Tóm tắt:

The objective studied in this article is sand distributed in depth of ten meters to more than 30 meters from the surface. They were located in the underground railway line Nhon - Hanoi Railway Station. In the present study, a series of consolidated drained triaxial tests have been carried out to clarify the shear strength properties of sand. The test results showed that effective cohesion (C’) change from 1 to 6kPa, effective internal fiction angle (’) change from 30026’ to 38010’. The shear strength of these soils influenced by some parameters such as clay content, the relative density and types of soil. Effective cohesion increases by the increment of clay content and effective friction angle increases with increasing relative density (N value); the high values of ' for SW, SW-SM sands. The shear strengths of these soils provide parameters to calculate the stability of underground construction