关键词: 滑坡-碎屑流, 降雨, 成因机制, 裂隙扩展判据, 启动判据

Abstract: On July 10, 2013, a high-position landslide-debris flow was triggered by the heavy rainfall at Wulipo Sanxi village, Dujiangyan city, Sichuan province. The landslide-debris flow caused serious damages to Sanxi village. On the basis of further field investigation and previous research results, the formation mechanism and evolution process of the Wulipo landslide-debris flow are analyzed. Considering the actual mechanical behavior of the Wulipo landslide, the crack extending criterion under hydrostatic pressure and landslide start-up criterion under rainfall are calculated. The results show that the evolution process of the Wulipo landslide-debris flow includes following steps: formation of unloading crack, crack extending under hydrostatic pressure, slope sliding along the potential sliding surface under the effects of both hydrostatic and hydrodynamic pressures, rift trough forming, landslide reactivation due to heavy rain, rock blocks falling and accelerating, shoveling and moving along the valley, stacking and stop moving. By deducing minimum depth of water in the crack leading to crack automatically developing, critical water height in back crack and critical rainfall intensity causing slope instability, it is concluded that the crack could automatically develop when the depth of water in the crack reached 11.3 m; and the slope would lose its stability once the height of the water level in back crack reached 9.8 m.

Key words: landslide-debris flow, rainfall, formation mechanism, crack extending criterion, landslide start-up criterion