公路改扩建导致新老路基差异沉降的因素分析

基于有限差分原理建立了三维有限元数值计算模型,对公路改扩建中导致新老路基差异沉降的因素进行探讨。结果表明,公路拓宽部分的沉降明显高于老路的沉降,且在新老路结合部位沉降发展最显著。路面的竖向沉降随公路拓宽宽度增加而增加,随新路基弹性模量增加而减小,随新地基土压缩模量增加而减小。其中拓宽宽度和新地基土压缩模量对路基表面沉降影响较大,新路基土弹性模量对路基表面沉降影响较小。这表明新地基土受到的压应力和新地基土压缩模量是影响路面差异沉降的主要因素。工程上可以着重从降低对新地基土的压应力和提高新地基的压缩模量两个角度来降低路面的差异沉降。

Influential factors analysis of the new and old roadbed on the differential settlements due to the highway reconstruction and extension

The paper is inclined to present an analysis of the influence of the road reconstruction and expansion on the differential situations in case of the highway reconstruction and extension.For such a purpose,the paper has established a 3-D finite element numerical calculation model based on the principle of the finite difference. The results of our study show that the settlement of the broadened part of the road turns to be obviously higher than the corresponding value of the original road. The vertical settlement of the pavement has been added up with the increase of the road breadth,whereas decrease with the increase of the compression modulus of the new foundation soil with the increase of the elastic modulus of new subgrade. Among them,the widening breadth and the compression modulus of the new foundation soil may have great impact on the subgrade surface settlement,though the elastic modulus of the new subgrade soil has little effect on the subgrade surface settlement. For it is the compressive stress and compressive modulus of the new foundation soil that may become the main factors that affect the differential settlements of the road surface. From the point of view of the road construction engineering,the differential settlement of the road surface can be reduced by reducing the compressive stress on the new soil foundation and increasing the compressive modulus of the new foundation. What is more,the original road foundation soil can be divided into 2 parts according to the different compaction degree in calculation so as to make the calculation model more consistent with the reality. Therefore,the dominant factors that may lead to the uneven settlement of the subgrade surface ought to be the compressive stress and the degree of compaction of the new foundation,and in turn,the research results of this paper should be able to play a guiding role in the practical engineering practice.