金沙江下虎跳滑石板滑坡破坏机理及稳定性分析

1996年10月28日发生在金沙江下虎跳峡口的滑石板滑坡,因堵塞金沙江、摧毁公路而引起高度重视。野外调查发现,滑石板滑坡是典型结构面控制的顺层基岩滑坡,层面和两组近于垂直层面的节理将边坡厚层灰岩切割成不同规模的菱形块体,长期的风化作用、重力、降雨、人工开挖公路等因素作用下,这些菱形块体从顺层稳定状态演化为稳定性较差的“悬挂”体,受河谷边坡斜向割切影响,表现为梯级叠次“悬挂”,最外边的“悬挂”体稳定性最差,最容易发生快速滑动。因此,该滑坡每次发生破坏滑动的体积不会很大,但是具有多次重复发生的特点,值得高度注意。

MECHANISM AND STABILITY OF HUASHIBAN LANDSLIDE ON THE DOWN TIGER-LEAP-GOEGE ALONG JINSHA RIVER

Huashiban landslide is located at the down Tiger-Leap-Gorge along the left bank of Jinshajiang river. It has caught wide attention because it obstructed the Jinshajiang river and destroyed the road on Oct. 28, 1996. The field work revealed that the landslide is a typical consequent rock landslide. The thick stratified limestone in the slope was cut into different diamond blocks by bedding plane and two steep sets joints. The original safe state of diamond blocks were transformed into unsafe state as "suspended" blocks due to many factors such as weathering, gravity, rainfall and road construction. Furthermore, the rock blocks present as step-like "suspended" blocks for the sidelong relation of the strikes of slope and strata. At the more outside of the slope, the blocks are more unstable. Therefore, the landslide is characterized by collapses of rock blocks with different sizes and can occur from time to time.