季节冻土区保温法抑制铁路路基冻胀效果研究  

Analysis of the Prevention Effect of Thermal-insulation Method on Frost Heave of Railway Subgrade in Seasonal Frozen Regions

作　　者：许健[1,2,3] 牛富俊[1] 李爱敏[4] 林战举[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室,甘肃兰州730000 [2]西安建筑科技大学土木工程学院,陕西西安710055 [3]西安理工大学水利水电学院,陕西西安710048 [4]菏泽学院资源与环境系,山东菏泽274000

出　　处：《铁道学报》2010年第6期124-131,共8页Journal of the China Railway Society

基　　金：973计划前期研究专项课题(2010CB434813);中科院知识创新工程重要方向项目(KZCX3-SW-351)

摘　　要：模拟气候因素变化过程,得到不同时期冻土路基温度场分布,温度场随时间的变化可以反映出冻结相变区的变化;进一步分析表明,铺设保温板后,对路堤中心下冻结深度线的提升具有显著的作用,但对坡脚附近土体冻结深度线影响甚微,应当做好路基边坡防护工作。考虑土体体积力和土体冻结相变产生的膨胀力,采用热弹塑性冻胀计算模型,得到冻土路基冻胀时的变形和应力分布。在此基础之上,对冻土路基发生最大冻胀时的变形场和应力场进行分析,结果表明:利用保温法增大热阻,推迟或预防地基土的冻结,可明显减小路基冻胀隆起变形,使路基中拉应力(拉应变)减小;铺设保温板后路基坡脚附近天然地表下季节冻结层土体仍发生较大冻胀变形,其冻结时巨大的冻结膨胀力对路堤边坡仍有一定的破坏作用。建议与换填法相结合,改善坡脚附近冻胀敏感性土的土质,减弱其冻胀性,从而减小冻胀力对路堤的破坏作用。By simulating the changing progress of climate features,the thermal regime of subgrade in seasonal frozen regions in each month is got.The variations of the thermal regime with time indicate the variations of the frost soil mass.Further analysis shows that the insulation board can obviously raise the frozen depth level below the center of the embankment with the little effect on that of the soil mass near the slope foot.So the side slope needs to be protected well.Taking into consideration the volumetric force and frozen-heave force of the soil mass and employing the thermo-elasto-plastic model,the author attained the deformation and stress distribution of the frost heave subgrade.The author analyzed the deformation and stress fields of the subgrade with the biggest frost heave deformation.Analysis results show as follows： Frost heave deformation can be obviously decreased by using the thermal-insulation method to increase thermal resistances and prevent the soil freezing,which decreases the tensile stress（tensile strain）;however,the soil mass of the seasonal frozen layer under the natural ground surface near the slope foot is seen in large frost heave deformation and the huge expansion force generated in freezing causes damage to the side slope;the soil-replacing method is suggested to be adopted together with the thermal-insulation method to improve the soil with frost heave sensitive near the slope foot,reduce the frost heave ratio and lessen the damage of the frozen-heave force to the embankment.

关 键 词：季节冻土区 冻土路基 保温法 冻胀变形 温度场 

分 类 号：TU471.7[建筑科学—结构工程] U416.1[建筑科学—土工工程]