路基初始含水率对多年冻土路基水热特征及冻胀变形的影响研究

Study on the Influence of the Initial Water Content of Subgrade on the Hydrothermal Characteristics and Frost Heave Deformation of Permafrost Subgrade

多年冻土路基水热特征与冻胀变形变化规律的研究对于寒区道路冻害成因分析、道路工程设计及冻害治理等方面具有重要意义。本文以青藏公路某典型冻害地段为研究对象,应用含相变冻土路基的水热耦合与冻胀变形理论模型,对周期边界条件下路基初始含水率对多年冻土路基水热特征及冻胀变形的影响规律进行了计算分析。结果表明:在季节性气候变化的条件下,随着路基初始含水量的增加,路基和坡脚位置的多年冻土上界面逐渐上升,路基边界处的冰含量逐渐增加。当路基初始含水率由12%增加到36%时,4月份的路基中心和路肩处冻胀变形量依次增加了17.4mm和20.6mm。此外,路基内初始含水率的变化对路基各边界表面位置冻胀变形的影响程度由大到小依次为路基路肩、路基中心、路基坡脚和天然地表。

The study on the hydrothermal characteristics and the variation law of frost heave deformation of permafrost subgrade is of great significance to the analysis of the causes of road frost damage in cold areas,road engineering design and frost damage control.This paper took a typical freezing-damaged section of Qinghai-Tibet highway as the research object.The theoretical model of water-thermal coupling and frost heaving deformation of phase-change frozen soil subgrade was applied.The influence of the initial water content of subgrade on hydrothermal characteristics and frost heave deformation of the permafrost subgrade under periodic boundary conditions was calculated and analyzed.The results show that under seasonal climate changes,with the increase of initial water content of subgrade,the upper interface of permafrost at the shoulder and the toe of the subgrade gradually increases,and the ice content at the boundary of the subgrade gradually increases.When the initial water content of the subgrade increases from 12%to 36%,the frost heave deformation at the center and shoulder of the subgrade in April increases by 17.4 mm and 20.6 mm,respectively.In addition,the degree of influence of subgrade initial water content change on frost heave deformation of subgrade surface position is from large to small in order of subgrade shoulder,subgrade center,toe of subgrade slope and natural surface.