关键词: 土力学, 道路工程, 季节冻土, 盐渍土, 冻胀, 融沉, 盐胀

Abstract:

Under the impact of frost heave, thaw settlement and salt heave on the embankment and pavement of the highways in the zones of seasonally frozen ground in Gansu province, Northwestern China, many road damages, which has serious influence on road stability and security, occurred such as pavement cracks and road boiling etc. In this paper, repeated freeze-thaw experiments of saline soils taken from where some damages always occurred in the subgrade and pavement were conducted to investigate the characteristics of frost heave, thaw settlement and salt heave of these saline soils under the periodically fluctuating temperature, and to study the mechanisms of the road damages. The experimental results show that salinity has significant impact on the deformation process; and that the deformation mechanisms are different for the saline soils with different salinity. When salinity is very high, the deformation is mainly caused by salt heave. When salinity is low, the deformation mainly results from frost heave and thaw settlement with possible frost heave. For the non-salt and frost susceptible soil, it is caused by frost heave and thaw settlement. Meanwhile, some suggestions have been proposed to prevent the embankment and pavement of highways from damages and instability in saline soil regions.

Key words: soil mechanics, road engineering, seasonally frozen ground, saline soil, frost heave, thaw settlement, salt heave