空气体积率对黏土压实及浸水与冻融稳定性的影响

Effect of volume ratio of air on quality of compaction and stability of soaking and freezing-thawing cycle of clay

采用击实、浸水和循环冻融等系列室内试验,研究了空气体积率Va对黏土压实质量控制、压实黏土的浸水稳定性和冻融循环作用的影响.结果表明:1)相同击实能时,由不同击实类型(重、轻型)所得到的与最大干密度和最优含水率相对应的空气体积率Va不同;相同击实类型时,不同击实能对应于最大干密度时的空气体积率值却基本一样;2)压实黏土的浸水崩解时长随空气体积率的减小而增加,呈现出明显的"3阶段"特征,且不同压实黏土在3个阶段的空气体积率临界值接近;3)整体上压实黏土经历多次冻融循环后的无侧限抗压强度衰减系数Q随空气体积率的增大而减小.提出了寒区黏土堤防填筑的空气体积率应控制在10%以内的建议.

In order to study the effect of volume ratio of air on quality of compaction and stability of soaking and freezing-thawing cycle of clay, a series of tests, including compaction test, soaking test and cyclic freezing and thawing test, are conducted. The test results show that under the same compaction energy, the volume ratios of air corresponding to the maximum dry densities, which are respectively determined by means of heavy and light compactions, are different. Under the same compaction type, the volume ratios of air corresponding to the maximum dry densities are same for the different compaction energy. The duration from the beginning of soaking to destruction for compacted clay demonstrates an increase mode of three-stages with the decrease of volume ratio of air. The critical value of volume ratio of air is close in the three stages for different compacted clays. Repeatedly undergoing freezing-thawing cycles, the attenuation coefficient of unconfined compressive strength for the compacted specimens generally decreases as the volume ratio of air increases. Recommendation has been proposed that volume rate of air should be controlled within 10% for clay embankment filling in cold areas.