Dedi Apriadi, Rahmat Kurniawan, Syahidus Syuhada
The effects of intermediate and principal stress rotation are commonly ignored when determining soil stress-deformation behavior under two-dimensional or plane-strain conditions. In actual field conditions, soil experiences three-dimensional loading and undergoes stress rotation to reach a stable condition. Therefore, a stress-deformation test that accounts for the effects of intermediate-and principal-stress rotation to capture real soil behavior was conducted. Bandung lacustrine soft clay is formed by the deposition of clay in a giant ancient lake, estimated to have a depth of about 200 m below ground surface. Undisturbed soil samples from this soft clay were taken and investigated in the laboratory by using the Consolidated-Undrained True Triaxial Test. The experiment shows that effective shear strength (ϕ') increases with increasing stress variation (b) up to 10% with an increment of intermediate principal stress 0.5 times the major principal stress. Increasing the principal stress rotation from 0 (zero) degrees to 90 (ninety) degrees decreases undrained shear strength (Su/σc) by up to 15%. The stiffness modulus and the Skempton Af parameter also increase with increasing stress variation. The results obtained from this study are important for evaluating a suitable soil constitutive model for finite-element load-deformation analysis that accounts for anisotropic behavior. © 2019 Association of Geotechnical Societies in Southeast Asia (AGSSEA)-Southeast Asian Geotechnical Society (SEAGS).
Civil Engineering Department, Institut Teknologi Bandung, West Java, Bandung, Indonesia; Department of Civil Engineering, Institut Teknologi Sumatera, South Lampung, Indonesia