稻壳灰改良盐渍土力学特性及抗冻性的研究

在西北季节冻土区广泛分布着盐渍土,其在空间分布上连续性差,工程性质极其不稳定;且浅层盐渍土受冻融作用的反复影响,其力学性质长期处于动态的变化之中,给工程设计与建设带来了极大的挑战.鉴于此,通过压缩试验及无侧限抗压强度试验,研究稻壳灰对盐渍土的改良效果.结果表明,稻壳灰可以显著地改善盐渍土的压缩特性,并提高其无侧限抗压强度,且改良土的压缩系数与抗压强度之间呈现出负相关的线性关系.随着掺灰量和养护龄期的增加,改良土的压缩系数不断减小,无侧限抗压强度呈现出不断增加的趋势,最大可增加4倍左右.以抗压强度损失率为指标对改良土的抗冻性进行了评价,发现改良土的抗冻性随着掺灰量的增加呈现出先增强后减弱的趋势,且在15%的掺灰量时,其抗冻性效果最显著;相对而言,养护龄期对于改良土的抗冻性影响较小.

Experimental study on mechanical properties and freezing resistance of rice husk ash improved saline soil

Saline soil is widely distributed in the seasonal frozen soil area of Northwest China, which has poor continuity in spatial distribution and extremely unstable engineering properties. Moreover, the mechanical properties of shallow saline soil are in dynamic changes for a long time due to the repeated influence of freezing and thawing, which brings great challenges to engineering design and construction. In view of this, through the consolidation compression test and the unconfined compressive strength test, the improvement effect of rice husk ash on chloride saline soil was studied. The results show that rice husk ash can significantly improve the compressive properties of saline soil and increase its unconfined compressive strength, and there is a negative linear relationship between the compression coefficient and compressive strength of improved soil. With the increase of rice husk ash and curing age, the compression coefficient of the improved saline soil continues to decrease, and the unconfined compressive strength shows an increasing trend, which can be increased by about 4 times. By using the loss rate of unconfined compressive strength as evaluation criteria, the frost resistance of the improved soil was evaluated. It was found that the frost resistance of the improved soil increase first and then decrease with the increase of the amount of ash, and the frost resistance effectis the most significant when the amount of ash was 15%. Relatively speaking, the curing age has little effect on the frost resistance of the improved saline soil.