结构性砂土海床管道上浮破坏的离散元模拟

Investigations on uplift failure of pipe buried in cemented seabed using distinct element method

借助离散单元法（DEM）建立海底管道上浮模型，模拟分析了不同胶结强度下胶结试样的力学特性；通过微观力学响应（局部变形、胶结点破坏分布和位移场）对海底管道上浮破坏机制进行分析；对比分析了海床砂土胶结强度对管道上浮土体破坏的影响（上浮抗力和地表隆起量）。结果表明：伴随土体变形和胶结破坏，上覆土体的渐进破坏主要集中在上覆土体区域内；土表隆起量随着管道上浮位移的增长而增长；胶结强度较高时，管道周围土体无回填行为，上覆土体有拉裂带形成，仅管道附近土体产生胶结破坏，峰值上浮抗力随海床砂土胶结强度的增加有显著提高。

This paper presents a numerical study of the resistance and failure of cemented seabed burying an uplifting pipe using distinct element method （DEM）. The mechanical properties of cemented sand are firstly simulated and analyzed with various inter-grain bond strength; and then, local deformation, distribution of broken bond, and displacement fields are investigated to analyze the failure mechanism of cemented seabed with different bond strength during pipe uplifting; Finally, uplift resistances and upheaval displacement of cemented seabed are discussed with respect to bond strength effect. The results show that the ground deformation and inter-grain bond failure are mainly located in overlying soils of the pipe. Furthermore, The backfilling of soils beneath the pipe vanishes as the increase of bond strength, an apparent tensile-failure rupture above the pipe, and an enhanced uplift resistance of cemented seabed are observed. In addition, the upheaval displacement of seabed increases with the pipe uplift displacement.