摘要:
千将坪滑坡是三峡水库蓄水后,库区发生的第一例灾害性滑坡。本文以千将坪滑坡地质结构为基础,结合滑坡发育特征,采用敏感性分析方法,研究了水库蓄水和降雨作用下滑坡稳定性系数随着一系列对水作用敏感的滑坡参数的变化规律,探讨了水在千将坪滑坡中的定量作用机理。研究结果显示,水在千将坪滑坡的中的作用,以其对切层段泥岩抗剪强度的弱化作用对滑坡稳定性的影响最为显著,其余依次为对滑坡施加浮托力、弱化顺层段主滑带抗剪强度和增大滑体容重,地下水位上升、滑带内孔隙水压力增大对滑坡稳定性的影响微弱。千将坪滑坡的发生是三峡水库蓄水和持续性降雨叠加作用的结果,但是水库蓄水对滑坡稳定性的影响程度大于降雨,后者对滑坡的发生可能起了触发因素的作用。
Abstract:
Qianjiangping landslide was the first catastrophic landslide occurred in the reservoir area of the Three Gorges dam after its impoundment.Following analyzing characteristics of the landslide,variation of its factor of safety(F_s) under the influence of both rise of reservoir water level and durative rainfall was investigated in this paper using sensitive analysis with a consideration of a series effects of water on the landslide,such as: weakening of shear strength of the landslide’s slip zone,increasing unit weight of the landslide materials,imposing a uplift water pressure on the landslide,and rising groundwater table.It was found among these effects,weakening of shear strength of the lower section of the landslide’s slip zone,which developed crossing bedding planes of mudstone,had the strongest influence on the landslide’s stability,followed by those of uplift water pressure,weakening of shear strength of the slip zone’s upper section along the bedding plane of shale,increasing of unit weight of landslide’s materials,whereas rising of groundwater table had little influence on the landslide.Results of this study showed that occurrence of Qianjiangping landslide was a consequence of combined influence of impoundment of Three Gorges’ dam and durative rainfall.However,it seems that influence of the former was much greater that the latter.
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