Applicability of the principle of effective stress in cold regions geotechnical engineering

Abstract

The principle of effective stress is widely recognized as the cornerstone of soil mechanics, with its application extending beyond soils to other porous materials such as rocks and concrete. In recent decades, there has been a significant surge in scientific research and engineering practice in cold regions, where the classical framework of effective stress in soil mechanics is frequently invoked. However, there is no consensus either on mathematical expressions or especially on the physical nature of effective stress in a soil when ice is involved. This paper starts from Terzaghi's principle of effective stress for saturated soils, and subsequently Bishop's work for unsaturated soils and the Clapeyron equation for phase change are introduced as the basis for further discussions. Focus is laid on a comprehensive analysis on formulas for effective stress with respect to cold regions geotechnical engineering. Two categories are classified, in which the effective stress is considered to be undertaken by soil skeleton only and by soil skeleton-ice system together, respectively. They may generate calculated results that can efficiently interpret experiments or observations, while both are rather speculative and faced with major challenges. Controversies on effective stress for unfrozen soils are analyzed with respect to cold regions geotechnical engineering. It is recognized hardly possible to develop a mechanism-based principle of effective stress based on the current understandings, while it is questionable to develop it based on that for unfrozen soils. Two potential approaches are suggested that might be applicable for cold regions geotechnical engineering.