基于水热变化的青藏公路路基纵向裂缝现场测试及成因分析  

The Qinghai-Tibet highway subgrade longitudinal cracks hydrothermal field testing and cause analysis based on moisture and heat changes

作　　者：毛雪松[1] 陈燕琴[1] 樊宇朔[1] 杨锦凤[1] 

机构地区：[1]长安大学特殊地区公路工程教育部重点试验室,陕西西安710064

出　　处：《西安理工大学学报》2014年第3期340-345,共6页Journal of Xi'an University of Technology

基　　金：交通运输部科技基金资助项目(201231879210)

摘　　要：青藏公路现场调查表明,近年来路基纵向裂缝所占路基主要病害比例逐年上升。本文基于青藏公路五道梁段典型断面的温度和水分现场监测结果,分析了不同季节冻土路基温度和水分的空间分布特征,揭示了冻土路基内部温度场、水分场变化的特性:路基内部温度变化滞后于路基表面,并且温度随深度增加呈下降趋势,随大气温度而呈季节性周期变化,温度梯度随深度增加而递减;5月、9月水温分布图表明,受大气降水及地表水重力入渗的影响,加之温度梯度的作用,水分向0℃线集聚明显,致使距路基顶面2m至3.5m范围含水率增大;随着温度降低至0℃以下,未冻水含量集聚减小,2.5m至3.5m以内,含水率急剧下降。研究结果表明,冻土路基内部水热变化是纵向裂缝发生的关键因素,温度的改变引起水分的迁移、冻胀与融沉,冻融循环进一步加剧了纵向裂缝的发育。In recent years,The Qinghai-Tibet highway field investigations shows that the longitudinal cracks in the proportion of the major subgrade diseases are increased year by year. This paper is based on the temperature and moisture testing of Qinghai-Tibet highway five bridge segments typical section to analyse the frozen soil moisture and heat spacial distribution characteristics in the different seasons, and reveal the changing characteristics of the embankment internal temperature field and the water field. The embankment internal Moisture change lags behind the embankment surface, and decrease with increasing depth, and is a seasonal cycle change with the atmospheric temperature, the temperature gradient diminishes with increasing depth ; May and September temperature distribution map shows that moisture to 0 ℃ line concentration is significantly affected by the atmospheric precipitation and surface water gravity infiltration, and com- bined with the effect, whereby to an increase in moisture contents in the range of the 2-3.5 m embankment top surface; As the temperature is reduced to less than 0℃, unfrozen water content concentration decreases, and less than 2.5 m to 3.5 m, the moisture content dropped drastically. The results show that permafrost roadbed internal Moisture and Heat changes is a key factor of longitudinal cracks, heat change leads to moisture migration, frost heave and thawing settlement, freezing and thawing cycle further intensify the longitudinal cracks development.

关 键 词：青藏公路 纵向裂缝 水热变化 现场测试 成因分析 

分 类 号：U416.16[交通运输工程—道路与铁道工程]