In order to study the unsaturated characteristics of red clay,Geo-experts self-balanced pressure plate meter and ZJ direct shear apparatus were used in experiments to investigate the soil-water and shear strength characteristics of the typical undisturbed and remolded red clays under different dry densities. Based on the experimental results,the physical and mechanical features of unsaturated red clay were discussed. The results show that mineral composition and micro-structural changes may be the major factors accounting for the difference between physical and mechanical properties of the undisturbed and remolded red clay. The soil-water characteristics curve of undisturbed unsaturated red clay show three stages,which has the obvious air-entry values and residual moisture content,while the soil-water characteristics curve of remodeled unsaturated clay presents a semi-parabolic variation. For the undisturbed red clay,the maximum cohesion occurs in a low moisture condition,and the corresponding moisture content is about 5% to 10% larger than the residual moisture content. Thus,in this case,increasing the number of test groups can optimize the test results. For the remolded red clay,the range of the significantly reduced internal friction angle can be determined according to the plastic limit.%为研究红黏土土体非饱和特性，分别针对典型的原状和重塑红黏土，结合Geo-experts自平衡型压力板仪和ZJ型应变控制式直剪仪开展了不同干密度下土样的非饱和土水特征试验和直剪试验，探讨了红黏土的一些典型非饱和物理力学特征。研究结果表明：矿物赋存状态的改变和微结构的变化是导致红黏土重塑前后物理力学性质发生显著改变的重要因素；原状非饱和红黏土土水曲线呈现典型的三阶段型变化特征，具有较为明显的进气值和残余含水量，而重塑的非饱和红黏土则呈现半抛物线型变化特征；对于原状红黏土来说，非饱和土体黏聚力最大值出现在低含水率状态，对应的含水率比土水曲线的残余含水率高5％～10％。因此，在开展非饱和红黏土抗剪强度试验时，在相应含水率区间处适当增加试验组数可优化试验成果，对于重塑红黏土来说，可根据塑限含水率判断重塑红黏土内摩擦角开始显著减小的区间。
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