Numerical analysis of application for pile-supported reinforced embankment in subgrade widening engineering
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摘要: 为掌握拓宽路堤荷载作用下桩承式加筋路堤的工作特性及其处理效果, 建立了三维有限元分析模型, 采用土水耦合单元模拟地基土, 三维薄膜单元模拟土工格栅, 并基于接触单元考虑桩土界面的状态非线性, 从土拱效应、土工格栅的拉膜效应以及桩土作用等方面验证了桩承式加筋路堤的工作机理。计算结果表明: 土工格栅最大拉力发生在原坡脚位置的桩帽边缘处, 外侧桩帽边缘的格栅应力逐渐减小; 桩承式加筋路堤可使地表不均匀沉降由50.0 cm减小为8.3 cm, 超孔隙水压力由63.7 kPa下降为11.0 kPa, 并避免了老路基顶面出现的反坡现象, 但在老路基处仍出现了较大的地基沉降和超孔隙水压力, 故应充分重视老路边坡位置的地基处理。Abstract: In order to investigate the mechanical behavior and treatment effect of pile-supported reinforced embankment under load in subgrade-widening engineering, a 3D finite element model was established, foundation soil was simulated by using soil-water coupling element, geogrid was simulated by using 3D membrane element, the changing-status non-linearity of pile-soil interface was considered by surface-to-surface contact elements, and the working mechanism of pile-supported reinforced embankment was validated by soil arching effect, tensioned membrane effect of geogrid and pile-soil interaction.Analysis result indicates that the maximum tension in geogrid occurs at the edge of pile cap under the toe of existing slope, and geogrid tension gradually decreases from the edge; pile-supported reinforced embankment can reduce the differential settlement of foundation from 50.0 cm to 8.3 cm, excess pore pressure from 63.7 kPa to 11.0 kPa, and avoid the appearance of reverse slope at the top of old embankment.Meanwhile, there are significant settlement and excess pore pressure at the foundation under the old embankment, so it is important to treat the foundation under the old highway slope.
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图 4 桩帽顶面的桩土不均匀沉降
Figure 4. Differential settlements between pile and soil at the top of pile cap
图 13 老路基顶面的工后变形
Figure 13. Post-con struction settlements at the top of old embank ment
图 14 拓宽路基顶面的工后变形
Figure 14. Post-cons truction settlements at the top of widening embankment
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