Experimental analysis of improved bearing capacity in offshore foundations due to thermal consolidation

Abstract

The anchoring of floating platforms is one of many processes in the oil industry that requires innovative strategies. In this respect, there is interest in developing techniques that improve the shear strength of soft soils in order to increase the bearing capacity of offshore foundations anchored in these soils. Normally consolidated clay soil is known to undergo thermal consolidation when submitted to temperature cycles. The present study aimed to assess the impact of a temperature cycle on soft kaolin clay using a reduced-scale physical model submitted to heating at maximum temperatures of 85 °C and 65 °C, followed by cooling. Variables such as pore pressure, temperature at different soil depths and displacement were monitored during the thermal cycle to better understand the phenomenon. The strength profile before and after heating was determined via T-bar tests conducted in different positions in relation to the heat source. The temperature variation increased the undrained shear strength of the soil directly proportional to the temperature applied and inversely proportional to the radial distance from the heat source, reaching improvements of 123%. In this respect, it is believed that applying a temperature cycle to normally consolidated soft clayey soil can improve the pullout capacity of offshore foundations.

Keywords
Offshore foundations; Soft clays; Soil improvement; Physical modeling; Thermal consolidation