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回填地基或路基工程中,回填土的压实质量是导致沉降病害的一个重要原因。目前国内通常采用压实度作为填土压实质量控制指标。但压实度自身的准确性受诸多因素影响,若以压实度作为唯一重要指标是存在一定缺陷的。本文通过室内试验研究了不同击实能和含水量下压实黄土的压缩变形规律,分析了压实黄土土样空气体积率的变化规律。研究表明无论击实能如何变化,压实黄土土样的空气体积率在相应击实能对应的最优含水量附近时总是一定的。分析了采用空气体积率作为黄土压实质量附加控制指标的合理性。结合当地工程实际经验,建议在满足规范要求的前提下,以空气体积率不大于6.5%作为判定该地区黄土压实质量合格的参考指标,从而提高当地黄土状填土的压实质量。
In backfill foundations or subgrade projects, the quality of backfill compaction is an important cause of subsidence problems. At present, the compaction degree is usually adopted as the quality control index of earth fill compaction. However, the accuracy of compaction itself is affected by many factors, if the compaction as the only important indicator there is a certain flaw. In this paper, the compression deformation laws of compacted loess at different fracilities and water contents were studied through laboratory experiments, and the variation law of air volume percentage of compacted loess soil samples was analyzed. It has been shown that the air volume fraction of compacted loess samples is always constant near the optimal water content corresponding to the compaction energy, no matter how the compaction can change. The rationality of using air volume rate as additional controlling index of loess compaction quality was analyzed. According to the practical experience of local engineering, it is suggested to improve the compaction quality of loess fill by using the air volume rate of not more than 6.5% as the reference index to determine the compaction quality of loess in this area.