Abstract: Due to the bedding weak interlayer with gentle dip angle along the slope of Yangtze-to-Huaihe River Water Diversion in Jianghuai watershed, parts of canal slope have been excavated for a long time during construction, resulting in increased deformation of interlayer and slope collapse. Preliminary analysis reveal that the strength of the interlayer rock mass is close to residual state under the condition of large deformation. To investigate the influence of interlayer on slope stability, we collected undisturbed soil samples from some deep excavated canal sections and examined the strength characteristics of weak interlayer and carried out slope stability analysis, and also put forward some suggestions of treatment measures. Stability analysis unveil that the canal slope stability depends on the position, tendency and mechanical indexes of the weak interlayer in canal slope. The weak interlayer of canal slope has been in the state of residual strength under the continuous action of large deformation, which leads to local collapse. We suggest to reinforce the slope with retaining measures such as anti-slide pile and anchorage in association with slope drainage in line with the layered structure and strength characteristics of the canal slope.

Key words: slope stability, weak interlayer, residual strength, anti-slide pile, anchorage, Yangtze-to-Huaihe River Water Diversion