青藏铁路冻土路基活动层形成特性研究

在环境温度季节性变化的条件下进行室内模拟试验,探索了模拟冻土路基活动层形成的试验方法,研究了青藏高原多年冻土区路基活动层的形成活动规律。试验表明：活动层从初始形成到基本稳定过程中,近地表土层对外界温度场的变化响应灵敏,随外界温度的改变出现规律的波动；深层土层对外界温度的变化表现出滞后性,温度曲线波动幅度较小；活动层在趋于稳定的过程中土层的温度特征呈现出较为明显的区域相似性,在一定外温影响范围内土层温度场变化规律接近；在环境负温的初期表层土层迅速降温,活动层厚度开始逐渐减小,受外界气温及深层冻土冷源作用的共同影响,活动层冻结过程中会出现从上下边界同时冻结的现象,加快了活动层的冻结速度。

Experimental Research on Indoor Activity Layer Formation

The experimental model was constructed in the high and low temperature alternating temperature box. The initial moisture content of the subgrade fill, the constant of the model structure, the indoor temperature test as the variable, the experiment method of the active layer formation of the simulated frozen soil subgrade was explored. The formation of the active layer in the Qinghai-Tibet Plateau permafrost transitional section of the roadbed activity law. The results show that the active layer from the initial formation to the basic stability of the process, the near surface soil to the change of external temperature sensitive response, with the outside temperature changes the pattern of fluctuation; deep soil changes on the outside temperature lags behind, the temperature curve of volatility is small; the temperature characteristic of active layer in the process tends to be stable in the soil showed obvious regional similarity in close to the outer temperature within the scope of influence of the soil temperature field variation; rapid cooling in the early stage of the surface soil environment of negative temperature, active layer thickness reduces gradually affected by ambient temperature and cold source of deep frozen soil, emerged from the upper and lower boundary while freezing the phenomenon of active layer in the process of freezing, accelerate the freezing rate of the active layer.