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压实黄土作为重要的填筑材料,广泛应用于我国西北、华北公路、铁路、机场等基础设施建设中.由于降雨及蒸发的周期性变化,黄土路基及基础经历着强烈的干湿交替作用.基于此,开展压实黄土风干干燥-滴水增湿条件下的干湿循环试验,利用双线法测试最佳含水量条件下不同初始压实度的黄土土样干湿循环前后的湿陷系数.结果表明:没有经历干湿交替作用的土样,湿陷系数随着压实度的增大而快速减小,当压实度达到90%,提高压实度对于黄土湿陷变形特征的影响较小;5次干湿循环作用后,不同压实度下的试样的湿陷系数均明显增大,且压实度越大,干湿作用对其湿陷变形的影响越显著;压实度K=95%试样在经历5次干湿循环作用后土样上部出现肉眼可见的细微孔隙,体积膨胀,有可溶盐析出,湿陷系数达到0.017,土样出现二次湿陷.
As an important filling material, compacted loess is widely used in infrastructure construction in Northwest China, North China, highways, railways, airports, etc. Due to the periodic changes of rainfall and evaporation, the loess subgrade and foundation undergo intense wet-dry alternation. Based on this, the wet-dry cycle of compacted loess under air-dry-drip-humidifying conditions was carried out, and the collapsibility coefficients of loess samples with different initial compaction degrees before and after wet-dry cycles under the optimal water content were tested by the two-line method. The results show that the collapsibility coefficient decreases rapidly with the increase of compaction degree, and the effect of compaction degree on deformation characteristics of loess collapsible compaction is 90% The collapsibility coefficient of samples under different compaction degrees increased obviously after 5 times of wet-dry cycles. The greater the compaction degree was, the more significant the effect of wet-dry effect on the collapsible deformation was. The degree of compaction K = 95% After 5 times of wet-dry cycle, the sample appeared fine pores visible to the naked eye in the upper part of the soil sample. The volume expanded and soluble salt was precipitated. The collapsibility coefficient reached 0.017 and the soil sample collapsed twice.