Abstract
Estimation of the residual strength of the soil on the landslide sliding surface is essential for analyzing reactivated landslides. This study investigated the influence of over-consolidation ratio (OCR) and shear rate on the residual strength of SM-type (silty sand) landslide soils in the Three Gorge Reservoir using ring shear tests under drained conditions. A series of ring shear tests were conducted to measure the drained residual strength under over-consolidation ratios of 1–12 and shear rates of 0.06–30.00 mm/min. Test results showed that residual strengths of SM-type landslide soils were not affected significantly by the over-consolidation process. The effect of shear rate on residual strength did not exhibit a regular pattern at shear rates of 0.06–10.00 mm/min, and behaved negatively at a high shear rate of 30 mm/min. The reduction in residual strength at higher shear rates may be attributable to increases in the water content of the shear zone and the amount of finer particles, due to particle breakage and/or larger grains being pushed from the shear zone.
Highlights
The residual strengths of landslide soils in undrained and drained conditions have been investigated widely in recent years
Residual strength increased with increasing overconsolidation ratios (OCRs) for Pepper shale and Cucaracha shale[10].The residual strength of natural soils was independent of stress history and the initial soil condition was not significant influence on residual strength[11]
Three types of variation of residual strength occur with increasing shear rate: (1) a positive rate effect—an increase in residual strength when sheared at higher speeds; (2) a negative rate effect—a decrease in residual strength with increasing shearing rate; and (3) a neutral rate effect—a constant residual strength irrespective of shearing rate[19]
Summary
Estimation of the residual strength of the soil on the landslide sliding surface is essential for analyzing reactivated landslides. This study investigated the influence of over-consolidation ratio (OCR) and shear rate on the residual strength of SM-type (silty sand) landslide soils in the Three Gorge Reservoir using ring shear tests under drained conditions. A series of ring-shear tests was performed in the present study using artificially overconsolidated samples subjected to different levels of consolidation stress to understand better the degree of variation in residual strength of SM-type landslide soil under various consolidation processes. Another concern addressed in the present study was the effect of shear rate on the residual strength of SM-type landslide soils loaded with the same consolidation stress. Samples were surrounded by water in the shear box during consolidation and shearing to prevent them from drying out
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