长春地区公路路基土冻胀敏感性因素分析

Impacted factors of frost heaving susceptibility in roadbed soil in Changchun Regions

以吉林省内3条干线公路路基土为研究对象,研究土(粒度成分、矿物成分、盐分,尤其是微观结构、土体密度)、水分、温度及荷载对冻胀的影响。通过室内物理化学试验、冻胀试验、SEM图片测试分析及野外长期观测,获得大量数据。分析表明:路基土具备冻胀的优势条件;亲水性强的黏土矿物含量越高未冻水含量越少,不利于冻胀;土体起始冻胀含水率随压实度增大而减小,压实度相同时,粉质黏土起始冻胀含水率大于黏土;压实度对冻胀影响有一个敏感值,研究区此值为95%;0～-5℃是产生水分迁移的主要温度;研究区路基土具团聚结构,单元体排列不定向,颗粒之间微孔隙发育,为毛细水上升提供有利通道,也为结合水提供赋存空间;以上结果为长春地区道路冻害防治提供理论依据。

There are three groups of subsoil as objects which come from zones of Changchun. By studying frost heaving susceptibility factors including soils （granularity and mineral component, salt content, density, and microstructure of soils . The last one was especially emphasized）, moisture in soils , freezing temperature and load over the soils. Many tests were done in labs to get physical and chemical property indexs, frost heaving tests, SEM tests and field tests, and we get a lot of datum. By analyzing the datum, we got some conclusions ： the soils are easy to frost heave in research zone. It is disadvantage for frost heave when there are a lot of clay minerals in the soils which have strong hydrophilicity. With the density of the soils increasing, intial freezing moisture is descending. When density is same, intial freezing mois- ture of silty clay was higher than clay＇s. There was a sensitive value of compaction of subsoil, this value was about 95℃in research zone. Water in soils was easy to migrate during 0-5℃. By analysis of soil microstructure, we found that the soits have agglomerated structure, the units of structure in the soils are not directional, and micro pores are abundant, thus provide favorable channels for capillary water to moveand offer space for film water storing. According to the results, some theoretical basis will be offered for frost damage preventing and curing in roadbed in seasonal frost zones.