Strength Recovery of Landslide Soils from the Residual State of Shear

Abstract

A preexisting shear surface of a reactivated landslide has been subjected to repeated sliding and recession. During the sliding, the shear strength of shear zone has been reduced to the residual state, but the strength may be recovered from the residual state to some extent during a rest period. In this study, three landslide soils collected from the different large-scale landslide sites in Nepal and Japan are tested in a ring shear apparatus for the discontinued shear rest periods of 1, 3, 7, 15, and 30 days. Test results show that recovered strength measured in the laboratory is slightly noticeable after a rest period of 3 days, but recovered strength is lost after a very small shear displacement. This paper mainly focuses on the strength recovery behavior in highly plastic and less plastic soils from the residual-state of shear. The probable causes of the strength recovery are also discussed.

Effects of overconsolidation on the reactivated residual strength of remoulded deep-seated sliding zone soil in the Three Gorges Reservoir Region, China

“…In the reactivation test, the previous shearing was firstly stopped, but the sample that had been sheared to the residual state was still placed in the Bromhead apparatus. As the sliding body is still subjected to the shear force after sliding in the field (Bhat et al, 2014), during the rest period, the soil sample was always subjected to the vertical load and the shear force applied at the end of the previous ring shear test in order to better simulate the field conditions of the landslide. With reference to the minimum rest time selected in previous studies on residual strength (e.g., Angeli et al, 1996 Bhat et al, 2014).…”

“…As the sliding body is still subjected to the shear force after sliding in the field (Bhat et al, 2014), during the rest period, the soil sample was always subjected to the vertical load and the shear force applied at the end of the previous ring shear test in order to better simulate the field conditions of the landslide. With reference to the minimum rest time selected in previous studies on residual strength (e.g., Angeli et al, 1996 Bhat et al, 2014). If the overconsolidation effect on the reactivated residual strength can be observed within a short rest time, this effect will also exist for a long rest period.…”

Physical Model Test of Deformation Self-Adaptive Mechanism of Landslide Mass

“…At present, there are few systematic studies on the self-adaptive mechanism of the deformation of landslide accumulation, and most of them are focused on the strength regeneration of slip zone soils [6][7][8][9]. Li carried out consolidation and shear tests on the slip zone soil of the Sanmashan landslide and Outang landslide and verified that the strength regeneration of the slip zone soil resulted from the rise and fall of the reservoir water level [10].…”