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为建立非饱和土理论与工程问题的联系,探讨用土水特征曲线来评价膨胀土的改良效果。将石灰、粉煤灰2种改良剂(均用4种掺量)掺入百色膨胀土,开展自由膨胀率试验,同时按改进葡式击实法确定的各改良土最佳含水率制备试样,通过压力板仪完成脱湿土水特征曲线试验(吸力范围5～1 000 kPa),获得不同改良土的膨胀性及土水特征曲线线系。基于非饱和土理论并参照膨胀土判别的国家标准,采用VG模型进行曲线拟合后,分析不同改良剂及掺量对土水特征曲线的影响,发现可用饱和重力含水率、进气值、残余含水率和曲线斜率4个指标来评价膨胀土的改良效果。进一步的分析研究表明,4个指标中只要3个满足要求就能确定该土已达改性目的,其中饱和重力含水率是必备指标,其余3指标只需满足2个即可。
In order to establish the relationship between unsaturated soil theory and engineering problems, the soil water characteristic curve was used to evaluate the improvement effect of expansive soil. The lime and fly ash two kinds of modifiers (all with four kinds of content) into Baise expansive soil to carry out the test of free expansion, while improving the Portuguese compaction method to determine the best soil moisture content of the modified soil Preparation of the sample , The desiccant soil-water characteristic curve test (suction range 5 ~ 1 000 kPa) was completed by the pressure plate instrument, and the expansibility of different modified soils and soil-water characteristic curve lines were obtained. Based on the unsaturated soil theory and referring to the national standard of expansive soil discrimination, the VG model was used for curve fitting, and the effects of different modifiers and dosage on the soil-water characteristic curve were analyzed. It was found that the saturated gravimetric water content, Moisture content and slope of the curve four indicators to evaluate the improvement effect of expansive soil. Further analysis and research shows that as long as three of the four indicators meet the requirements, it can be determined that the soil has reached the goal of modification. Among them, saturated gravimetric water content is an indispensable indicator, and the remaining three indicators only need to satisfy two.