三峡地区“14·9”极端暴雨型滑坡泥石流成灾机理分析

Mechanism of “14·9”rainstorm triggered landslides and debris-flows in the Three Gorges area

从三峡地区2014年9月极端降雨的强度、暴雨与地质灾害的关系和触发特大滑坡的地质特征角度出发,系统分析了"14.9"暴雨型特大滑坡泥石流的发育特征,分析认为"14.9"极端降雨是一次暴雨、局地特大暴雨的降水过程,过程主要集中于渝东北地区以及湖北巴东、秭归等地,最大单日降雨量达到403.4 mm,降雨强度明显超过川东地区区域内群发性岩质滑坡的降水临界值(250 mm/d),导致大范围地质灾害的发生;"14.9"暴雨红层地区滑坡主要是侏罗系与三叠系中上统岩层组成的层状碎屑岩斜坡失稳,破坏模式主要包括近水平顺层滑移破坏、滑移—拉裂破坏、滑移—溃屈破坏、变倾角旋转滑移破坏、斜倾顺层视倾向破坏和沿堆积层与基岩界面滑动等六种类型,且这些山体失稳后伴有泥石流灾害,形成更大范围的链生破坏。

From the relationship between extreme rainfall intensity and massive landslides characteristics in the Three Gorges area in September,2014（ ＂14. 9＂）,the analysis of development characteristics was carried out on the ＂14. 9＂rainstorm triggered lots of the landslides and debris flows. It was considered that the ＂14. 9＂extreme rainfall was a precipitation process of heavy rain and local extraordinary heavy rain, mainly concentrated in northeastern Chongqing as well as Badong and Zigui of Hubei. The maximum rainfall intensity was daily rainfall of 403. 4 mm,significantly more than the rainfall critical value（ 250 mm / d） of triggering landslides occurred in the region,leading to a wide range of geological disasters. The ＂14. 9＂landslides were mainly due to the instability of layered slope consisting of Jurassic and Triassic mid-upper strata,the failure mode mainly includes the six types,such as nearly horizontal bedding sliding,sliding-tensioning,slidingbuckling,rotational sliding,apparent dip sliding and accumulated layer landslide. Debris flow occured after the landslides sliding,forming a wider range of chain damages.