Effect of strength decrease of rock on the displacement of Tangjiashan Landslide in 2008 Wenchuan Earthquake, China

Abstract

The sliding mass of Tangjiashan Landslide in 2008 Wenchuan Earthquake moved more than 350 m (toe part) horizontally. Based on the field investigation, peak and residual strength of rock (strictly, rock discontinuities) were evaluated. Then, the displacement was calculated using extended Newmark and Janbu method (extended NJ method). In order to give a rapid evaluation of displacement in field, more attention was paid on the effect of strength decrease of rock during sliding. The result shows that if the strength did not decrease largely after a short displacement, the displacement would be much less than the actual displacement during the earthquake. In addition, the sliding duration was significantly affected by the minimum value of displacement for the residual state.