Strength Characteristic of Unsaturated Moraine Soil at High-plateau Airport

Triaxial tests were performed on samples of unsaturated moraine soil at a high-plateau airport of China by using the unsaturated soil triaxial apparatus. In the tests, the matric suction and net confining pressure were controlled. In the scheme of the tests, the matric suctions were controlled at 0 kPa, 50 kPa, 100 kPa and 200 kPa. The net confining pressures were controlled at 100 kPa, 200 kPa, 300 kPa and 400 kPa. The results showed that for the unsaturated moraine soil, c' and φ ' increase in the matric suction and their growth rates were similar. The relationship between volumetric strain and net confining pressure showed that the specimens were in a state of dilatancy with a small net confining pressure and the amount of dilatancy rapidly decreased and developed into a shear shrinkage state with an increase in net confining pressure. The last amount of shrinkage was stable at approximately 0.6%. Also, the soil suction characteristic curve for the studied soil was obtained by the tests and the suction stress increased with the matric suction.