Assessing shear strength degradation of gravel-bearing soil from Northeast Forest Region, China, under freeze–thaw action

Abstract

Vehicle-induced disturbances pose significant risks to forest soil integrity. This study investigates the effects of gravel content and freeze–thaw (F-T) cycles on the shear strength of layered forest soils obtained from northeastern China. By analyzing the relationship between the shear strength variations and pore structure evolution of layered forest soils, this study provides critical insights into mitigating environmental challenges and maintaining the stability of such soils. Specifically, 216 remolded forest soil samples obtained from two soil layers were collected and tested and the corresponding findings revealed that changes in gravel content and F-T cycles alter the soil pore structure, consequently influencing soil shear strength. The results also indicated that an increase in the gravel content results in a reduction of soil volume in small pore spaces within the investigated forest soils, while the volume of medium and large pore spaces increases. This leads to gravel particles that gradually dominate the soil framework, causing the soil structure to become loose with an increased porosity. The impact of F-T cycles on the forest soil pore structure was found to be particularly pronounced. Notably, the observed trends found in the current study differ from previous studies on other soil types such as farmland and paddy fields. The results of this study help in refining soil engineering design in forested areas and mitigating the compaction impact resulting from forestry machinery interactions with the soil. Furthermore, the results offer vital data that support assessing geological hazard risks and analyzing soil stability in forested regions.