砂埋管道上浮地基破坏机理的离散元模拟

发布时间：2018-08-06 15:31

【摘要】：本文采用离散单元法(DEM)建立的砂土中管道上浮模型来研究管道上浮时地基的破坏机理。首先考察不同密实度砂土在不同围压下的宏观力学特性,然后通过土体局部变形和颗粒位移场等微观变量分析不同密实度和不同埋深比对管道上浮地基破坏模式和上浮抗力的影响。结果表明:伴随土体变形,上覆土体的渐进破坏主要分布在上覆土体区域和管道周围;松砂中,与应力-应变关系类似,上浮抗力随着上浮位移的增长呈硬化性增长,管道周围土体回填进管道下部形成的空隙中,呈现局部流动破坏模式;密砂中,上浮抗力随着上浮位移的增加先上升后下降,规律与应变软化一致,管道上方先剪切形成倒梯形的上覆土楔,然后管道周围土体回填下部空隙形成流动,呈现先整体剪切破坏后局部流动的破坏模式;随着埋深的增加,上浮抗力增加,密砂中以先整体剪切破坏为主,同时局部流动破坏有明显的趋势。
[Abstract]:This paper uses the discrete element method (DEM) to study the failure mechanism of the foundation when the pipe is floating. Firstly, the macroscopic mechanical properties of the sand under different confining pressure are investigated. Then the different density and the depth ratio of the buried depth are analyzed by the local deformation of the soil and the displacement field of the particle. The results show that the progressive failure of the overlying soil is mainly distributed in the overlying soil area and around the pipeline with the deformation of the soil, which is similar to the stress strain relationship in the loose sand, and the uplift resistance increases with the increase of the floating displacement, and the soil around the pipe is backfilled into the lower part of the pipeline. In the gap, the local flow failure mode is presented. In the dense sand, the uplift resistance rises first and then decreases with the increase of the floating displacement, and the law is consistent with the strain softening. The top of the pipe is first cut into a trapezoid overlying soil wedge, and the soil around the pipe is backfilled to form a flow in the lower space, showing the damage of the local flow after the whole shear failure. With the increase of buried depth, the buoyancy resistance increases, and the shear failure mainly occurs in dense sand, and the local flow failure has an obvious tendency.
【作者单位】：同济大学地下建筑与工程系;同济大学岩土及地下工程教育部重点实验室;同济大学航空航天与力学学院;
【基金】：国家杰出青年基金(51025932) 教育部博士点基金(20100072110048) 国家自然科学基金(10972158)
【分类号】：TU46

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