宁明膨胀土持水性研究

Water-retention behaviour of Ningming expansive soil

采用压力板法(吸力范围0~1.5 MPa)及盐溶液蒸气平衡法(吸力范围3~368 MPa)对宁明膨胀土进行了土-水特性试验研究,获得全吸力范围内的土-水特征曲线。采用初始干密度为1.25和1.5 g/cm^3的压实样,比较不同初始干密度对土体持水性的影响;用泥浆制成干密度为1.25 g/cm^3的预固结试样,比较相同干密度下,不同成样方式对土体持水性的影响。结果表明:压实试样初始干密度1.5和1.25 g/cm^3的进气值分别约为70、10 kPa,预固结试样初始干密度1.25 g/cm^3的进气值约为30 kPa;土体质量含水率或者饱和度随着吸力的增加而减小,当吸力大于70 kPa,压实试样两种干密度曲线重合,说明初始干密度对土-水特征曲线影响发生在0~70 kPa,相同吸力条件下,预固结试样持水性更好。

The soil water-holding capacity can be described by soil water characteristic curve（SWCC）,showing the relationship between the suction and the soil water content or the saturation,important in unsaturated soil mechanics.The pressure plate method and vapor equilibrium technique are used to investigate the water retention from Ningming,of Guangxi.The effects of different initial dry density 1.25 and 1.5 g/cm^3 on soil water water retention are compared.Under the same dry density,different sampling methods on the water retention of soil are compared.The test results show that the air entry values of compacted specimens with initial dry density are 1.25 and 1.5 g/cm^3,about 10 and 70 kPa,and the air entry value of pre-consolidatedated specimen with initial dry density 1.25 g/cm^3 is 30 kPa.The water content or saturation decreases with the increase of suction.Under the same suction condition,the water retention of the pre-consolidated sample is better.