桩承式路堤中土拱效应产生过程可视化分析

发布时间：2019-06-29 18:58

【摘要】："土拱效应"在提高桩承式路堤承载能力方面发挥着重要的作用。现今关于"土拱效应"的研究主要采用现场原型试验和数值模拟及其在此基础上的理论计算。借助于传统的光弹试验技术,研制出一种直径3 mm、透明度较高的聚碳酸酯光弹颗粒,用于近似模拟桩承式路堤中的土颗粒,通过自制的加载装置和光测力学图像处理系统,实现多种条件下路基内部应力分布的可视化,重点观测模型内部力链网格的产生、分布及变化规律,试验结果表明:填土高度会对土拱的形成及形状产生极大影响,填土高度太小,斜向力链会因缺乏扩展空间无法闭合而不能形成拱结构,随填土高度增加,土拱由三角拱向半圆拱或梯形拱过渡;荷载的大小变化不会影响土拱效应的出现,但会对土拱的结构形状产生较大影响;随桩距比的增大,土拱由三角拱向半圆拱或多拱演化,当桩距比大于3∶1时,土拱效应开始减弱直至消失,路堤承载能力大幅下降。
[Abstract]:Soil arch effect plays an important role in improving the bearing capacity of pile-supported embankment. At present, the research on "soil arch effect" mainly adopts field prototype test and numerical simulation and its theoretical calculation on this basis. With the help of traditional photoelastic test technology, a kind of polycarbonate photoelastic particles with high transparency of 3 mm, in diameter has been developed, which can be used to approximately simulate the soil particles in pile-supported embankment. Through the self-made loading device and photometric image processing system, the visualization of stress distribution in subgrade under various conditions is realized, and the generation, distribution and variation of force chain grid in the model are observed. The test results show that the filling height will have a great influence on the formation and shape of the soil arch, the filling height is too small, and the oblique force chain will not be able to form the arch structure because of the lack of expansion space. With the increase of the filling height, the soil arch will transition from the triangular arch to the semicircular arch or ladder arch. The change of load will not affect the appearance of soil arch effect, but will have a great influence on the structural shape of soil arch. With the increase of pile distance ratio, the soil arch evolves from triangular arch to semicircular arch or multiple arch. When the pile distance ratio is greater than 3: 1, the soil arch effect begins to weaken and disappears, and the bearing capacity of embankment decreases greatly.
【作者单位】：华南理工大学土木与交通学院;华南理工大学亚热带建筑科学国家重点试验室;
【基金】：国家自然科学基金青年基金项目(51208211) 中央高校基本科研业务费专项资金项目(2014ZZ0011) 亚热带建筑科学国家重点实验室自主研究课题(2013ZC18)
【分类号】：U416.12

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