非饱和残积土土-水特性研究及基质吸力估算

残积土在我国南方分布十分广泛,是工程建设及地质灾害评估中主要遇到的土体之一。非饱和状态下,残积土边坡土体的工程性质不仅取决于土的组成、结构和应力状态,还与土中的吸力密切相关;土-水特征曲线表达了土体中含水量与吸力的关系,是非饱和土研究的重要内容之一。选取福建省有典型代表的凝灰质砂砾岩残积土、凝灰岩残积土以及花岗斑岩残积土3种类型土作为试验土样,测定土样完整的脱湿、吸湿循环过程的土-水特征曲线。鉴于基质吸力测量困难,在Barden非饱和土分类方法的基础上,通过分析具有实际工程意义的含水量情况(饱和度介于50%~90%),总结出的利用饱和度预测基质吸力的简易方法具有针对性和实用性。

Soil-Water Characteristics of Unsaturated Residual Soil and Estimation of Matric Suction

Residual soil which widely distributes in south China is one of the major soils encountered in engineering construction and geological disasters evaluation. The engineering properties of residual soil are dependent on the composition, structure, and stress of soil, and also on the matric suction. Soil-water characteristic curve expressing the relationship between soil water content and matric suction is an important part of research on non-saturated soil. In this research we select granite porphyry residual soil, tuff residual soil and conglomerate residual soil, which are typically representative in Fujian province, as test sample soils to determine the soil-water characteristic curve in the process of Dehumidification and moisture absorption. Then we explain lag effects of soil water characteristic curve from the microscopic point of view. Based on Barden’s unsaturated soil classification, we put forward a simple method to predict the matric suction with saturation by analyzing the practical engineering significant moisture (saturation between 50%-90%) in view of the difficulties in measuring matric suction.