Chai Mingtang, Zhang Jianming
State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
Materials (Basel). 2019 Apr 1;12(7):1068. doi: 10.3390/ma12071068.
The warm and ice-rich frozen soil (WIRFS) that underlies roadway embankments in permafrost regions exhibit large compression and thaw deformation, which can trigger a series of distresses. Cement and additives were used in this study to improve the compressibility and thaw-settlement properties of WIRFS. We, therefore, selected optimum additives and studied the improvement effect on the frozen soil with 30% water content based on our previous research. Given constant load and variable temperatures, compression coefficients, thaw strains, and water content changes were obtained at temperatures of -1.0 °C, -0.5 °C, and 2.0 °C to evaluate the effect of improvements. A scanning electron microscope (SEM) was then used to observe the microstructure of improved soils and analyze causal mechanisms. Data show that hydration reactions, physical absorptions, cement, and additives formed new structures and changed the phase of water in frozen soil after curing at -1.0 °C for 28 days. This new structure, cemented with soil particles, unfrozen water, and ice, filled in the voids of frozen soil and effectively decreased the WIRFS compression coefficient and thaw strain.
多年冻土地区道路路堤下伏的富含冰的温暖冻土（WIRFS）表现出较大的压缩和融化变形，这可能引发一系列病害。本研究使用水泥和添加剂来改善WIRFS的压缩性和融沉特性。因此，基于我们之前的研究，我们选择了最佳添加剂，并研究了其对含水量为30%的冻土的改良效果。在恒定荷载和变温条件下，分别在-1.0℃、-0.5℃和2.0℃温度下获得压缩系数、融化应变和含水量变化，以评估改良效果。然后使用扫描电子显微镜（SEM）观察改良后土的微观结构并分析其成因机制。数据表明，在-1.0℃养护28天后，水化反应、物理吸附、水泥和添加剂形成了新结构并改变了冻土中的水相。这种与土颗粒、未冻水和冰胶结在一起的新结构填充了冻土孔隙，有效降低了WIRFS的压缩系数和融化应变。
