桩承式加筋路堤土拱效应试验研究

桩承式加筋路堤中存在土拱效应,它影响着路堤的荷载传递和沉降变形性状,桩土应力比是反应土拱效应的重要参数。本文通过模型试验,研究了桩土相对位移、路堤高度、桩梁净间距、桩梁宽度及水平加筋体等因素对桩土应力比及路堤沉降的影响。结果表明:①桩土应力比随桩土相对位移的发展而变化,存在上限值和下限值;②路堤高度与桩梁净间距之比越大,桩土应力比越大;桩梁宽度与桩梁净间距之比越大,桩土应力比也越大;③使用水平加筋体能提高桩土应力比,提高的幅度与水平加筋体拉伸强度有关;④当路堤高度与桩梁净间距之比小于1.4时,无论是否使用水平加筋体,路堤顶面均会出现明显的差异沉降;当路堤高度与桩梁净间距之比大于1.6时,路堤顶面不会出现明显的差异沉降。该研究成果可为桩承式加筋路堤设计提供有益的参考。

Experimental investigation on soil arching in piled reinforced embankments

There was significant influence of soil arching on behaviors of piled reinforced embankments.The stress ratio between pile and soil was an important parameter to assess soil arching.Model tests were carried out to investigate the influence of relative displacement between pile and soil,embankment height,width and clear spacing of cap-beam,and geotextile on pile-soil stress ratio and settlements of the embankments.It was shown that: ① Pile-soil stress ratio varied with the relative displacement between pile and soil until some upper and lower bound values.② Higher ratio of embankment height to cap-beam clear spacing as well as higher ratio of cap-beam width to clear spacing would result in higher pile-soil stress ratio.③ The inclusion of geotextile would increase pile-soil stress ratio,the higher the geotextile tensile strength,the higher the stress ratio.④ When the ratio of embankment height to cap-beam clear spacing h/s ≤1.4,apparent differential settlements might occur on the surface of embankment.When h/s ≥1.6,no apparent differential settlements would occur on the surface of embankment.The conclusions drawn from the tests could provide valuable reference for the practice.