基于J形铺管法局部屈曲校核及敏感性分析

Local Buckling Check and Sensitivity Analysis Based on J-lay

针对以自然悬链线模型为基础建立的J形铺管局部屈曲失效评价公式的局限性,引入Winkler地基的建模思想对其进行改进,将整个悬跨段分成2段,在接近TDP点附近的大变形段考虑刚度因素,采用大变形梁理论进行分析,在远离TDP点的悬跨段沿用自然悬链线算法,得出了更准确的失效评价公式。通过MATLAB对比计算,验证了分段模型的合理性。对J形铺管局部屈曲的敏感性参数进行对比分析,得到以下结论:(1)分段模型的弯矩连续,弯矩最大位置靠近海床,水深接近铺设最大深度,静水压力大,是容易发生局部屈曲失稳的部位;(2)当其他输入参数不变时,只改变铺设水深和铺设角度,都可以改变校核系数,随水深增加,管道会承受更高的局部屈曲失稳风险,初始缺陷的存在更会降低管道抵抗局部屈曲的能力;在局部屈曲不发生失稳的条件下,应选择大角度铺管;(3)静水压力是对管道局部屈曲失稳影响最大的因素,J形铺管时应优先选用大直径薄壁管,并选取合适的铺管角度以提高管道的抗屈曲能力。研究结果可为J形铺设的安全评估提供理论依据。

In view of the limitation of the local buckling failure evaluation formula of J-lay based on the natural catenary model,the Winkler foundation modeling is introduced for improvement. The entire suspension section is divided into two sections. For the large deformation section close to the TDP point,the stiffness is considered,and the large deformation beam theory is used for analysis. For the suspension section far from the TDP point,the natural catenary algorithm is used. Thus,a more accurate failure evaluation formula is attained which is verified by comparison MATLAB calculation. A comparative analysis on the sensitivity parameters of the local buckling of the J-lay resulted in the following conclusions：（1）The bending moments of the segmented model are continuous. The maximum bending moment position is close to the seabed. The water depth is close to the maximum depth of laying with high hydrostatic pressure.（2） With given input parameters,the laying water depth and laying angle have influences on the checking coefficient. As the water depth increases,the pipeline will bear a higher risk of local buckling instability,and the presence of initial defects will also reduce the pipeline capacity to resist local buckling.The pipeline should be laid at a large angle when the local buckling failure is not a concern.（3） The hydrostatic pressure is the factor that has the greatest effect on the local buckling of pipeline. Large-diameter thin-walled pipeline is preferred for J-lay. Suitable pipe-laying angle should be selected to improve the pipeline buckling capacity.The research results can provide theoretical bases and references for the safety assessment of J-lay.