三种不同管土相互作用模型在触地区立管运动模拟中的比较研究

选择恰当的管土相互作用模型,对于准确描述海洋悬链线立管在触地区的动力响应至关重要。首先总结分析了国内外已有的三类典型管土作用模型,并基于三种模型计算模拟了触地区管道的竖向运动过程,计算结果与试验数据进行了对比验证。选用的三类模型均包括四个管土作用状态,即未接触、初始贯入、上拔和再贯入。研究发现:RQ模型对管道远端管道埋深的预测结果远比试验值小,明显低估了管道的触地区范围;AB模型可以考虑管道的开槽效应,但对于土体强度弱化估算不准,预测的管道埋深远低于试验值;ABY模型能够考虑土体强度的循环弱化,但在模拟管土相互作用时会严重低估土体的强度,预测的管道远端的埋深远大于试验值,这可能导致对管道疲劳寿命的估计错误,需对其进行必要的修正。

Responses of different nonlinear pipe soil interaction models in dynamic cycling of riser in the touchdown zone

It is significantly important to choose a proper pipe-soil interaction model in describing the dynamic response of the marine catenary riser accurately in the touchdown zone. The authors of this paper have analyzed three existing typical models in pipe-soil dynamic interaction simulation at home and abroad, and carried out the simulation of vertical pipe motion in the touchdown zone based on these models in comparison with experimental data. All the three models adopted here include four pipe-soil interaction modes: not in contact, initial penetration, uplift and repenetration. It is found that the pipe penetration in the far end of the pipe predicted by RQ model is obviously smaller than the experimental value, which underestimates the range of the touchdown zone obviously. AB model can consider the trench effect of pipe, but cannot simulate the softening of soil strength accurately, which leads to a much lower penetration prediction than the experimental data. ABY model can consider the cyclic softening of soil strength, but it may underestimate the soil strength seriously in simulating the pipe-soil cyclic interaction and highly overrate the pipe penetration in the far end of the pipe, possibly causing a misestimate of the fatigue life of pipe, which necessarily needs to be modified.