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涡激振动会引起海底管跨的疲劳失效,激振频率、固有频率及激振载荷等是其主要影响因素。固有频率是表征结构对荷载敏感程度的指标,管跨共振只可能在漩涡发放主频率接近管土结构的固有频率时才产生。分析了海底土壤力学特性、悬跨长度、管道尺寸、海流速度等对管跨涡激振动的影响规律,结果表明:随着管道覆盖层土壤硬度增大,管跨的最大应力部位逐渐从管跨中点向土壤和管跨的交界区域移动;当海流速度较大时,对于小管径海底管道,靠近管跨中点和管跨两端易发生疲劳失效。在工程设计校核过程中对易引发疲劳失效的部位予以关注,有助于提高海底管道的可靠性。
Vortex induced vibration will lead to fatigue failure of the cross-section of pipelines. Exciting frequency, natural frequency and exciting load are the main influential factors. The natural frequency is an indicator of the structural susceptibility to load. The tube-span resonance may only occur when the main frequency of vortex shedding is close to the natural frequency of the soil-structure. The effects of submarine soil mechanics characteristics, span length, pipe size and current velocity on the vortex-induced vibration of pipe-span are analyzed. The results show that with the increase of soil hardness, the maximum stress of pipe span gradually increases from the pipe span The middle point moves to the boundary between the soil and the pipe span. When the current velocity is high, the fatigue failure is likely to occur in the pipe with small diameter and near the pipe mid-span and both ends of the pipe. During the engineering design check-out, attention should be paid to the parts prone to fatigue failure, which will help to improve the reliability of submarine pipelines.