Thermal Triaxial Tests to Evaluate Improvement of Soft Marine Clay through Thermal Consolidation

Abstract

Abstract This paper presents an experimental study on the thermomechanical behavior of marine clay from the Santos Basin off the coast of Brazil. The aim of the study is to assess the gain in undrained shear strength of reconstituted, normally consolidated (NC) clay specimens after drained thermal consolidation using a thermal triaxial device. The motivation behind performing these tests is that relatively few studies in the literature have focused on understanding the changes in shear strength of NC clays after a heating-cooling cycle, a path encountered in using heat to improve the properties of soft clays. Furthermore, the high-plasticity marine clays evaluated in this study have a pronounced thermal creep different from that observed in previous non-isothermal tests on clays. Consolidated isotropic undrained triaxial compression tests were performed on specimens consolidated to effective stresses of 100 kPa, 200 kPa, and 400 kPa and then sheared conventionally at room temperature as well as after drained heating-cooling cycles with maximum temperatures of 40°C and 55°C. The results were analyzed according to critical state soil mechanics after drained thermal consolidation, which was well suited to explain the improvement in undrained shear strength. The results have potential implications on the development of techniques that can promote thermal improvement of deep-water offshore anchors installed in soft soil.