用土水特征曲线分析膨胀土的改良效果  

Analysis on Improvement Effect of Expansive Soil by Soil-water Characteristic Curve

作　　者：杨和平[1] 林丽萍[1] 肖杰[1] 湛文涛[1] 

机构地区：[1]长沙理工大学特殊土工程研究所,湖南长沙410004

出　　处：《公路交通科技》2011年第10期1-6,共6页Journal of Highway and Transportation Research and Development

基　　金：国家自然科学基金项目(50978035);交通运输部西部交通建设科技项目(200831800089)

摘　　要：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。For establishing the relationship between the theory of unsaturated soil and engineering problem, the soil-water characteristic curve was used to discuss the improvement effect of expansive soil. Four contents of two improvers, i.e., lime and fly-ash, were added into the Baise expansive soil respectively for free expansion ratio testing. Based on the optimum moisture contents determined by the modified Proctor compaction method, the testing specimens of each improved soil were made. Through dewetting soil-water characteristic curve testing in the range of 5 ~ 1000 KPa conducted by pressure plate apparatus, the expansion properties and soil-water characteristic curve bunch of the improved expansive soils were obtained. The impact of different improvers and mixing contents on the soil-water characteristic curves fitted by VG model were analyzed based on the theory of unsaturated soil and the national determination criterion for expansive soils. It is found that saturated gravity Water content, air entry value, residual water content and curve slope can be used to evaluate the chemical improvement effect on expansive soils. Further analysis shows that the improvement effect can be determined if three of the four indexes of expansive soil have met the requirements. However, saturated gravity water content is indispensable, any two of the rest three indexes could be regarded as other two indexes.

关 键 词：道路工程 非饱和土 土水特征曲线 膨胀土 化学改良 效果评价 

分 类 号：U416.101[交通运输工程—道路与铁道工程]