含水率对非饱和砂土力学特性影响的试验研究

Experimental Study of the Influence of Water Content on the Mechanical Characteristics of Unsaturated Sandy Soil

使用 WF 循环单剪试验系统,对不同法向应力、不同含水率的非饱和砂土在单向剪切作用下的力学特性进行了系统的试验研究.砂土含水率为5.4%~25.4%,法向应力为25~300 kPa,主要考察含水率、法向应力对非饱和砂土力学特性的影响规律.试验结果表明：存在一个临界含水率,当非饱和砂土含水率大于该临界含水率时,其剪切应力剪切位移关系将由双曲线函数变为双折线函数.当非饱和砂土含水率小于临界含水率时,非饱和砂土的抗剪强度随含水率增大变化幅度较小.当含水率高于该点后,抗剪强度随含水率增大急剧降低.含水率对土的黏聚力、内摩擦角、剪胀性等力学特性具有重要影响.

The mechanical properties of unsaturated soil under different normal stresses and water con-tents were systematically studied with the cyclic simple shear test,where the water content is 5 .4%~25.4% and the normal stress ranges from 25 kPa to 300 kPa.It mainly investigated the influence of the normal stress and water content on the mechanical properties of unsaturated sandy soil.Experimental re-sults show that there is an equilibrium water content.When water content is greater than the equilibrium water content,the curve of the shear stress and shear displacement of unsaturated sand soil will change from hyperbolic to Double Broken Line model.The shear stress changes in small range when the water content of the unsaturated sand soil is under the equilibrium point.Whereas the shear stress drops sharply as the water content increases .The water content has important influence on the mechanic performance of unsaturated sandy soil,such as cohesion,internal friction,dilatancy and so on.