Research of undrained shear strength of soft clay in the Lo Voi residential area, ward 1, Tuy Hoa city, Phu Yen province by unconfined compressive strength and direct simple shear test
Abstract
The undrained shear strength of soft clays is an important parameter for designing embankments, shallow foundations, and pile foundations. The undrained shear strength of soil is determined from laboratory tests (i.e., triaxial test, direct shear test, unconfined compressive test) and field tests (i.e., CPT tests, vane shear test). In this study, the author used intact clay samples with a 90 mm diameter collected in the Lo Voi residential area, ward 1, Tuy Hoa city, Phu Yen province. The main purpose of this study is to use the unconfined compressive test and direct shear test to investigate the shear strength value of samples. Then, the values of undrained shear strength (S u ) from the unconfined compressive strength test were compared with the values of shear stress (τ) from the simple shear test. The results show that the undrained shear strength of the samples obtained from the unconfined compressive test and the direct shear test are both less than 25kN/m2 and the percentage difference is obtained from both testing methods about 1.2%. The soft clays in the survey area are classified as soft and very soft. Therefore, buildings are built on this clay foundation with a relatively large distribution thickness, so it is necessary to treat the soft soil.