椭圆形悬浮隧道管节沉放过程的波激运动特性分析

Wave-Induced Motion Characteristics of Elliptical Submerged Floating Tunnel Tube During Sinking

为了理清悬浮隧道施工过程中波浪参数与沉放体系中管节运动规律、系泊锚索张力的关系,以沉放过程中的大尺度椭圆形悬浮隧道管节为研究对象,基于ANSYS-AQWA软件采用数值模拟方法分析管节在规则波作用下的波激特性。在通过已有悬浮隧道管节的缩尺模型试验验证本文所用数值方法正确性的基础上,研究波浪环境中大尺度椭圆形悬浮隧道管节运动的时程历程曲线、RAO曲线以及锚索支撑的索力分布规律,得到沉放系统时域、频域运动特性与波浪参数(周期、波高、入射角)及管节的沉没深度、浮重比(BWR)之间的变化关系。结果表明:1)波高、周期增大时,管节位移与缆绳缆力均显著增加,增至一定程度时管节位移出现非线性特征,锚索出现松弛现象。2)在入射角增大的过程中,垂荡RAO曲线图分布规律基本一致,横摇值增大,纵摇值减小。3)不同沉没深度时横荡RAO曲线规律一致;垂荡RAO曲线对沉没深度非常敏感,其增加时垂荡值减小;沉没深度越大,横摇RAO值越小。4)管节浮重比减小时,管节横荡位移幅值减小,变为周期运动或准周期运动,缆索索力均大于零,松弛现象消失,索力时间历程呈现准周期规律。

To investigate the relationship between wave parameters and the motion law of tube,as well as the tension of mooring cables,in the sinking system during the construction process of the submerged floating tunnel(SFT),the waveinduced characteristics of a large-scale elliptical SFT tube under regular wave action are analyzed using the numerical simulation methods based on the ANSYS-AQWA software.The feasibility of the proposed numerical method is validated using a scale-model experiment of SFT tube,and the time-history curves,the response-amplitude-operator(RAO)curves,and cable force distribution patterns of the large-scale elliptical SFT tube in wave environment are examined.The variation relationships between the time/frequency-domain motion characteristics of the sinking system and wave parameters including the period,wave height,incidence angle,as well as the sinking depth and buoyancyweight-ratio(BWR)of the tube,are obtained.The results reveal the following:(1)Both the tube displacements and the cable forces increase significantly as the wave height and period increase,when they grow to a certain degree,the tube displacements exhibit nonlinear characteristics and the anchor cables show slack.(2)During the process of increasing the incident angle,the distribution pattern of the heave RAO curve is basically consistent,with an increase in roll value and a decrease in pitch value.(3)The sway RAO curve pattern is consistent at different sinking depths.The heave RAO curve is very sensitive to the sinking depth, and as it increases, the heave value decreases. When the sinking depth is greater, the roll value is smaller. (4) When the BWR of tube decreases, the amplitude of the transverse displacement of tube decreases and becomes periodic or quasi-periodic motion. The cable tension is greater than zero, the slack phenomenon disappears, and the time history of the cable tension shows a quasi-periodic pattern.