,the amplitude of caisson motion and the maximum value of cable force are also increased.Considering the motion stability and the performance of tugboats in domestic market,it is suggested that the towing sea conditions of large caisson should be level 4,and the wave direction angle should be 135°which is close to the towing experience value of the construction company.The results of this paper can provide reference for the determination of towing transportation scheme and the selection of operation window period of large caisson.