基于平面应变试验的非饱和膨胀土强度分析

Analysis of shear strength of unsaturated expensive soil under plane strain test

介绍了非饱和土强度理论的研究现状,总结了FREDLUND提出的吸力内摩擦角Φb的性质与规律研究,根据FREDLUND非饱和土强度理论和吸力内摩擦角Φb的计算方法,利用原状膨胀土的平面应变等应力比卸荷试验,分析得到土样破坏时应力状态下得到的吸力内摩擦角Φb>Φ′,与FREDLUND提出的吸力内摩擦角Φb的变化规律不一致,分析认为,是由于卸荷试验过程导致微裂隙的张开,引起基质吸力的降低,有待于继续深入研究。

The state-of-art of unsaturated soils strength and the angle of internal friction φ^b with matric suction indicated by Fredlund are introduced; and the law of φ^bis analyzed. With the test results of plane strain constant stress ratio-unloading of undisturbed expansive soils, the angle of internal friction φ^bwith matric suction calculated by Fredlund＇s method is great than the effective angle of internal friction φ^b. The result is not accord with Fredlund＇s theory; the reason is that micro- crannies were puffed during unloading test so sa to reduce the matric suction. More experiments analysis must be taken.