Strain rate dependent undrained shear strength response of soft Kandla soil

Department of Civil Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, India

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The extensive coastal stretches of Gujarat are underlain by soft marine clays that are highly plastic, highly compressible, moisture-rich, and sensitive to remolding. These soft clays beneath onshore and offshore infrastructure are exposed to a range of diverse loading rates during their service life, which makes understanding the strain-rate-dependent shear strength behavior of these soils crucial for ensuring the stability and longevity of coastal infrastructure. The present study is focused on evaluating the monotonic undrained response of soft marine clay collected from Kandla Port, Gujarat, India. A series of unconfined compression and consolidated undrained triaxial tests were performed on slurry-consolidated specimens at different strain rates. The high strain rates of loading essentially simulated rapid loading scenarios, such as excavation, surcharge application, and the fast installation of piles and anchors. The experimental findings revealed distinct isotach behavior observed at all axial strain levels, characterized by unique rate-dependent stress-strain curves. An increase in the loading rate was found to reduce the undrained shear strength of the soil, quantified by determining the strength change rate (R). The study further analyzed pore pressure evolution, effective stress path, and maximum obliquity response. The influence of strain rate on the mechanical behavior of soft Kandla soil was also interpreted using strain energy dissipation mechanism.