中文摘要：

压实的路基填土一般处于非饱和状态。然而目前路基设计方法一般是基于经典的饱和土理论,没有反映出路基土的本质。为了模拟路基边坡的慢速失稳破坏,进行了不同围压下控制吸力的固结排水三轴试验,研究了非饱和路基粘土的强度与变形特性。结果表明：非饱和路基粘土的应力~应变曲线均有明显的峰值,变形模量和偏应力峰值均随吸力的增加而增大,峰值过后呈现出明显的应变软化现象;相同吸力下,围压越大,偏应力峰值越高;不同吸力下,随着吸力的增加,表观粘聚力逐渐增大,但是这种增大关系是非线性的,而有效内摩擦角有所减小,但变化不大;非饱和路基粘土试样在剪切过程中一般表现为剪缩。

英文摘要：

The compacted subgrade is often in an unsaturated condition,but the current design method of subgrade is based on the classical saturated soil theory,which could not reflect the nature property of subgrade soil.In order to simulate the slow failure conditions of subgrade slope encountered in the field, the triaxial consolidated-drained（CD） tests under different confined pressures are conducted by controlling the sample suction to explore the strength and deformation characteristics of a clay subgrade.The test results show that the strain～stress curves of unsaturated subgrade clay have the distinct peak value,the modulus of deformation and the peak value of deviator stress increase with the increment of suction,and the curves appear in the obvious strain softening.Under the same suction,the greater the confined pressure,the higher the peak value of deviator stress,and under the different suction conditions,the cohesion gradually increases with the increment of suction,but the relationship between cohesion and suction is not linear.At the same time,the effective angle of internal friction only reduces a little.The bulk deformation characteristics of samples are commonly shrinking during shear process.