2017 Volume 73 Issue 1 Pages 106-115
This paper focused on inducement of landslide and performed two types of stress control tests by reducing normal stress (effective mean stress) under controlling shear stress constant in both triaxial compression and ring shear tests to simulate landslide behavior. In both tests, yield and failure stresses were properly obtained as a threshold of displacement generation and a breaking point. As a result, the thresholds of displacement generation were especially shown to be expressed by the strength line described by the shear resistance angle of cohesive soil. In case of incipient sliding type landslide, the threshold of displacement generation was shown to be indicated by the peak strength line determined by displacement control ring shear test. On the other hand, it was described by the residual strength line in case of re-sliding type landslide. The shear resistance angle that represents the threshold of displacement generation revealed the shearing history of cohesive soil. In re-sliding type landslides, the displacement of landslide is repeatedly proceeded, but it is generally limited. The design work of landslide with use of strength constants was newly interpreted as aiming at the threshold for displacement increase in landslide.
In re-sliding type stress control test, displacement behavior was found to be brittle different from that of incipient sliding type landslide. Since consolidation effect in re-sliding type landslide seems great, the effect of consolidation on yield stresses was systematically investigated by both stress control and displacement control tests. The yield stress clearly increased with overconsolidation ratio and was consistent in both tests.