甘肃省公路沿线典型地段含盐量对冻胀盐胀特性影响的试验研究

季节冻土区含盐土公路路基在季节性冻胀、盐胀和融沉作用下，发生大量的道路病害，给道路的安全运营带来了严重的隐患。在考察大量现场道路病害的基础上，针对甘肃省季节冻土区公路沿线盐渍化道路病害比较严重的地段，选取几种典型的盐渍土进行室内冻融循环试验来研究它们在周期波动温度条件下冻胀、盐胀和融沉特性，进一步探讨盐渍土地区道路病害产生的机制。试验结果发现，含盐量对路基土冻胀、融沉和盐胀等变形过程有明显的影响，不同的含盐量路基土膨胀机制不同。含盐量较高的土体，变形主要由盐胀引起，没有明显的融沉变形；含盐量较低的路基土，变形主要由冻胀和融沉引起，可能存在盐胀；对于无盐但冻胀敏感性路基土，其变形主要由冻胀和融沉引起。另外，开放系统下盐渍土反复冻融循环后含水率重新分布，含水率普遍增加，且形成了两端含水率高、中间低的现象。

Experimental study of characteristics of frost and salt heaves of saline highway foundation soils in seasonally frozen regions in Gansu Province

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.