非饱和原状膨胀土平面应变剪切试验性状

Character of undisturbed unsaturated expensive soil under plane-strain test

介绍了非饱和土孔隙压力的测试技术和轴平移技术,利用改装的土工真三轴仪,模拟膨胀土边坡开挖过程的应力状态,对河南南阳原状膨胀土进行了平面应变等应力比卸荷试验,试验中同时测定了土中孔隙压力值,分析了膨胀土中吸力在剪切过程中的变化.试验表明,非饱和土原状膨胀土的吸力状态不仅与土的应力状态有关,还与土体的变形有关,其稳定表现出明显的滞后现象.土体吸力不仅取决于σ1、σ3,还与土中偏应力状态(σ1-σ3)有关.

The testing technique of pore pressure in unsaturated soils and axis parallel translation technique is introduced. The plane strain constant stress ratio-unloading test of undisturbed expansive soils taken from Nanyang, Henan Province, is carried out imitating the stress condition of excavated slope, using the true triaxial apparatus equipment refitted. The pore pressures in sample are measured during the process of sample be sheared. The variation of matric suction in expansive soils is analyzed. The test results indicate that the matric suction in undisturbed unsaturated expansive soils is not only related with soil stress state, but also with soil's strain, suction stabilization in soils is being hysteresis. The suction in soils not only depend on σ_1,σ_3 in soils, but on (σ_1-σ_3)state in soils.