冻结过程中水分盐分结晶相变对盐渍土压力的影响

冻胀和盐胀导致土体变形破坏对建筑基础、公路铁路路基等构成严重威胁。本文开展了冻结过程中水分盐分结晶相变对盐渍土压力的影响试验研究,结果表明:冰晶压力随着含水率的增加而增大;在一定干密度和含水率下,盐结晶压力随着含盐量的增大而增大。冻结过程中,土压力首先保持不变,然后迅速增大,最后迅速降低至稳定。冰晶压力与盐结晶压力作为张应力作用在孔隙壁上使得土颗粒间相互挤压,达到峰值应力后,土体结构破坏和土颗粒重分布导致土压力迅速降低至稳定。此外,还讨论了传统盐结晶压力方程和冰晶压力方程的适用性,最后对冰晶压力方程进行了修正。

Effects of Water and Salt Crystallization Phase Change on Saline Soil Pressure During Freezing Process

Soil deformation caused by frost heave and salt heave is a serious threat to building foundations, roads and railway subgrades. The effects of water and salt crystallization phase change on saline soil pressure during freezing process were studied experimentally. The results show that the ice crystallization pressure increases with the increase of moisture content, while salt crystallization pressure increases with the increase of salt content under a certain dry density and moisture content. During the freezing process, the soil pressure unchanges firstly, then increases rapidly, and finally decreases to stability. The analysis shows that the ice crystallization pressure and salt crystallization pressure act as tensile stress on the pore wall to squeeze the soil particles between each other, after the peak stress, the breaken of soil structure and redistribution of soil particles lead to the soil pressure rapidly decreases to stability. In addition, the applicability of the traditional salt crystallization pressure equation and ice crystallization pressure equation were discussed. Finally, the ice crystallization pressure equation was modified.