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高温、高压作用下不埋或浅埋的海底管线较易发生水平向整体屈曲,土体对管线的阻力决定了管线的变形形态及变形后的应力状态,因此,确定管线受到的土体阻力对准确地分析管线的整体屈曲有重要意义。开展了基于渤海砂性土体的系列室内模型试验,测定了不同埋深条件下管线受到的土体阻力,建立了随埋深条件而变化的土体动态阻力模型,揭示了埋深对土体阻力峰值和最终稳定值的影响。由于ABAQUS内置的罚函数接触模型无法实现管-土界面的动态摩擦特性,开发了子程序VFRIC,在管线温-压联合作用下的整体屈曲分析中成功引入了建立的土体动态阻力模型,实现了土体阻力大小与管线位移相关的动态接触特性模拟,从而较为真实地反映了管线整体屈曲过程中受到的土体阻力变化过程。研究表明,不同土体阻力模型对管线整体屈曲分析结果影响显著,在动态阻力模型中由于土体阻力存在峰值和衰减过程,因此计算得到的管线整体屈曲临界轴力明显提高,管线屈曲变形更为集中,最大弯矩和应变也相应增大。
Under the action of high temperature and high pressure, the submarine pipeline that is not buried or shallow buried tends to buckle horizontally to the whole, and the resistance of the soil to the pipeline determines the deformation of the pipeline and the stress state after the deformation. Therefore, Accurate analysis of the overall pipeline buckling is of great significance. A series of indoor model tests based on the sandy soils of the Bohai Sea are carried out. The resistance of the soil subjected to different depths of the soil is measured. The dynamic resistance model of the soil, which varies with the depth of the soil, is established. Effect of resistance peak and final stability value. Due to the ABAQUS built-in penalty function contact model can not achieve the dynamic friction characteristics of pipe-soil interface, a subroutine VFRIC was developed. The dynamic soil resistance model was successfully introduced in the overall buckling analysis under the combination of pipeline temperature and pressure. The simulation of the dynamic contact characteristics related to the resistance of the soil mass and the displacement of the pipeline reflects the change of the resistance of the soil mass affected by the whole pipeline buckling. The results show that different soil resistance models have a significant impact on the overall pipeline buckling analysis results. In the dynamic resistance model, due to the peak resistance and attenuation of the soil resistance, the calculated critical axial force of the whole pipeline buckling obviously increases, and the pipeline buckling deformation is more Concentration, maximum bending moment and strain also increase accordingly.