Undrained Shear Strength of Soft Soil in Some Areas of Vietnam?s North Central Region

The paper aims to investigate the undrained shear properties of soft soil distributed in some areas of Vietnam's North Central region. To study the undrained shear strength properties of soft soil, different test methods in the laboratory and in - situ at different sites were carried out. In the laboratory tests, the undrained shear strength of soft soil was determined by an undrained unconsolidated compressive test, unconfined compressive test, and consolidated undrained compression test. For the in-situ test, vane shear tests were performed at different depths in the borehole. The experimental results showed that there were various characteristics of undrained shear strength of soft soil in the study area. The undrained shear strength of soft soil depended on many factors, such as liquid limit, dry unit weight, void ratio, and plasticity index. The research results also showed that the correlations between the undrained shear strength of soft soil and physical properties have high determination coefficients.