摘要
针对软土地基上旧路加宽工程中不可避免的新旧路基间不均匀沉降问题,提出了换填一定厚度的软基并在路堤底部铺一层土工格栅的处理方法。采用有限元法对不加筋不换填、加筋不换填、加筋换填等几种路基加宽的软基处理方案分别进行了计算分析,得到以下结论:(1)换填与加筋相结合可明显降低软基上新旧路堤下地基的不均匀沉降ΔS;(2)当路堤高度和软基厚度一定时,ΔS随换填深度的增加或格栅抗拉模量的增大而减小,因此可以通过选择适当的换填深度和合适的格栅抗拉模量来达到控制不均匀沉降ΔS的目的。如果给定ΔS的容许值,则换填深度与格栅抗拉模量之间存在最佳组合,此时处理费用最低。提出了确定此最佳组合的方法;(3)当路堤高度不变而软基厚度过大时,或软基厚度不变而路堤高度过大时,即使换填深度达到经济最大深度(通常为3 m),不均匀沉降ΔS仍会超过容许值,该处理方法不宜采用。
To control the differential ground settlement between the old and the widened parts of subgrade on soft ground, a method that replacing a certain depth of soft soil with granular soil （such as sand, gravel, etc. ） and placing a layer of geogrid at the base of embankment was proposed. The following measures to improve the soft ground were analyzed by FEM： （1） no improvement; （2） with reinforcement but without replacement; （3） with both reinforcement and replacement. Based on the numerical analysis, the following conclusions were obtained： （ 1 ） The differential ground settlement between the old and the widened parts of subgrade on soft ground, which is referred as AS, can be reduced by a large percent by the third treatment method. （2） For a giving height of the embankment and a certain depth of the soft ground, AS decreases with either the replacement depth or the geogrid tensile modulus increaseing.Therefore, AS can be controlled by giving ＇a proper replacement depth and selecting a geogrid with a desired tensile modulus. When a permissible AS is determined, there is a optimum choice that the magnitude of geogrid tensile modulus and the replacement depth are matched best each other to achieve the leastcost. Thus an optimum choice can be determined by the proposed procedure here. （3） When either the embankment height is constant and the soft layer is deeper than a certain depth or the thickness of soft layer is constant and the embankment is higher than a critical height, △S will exceed the allowable value even if the replacement depth is equal to the maximum of economical magnitude （which is commonly 3 m）, hence this method is improper.
出处
《公路交通科技》
CAS
CSCD
北大核心
2009年第5期35-39,共5页
Journal of Highway and Transportation Research and Development
基金
湖北省交通厅交通科技项目(2005361253)
关键词
道路工程
旧路加宽
加筋与换填
软土地基
road engineering
subgrade widening
reinforcement and replacement
soft ground
作者简介
胡幼常（1962-），男，湖北罗田人，副教授，博士，从事软基处理和加筋土的研究．（huyouchang@163．com）
