不同制样方法非饱和土的持水特性研究

以一种黏土为研究对象,对其压实样和预固结样进行一系列的持水特性试验和压汞试验,研究了不同制样方法对持水特性和内部孔隙结构分布的影响及在不同各向等应力作用下的持水特性。结果表明:预固结样的内部孔隙分布为单峰孔隙结构,孔隙大小分布较为均匀;压实样则为双峰孔隙结构,但压实样在20 k Pa的竖向压力作用下浸水饱和后,其内部孔隙分布变为单峰孔隙结构。此外,在相同各向等应力条件下初始孔隙比相近的预固结样和压实样的持水特性试验结果表明,预固结样的进气值要比压实样的大,其原因是前者孔隙分布较均匀;其次,受各向等应力越大的预固结样其进气值越大。最后,利用压汞试验的结果对预固结样和压实样的脱湿段的持水曲线进行了推算,并与实测值进行了对比。

Water retention behaviour of soils with different preparations

A series of water retention tests and mercury intrusion porosimetry tests on a clay are performed to investigate the influence of different specimen preparations on water retention behaviour and its pore-size distribution as well as the influence of different isotropic stresses on water retention behaviour. The experimental results show that pre-consolidated specimens exhibit a unimodal pore-size distribution, and unsaturated compacted specimens usually have a double-porosity microstructure, while its microstructure can change due to saturation at the applied pressures of 20 kPa. Under the same initial void ratio and isotropic stress, the pore sizes of pre-consolidated specimens exhibit a uniform distribution, so they have higher air-entry value than the compacted specimens. Under the same initial void ratio of pre-consolidated specimens, the air-entry value increases with the increasing isotropic stress. Finally, based on the results of the mercury intrusion porosimetry tests, a method for predicting the water retention curve of pre-consolidated and compacted specimens during drying is proposed, and the predicted results are compared with the measured values.