Mesoscopic Study on Mechanical and Deformation Behaviors of Reinforced Buried Pipelines under Vertical Loads
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摘要:
为深入研究竖向荷载作用下土工格栅加筋埋地管道的防护效果,基于室内模型试验,建立离散元仿真分析模型,从细观层面探究竖向荷载作用下土工格栅加筋埋地管道与周围土体系统的力学响应与变形行为,揭示不同管道埋深与不同筋材埋深条件下加载板荷载-沉降关系曲线、模型内部颗粒间接触力、颗粒位移与管道垂直径向变形等发展演化规律. 研究结果表明:当管道埋深
H 较浅时(H =0.25D ,D 为管道模型外径),其极限承载力小于管道埋深较大的工况,虽然相同荷载作用下加载板沉降较小,但管道垂直径向变形较大;对管道上方进行土工格栅加筋后,模型系统承载力显著提高,管道垂直径向变形减小;土工格栅埋深越浅,加筋效果越显著,当土工格栅埋深从0.75D 减小至0.25D 时,极限承载力提高约57.2%,管道径向变形减小约27.9%. 本研究从细观层面揭示了管道、土体与土工格栅之间的相互作用机理,实现土工格栅加筋防护埋地管道力学与变形行为的可视化.Abstract:In order to deeply study the protective effect of geogrid-reinforced buried pipelines under vertical load, indoor model tests were carried out, and a discrete element simulation analysis model was established. The mechanical response and deformation behavior of geogrid-reinforced buried pipelines and surrounding soil systems under vertical load were explored from the mesoscopic level, and the development and evolution laws of the load-settlement curve of loading plate, contact force between particles inside the model, particle displacement, and vertical radial deformation of pipelines were revealed under different buried depths of pipelines and reinforcements. The results show that when the buried depth of the pipeline is shallow (
H = 0.25B ), the ultimate bearing capacity is smaller than that of the pipeline with a large buried depth. Although the settlement of the loading plate is smaller under the same load, the vertical radial deformation of the pipeline is large. After the geogrid above the pipeline is reinforced, the ultimate bearing capacity of the model system is significantly increased, and the vertical radial deformation of the pipeline is reduced. A shallower buried depth of the geogrid indicates a more obvious reinforcement effect. When the buried depth of the geogridu is reduced from 0.75B to 0.25B , the ultimate bearing capacity is increased by about 57.2%, and the radial deformation of the pipeline is reduced by about 27.9%. In this study, the interaction mechanism among pipelines, soil, and geogrid is revealed from the mesoscopic level, and the mechanical and deformation behavior of geogrid-reinforced protected buried pipelines were visualized.-
Key words:
- buried pipelines /
- geogrid /
- mechanical behavior /
- deformation characteristics /
- discrete element /
- mesoscopic study
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表 1 离散元模型参数取值
Table 1. Parameter used in discrete element model
名称 接触模型 孔隙率 颗粒相对密度/(kg·m−3) 颗粒直径/mm 摩擦系数 有效模量/MPa 刚度比 平行黏结有效模量/MPa 平行黏结刚度比 黏结激活间隙 平行黏结法向强度/(MPa∙m−1) 平行黏结切向强度/(MPa∙m−1) 砂土 线性接触模型 0.151 2650 1.5~6.0 4.00 20 1 管道 平行黏结接触模型 1500 3.2 0.25 8 2 1900 2 10−5 400.0 400.0 土工格栅 平行黏结接触模型 905 3 0.30 8 1 64.5 1 10−5 24.5 24.5 表 2 离散元数值模拟方案
Table 2. Numerical simulation scheme of discrete element
名称 H l u 未加筋 1.5D/2D/2.5D - - 土工格栅加筋 1.5D 5D 0.25B/0.50B/0.75B -
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