Influence of stress history on thermal conductivity of saturated fine-grained soils
Arjun Sivaprasad, Prasenjit Basu
Abstract
This research investigated variations in thermal conductivity k for normally consolidated (NC) and overconsolidated (OC) saturated fine-grained soils at different levels of vertical effective stress. A series of undrained heating tests were performed using a specially designed consolidometer with central radial heating arrangement and temperature measurements within a soil specimen. For different soils investigated in this research, k correlated well with soil consolidation characteristics (compression index λ and swelling index κ) and vertical effective stress σ v ʹ at both NC and OC states. However, the rates of increment of steady- and transient-state values of k ( k st and k tr , respectively) with σ v ′ differed from one soil to another. For OC clays, both k tr and k st increased with preconsolidation stress σ c ′. A set of equations were proposed to estimate both k st and k tr for saturated fine-grained soils as functions of σ v ′, λ, κ, and stress history. At a particular value of σ v ʹ, the dependence of k on overconsolidation ratio (OCR) and σ c ′ marked the importance of considering stress history in the determination of k. The influence of soil mineral composition on k was also explored. Quantification of soil mineralogical composition and available data on mineral thermal conductivity enabled prediction of k tr with reasonable accuracy.