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Landsides:中国四川盆地东部降雨诱发缓倾红层滑坡灾变机理
作者:管理员    发布于:2015-10-03 14:19:51    文字:【】【】【
摘要:岩土工程领域权威期刊中文摘要速递

摘要:红层在四川盆地东部广泛分布,往往被称为滑坡易发地层。红层倾角一般不大于10°,这远小于层间土体的内摩擦角。因此,理论上该地层不会发生滑坡现象。文中以中国西南部发生的青柠滑坡为例,采用现场调查、数值模拟、室内环剪试验等手段综合研究降雨对缓倾红层滑坡的影响。研究结果显示可能的滑坡灾变机理如下:(1)雨水自滑坡后方裂隙渗入,致使孔隙水压力提升,从而使得有效应力降低、下滑力提高,逐渐造成边坡失稳。在青柠滑坡灾变之前,其内部孔隙水压达到21.8m。当安全系数降低到1.015时,滑坡灾变缓慢启动。(2)当滑坡启动时,滑动区土地处于不排水剪切状态,其抗剪强度快速衰减至临界值,从而造成坡体快速失稳。期间,该滑坡滑动面土体残余抗剪强度下降至25.9kpa,而此时的孔隙水压达到118.3kpa。本文可为研究四川盆地东部缓倾红层滑坡灾变提供基础理论依据,亦可用于全球其他类似地质环境区。

关键字:降雨诱发型滑坡;缓倾红层;孔隙水压;滑带土;残余抗剪强度

Title】:Mechanisms of rainfall-induced landslides in gently inclined red beds in the eastern Sichuan Basin, SW China

Author】:Zhang, M.; Yin, Y.; Huang, B.

Jourrnal】:Landslides, 2015, 12(5), 973-983

Abstract】:Red beds are widespread in the eastern Sichuan Basin, SW China, and are often called “landslide prone strata”. The dip angle of these red beds is commonly less than 10°, which is much less than the angle of internal friction between the bedding planes. Thus, in theory, failure will not occur along the bedding planes in such strata. We used field methods, numerical modeling, and ring shear tests to investigate the effects of rainfall on landslides in shallow-dipping red beds, using the Qingning landslide in SW China as an example. Our results suggest that the probable mechanisms leading to failure are (1) permeation of rainfall through the cracks at the back of the landslide site that increases the hydrostatic water pressure, which adds to the sliding stress and reduces the effective stress on the failure surface, gradually destabilizing the mass. In the Qingning landslide, the maximum water pressure was as high as 21.8 m before failure. When the factor of safety decreased markedly to 1.015, the sliding mass started to slowly slide. (2) As sliding takes place, the sliding zone soil is under undrained shear and its shear strength decreases sharply to a critical value, which promotes rapid sliding. In the Qingning landslide, the shear resistance of the sliding zone soil decreased markedly to 25.9 kPa as the pore water pressure increased to 118.3 kPa. This study may provide a theoretical basis for landslide forecasting in gently inclined red beds of the eastern Sichuan Basin as well as in similar geological settings worldwide

Keywords】:Rainfall-induced landslide;Gently inclined red beds;Water pressure;Sliding zone soil;Shear resistance

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