干密度和竖向应力对原状非饱和黄土土水特征影响的试验研究

EXPERIMENTAL RESEARCH ON INFLUENCES OF DRY DENSITY AND VERTICAL STRESS ON SOIL-WATER CHARACTERISTIC CURVES OF INTACT UNSATURATED LOESS

利用非饱和土固结仪对原状非饱和黄土进行常含水率固结试验,试验中分别选用3种不同干密度、6种不同含水率试样,分析天然干密度和竖向应力对原状非饱和黄土土水特征的影响。试验表明,原状非饱和黄土的吸力随着试样含水率的增大而降低,干密度对土水特征曲线有不可忽视的影响。同一含水率下,原状非饱和黄土的吸力随着天然干密度的增大而增大;提出吸力临界荷载的概念,干密度相同时,吸力临界荷载随着含水率的增大而降低;含水率相同时,吸力临界荷载随着干密度的增大而增大。含水率一定时,竖向荷载引起的干密度变化与初始干密度变化对吸力的影响是不相同的;竖向应力对土水特征曲线影响较小,可以用无荷载条件下的土水特征曲线来描述其吸力状态。最后,提出原状非饱和黄土土水特征曲线函数经验表达式。

Experimental research on intact unsaturated loess under three different natural dry densities and six different water contents is conducted by using unsaturated soil consolidation apparatus,and the effects of natural dry density and vertical stress on soil-water characteristics are analyzed. The test results show that the initial matric suction of the intact unsaturated loess water content,and the dry density has an considerable effect on soil-water characteristics. A concept of critical load of suction is proposed. Under the same dry density of the intact unsaturated loess,the critical load of suction decreases with the increasing water content. Under the same water content of the intact unsaturated loess,the critical load of suction increases with the increasing natural dry density. Under the fixed water content,the change of dry density induced by the vertical load has different effects on the suction from the change of the initial dry density. The vertical stress has little effect on soil-water characteristic curves,so the suction situation could be described by using soil-water characteristic curves under zero-load condition. Finally,the function of fitted soil-water characteristic curves is established.