Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
复制标题
冻融循环下石灰稳定盐渍土岩土特性及微观结构试验研究
DOI：
10.1016/j.coldregions.2019.03.003
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发表时间：
2019-05-01
影响因子：
4.1
通讯作者：
Yuan, Xiaoqing
中科院分区：
文献类型：
--
作者：
Liu, Yaowu;Wang, Qing;Yuan, Xiaoqing
松嫩平原是世界三大苏打盐碱地之一。该地区盐渍土由于其不利的岩土工程性质，无法满足建设工程的需要。本研究评估了在此类土壤中加入石灰的稳定效果。具体而言，它研究了苏打盐碱土的物理化学和力学性质和微观结构是如何被石灰改变的，以及这些变化是如何受到冻融循环和固化时间的影响。结果表明，石灰的加入使盐渍土中的粘土颗粒转化为砂和粉砂颗粒，并导致孔隙尺寸分布（PSD）成为双峰，小孔隙和大孔隙的人口。随着石灰掺量的增加，无侧限抗压强度（UCS）增加，但阳离子交换量（CEC）和塑性指数逐渐下降。冻融循环使粗颗粒破碎，聚集更细的颗粒，增加大孔的直径，降低USC;然而，对含有> 9%石灰的试样的影响可以忽略不计。它进一步表明，土壤的岩土工程性质的变化后立即加入石灰，表明阳离子交换反应发生非常迅速。此外，火山灰反应导致砂大小的颗粒的百分比增加，并在28天的固化后的孔隙率降低。试验结果表明，石灰改良苏打盐碱土的工程性质是可行的。
The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with > 9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.