Abstract
One of the world largest dams is under construction in the Yangtze Three Gorges area, China. This area is prone to landslides and rockfalls, and their occurrence and areal distribution are strongly controlled by the geological structure and materials of the slipped zone. Eighty-five percent of landslides in the basin is of re-sliding type, and the slipped zone is composed of sandy clay intermingled with detritus of mudstone and marl. After the construction of the dam, it is apprehended that many landslides recur due to the reduction of the effective stress caused by the rising of the water level in the reservoir. In order to elucidate the mechanizm of the landslides in the Three Gorges area, it is useful to take the strength-lowering concept of mudstone into consideration. Several ideas were suggested for this purpose.
