By using a triaxial testing apparatus for unsaturated soils, the stress-strain relation and water drainage or absorption during shear were obtained from a series of triaxial tests on unsaturated compacted silt under suction control. By changing the specimen density, triaxial shear tests on unsaturated compacted specimens with different initial void ratios were performed to determine the critical void ratio for indentifying positive or negative dilatancy. By changing the applied suction, triaxial shear tests on compacted specimens at different suctions were performed to determine the critical suction for indentifying water drainage or absorption during shear. Finally, by changing the confining pressure, the stress-strain relation and water drainage or absorption were obtained from the results of triaxial shear tests at different net confining pressures, with the change in water content being almost the same during shear
使用非饱和土三轴试验仪，对击实非饱和粉土进行吸力控制的三轴排气排水剪切试验，得到不同试验条件下剪切时的应力应变关系和吸排水情况.首先，通过改变试样的初始密度，得到不同孔隙比条件下的三轴剪切试验结果，确定非饱和试样发生剪切膨胀和剪切体缩的临界孔隙比约为1.0；其次，通过改变施加吸力的大小，获得不同吸力条件下剪切时的应力应变关系和吸排水情况，并确定试样的临界吸排水吸力值为25～35 kPa；最后，通过改变净围压大小，得到不同净围压情况下的应力应变关系和吸排水情况，其中在剪切过程中不同净围压下的含水量变化大致相同.
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