某水电站古崩滑体的成因机制及稳定性研究

该古崩滑体位于拟建水库坝址线上游27.7 km处,体积巨大,水库三个设计蓄水高程均在滑体剪出口之上,且该区属高烈度区,滑体一旦失稳,可能造成涌浪,甚至堵江和堰塞溃坝,影响严重。本文通过对古滑体地质背景、结构特征、变形破坏特征和形成条件分析,确定该滑体属崩滑性质。在漫长地质历史时期,受到较为频繁构造作用,斜坡岩体块裂化较明显,节理切割严重,产生了不利结构面的空间组合,一旦破坏面贯通,则导致斜坡沿着滑面崩滑下座,覆盖到冲洪积物堆积体之上。其稳定性通过定性、定量两方面评价,其中定量计算中,通过试验资料,结合参数反演确定计算参数,利用规范传递系数法和毕肖普法进行计算。评价结果表明,在天然、暴雨、蓄水及水位骤降工况下,滑体均处于稳定状态。而在考虑地震时,其稳定性迅速降低,滑体整体处于基本稳定状态。

STUDY ON FORMATION MECHANISM AND STABILITY OF ANCIENT CRUMBLE-SLIDING BODY IN A HYDROELECTRIC POWER STATION

The crumble-sliding body lies at 27.7km near lower reach of dam site line in a reservoir,and is tremendously huge.Three designed water levels are above the shearing zone of the ancient landslide and this district belongs to the high earthquake intensity zone.Once the landslide is active,which probably would create the turbulent waves,even landslide damming.According to investigation of ancient landslide geology situation,architectural feature,and the analysis of ancient landslide deformation feature,it is suggested that it belongs to crumble-sliding.In the long geological history,which was suffered from constrict stress frequently,so that the cracking of rock mass is obvious,the joints is cut intensely.Once the breakage surface is transfixed,the body will be crumble-sliding along slide surface,and would cover up the pile body of pluvial and alluvial deposits.The stability of sliding was evaluated by quality and quantitatively methods with calculating.The parametesr of slide surface was confirmed by experiment data and anti deducing.The computing technology adopted the Bishop method and the transmit coefficient method.It came to the conclusion that under nature,the rain storm circumstance,and storing water situation,the landslide is always in the stable state,but while earthquake,its stability will falls quickly to be fundamental steadies.