Numerical analysis on influence of principal parameters of topography on hillslope instability in a small catchment
Numerical analysis on influence of principal parameters of topography on hillslope instability in a small catchment
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DOI：
10.1007/s12665-014-3819-z
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发表时间：
2015-05
影响因子：
2.8
通讯作者：
K. Acharya;N. Bhandary;R. Dahal;R. Yatabe
中科院分区：
文献类型：
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作者：
K. Acharya;N. Bhandary;R. Dahal;R. Yatabe
本研究旨在确定构成地形的三个主要参数（斜坡倾斜度、土壤深度和斜坡长度）对日本西部四国岛东福贝格小集水区山坡不稳定性的影响。2004年10月19日至20日的台风造成汇水区共7处斜坡断裂，但同年其他不同强度的降雨事件并未造成断裂。为了了解这三个主要参数的影响，在GeoStudio中通过改变三个参数在其允许范围内的变化来构建斜坡剖面，从而对渗流和边坡稳定性进行了数值模拟（GeoStudio教程包括学生版课程，Geo-Slope International Ltd., Calgary, 2005 v.4）。利用孔隙水压力和坡体质量因主要参数值变化而产生的变化来解释安全或失稳系数的变化。结果表明：(1)在东福begawa地区，失稳随三个参数值的增大而增大，安全系数呈显著的减小趋势；(2)边坡倾角和土壤深度通过非饱和带含水率和坡体动员力的变化对失稳产生影响；非饱和带含水率变化不大，说明坡长引起的失稳主要受坡体质量变化的控制。总体而言，本研究较详细地研究了在相同的水文和岩土参数模拟条件下，坡面失稳随地形主要参数的变化规律。
This study was conducted to identify the influence of three principal parameters constituting topography (slope inclination, soil depth, and slope length) on hillslope instability in a small catchment, known as Higashifukubegawa of Shikoku Island, western Japan. The typhoon rainfall of 19–20 October 2004 was significant in causing a total of seven slope failures in the catchment, though other rainfall events of various intensities in the same year did not cause failure. To understand the influence of the three principal parameters, numerical modeling of seepage and slope stability was performed in slope profiles constructed by varying the three parameters across their permissible range prepared from the seven slope failures of Higashifukubegawa in GeoStudio (GeoStudio Tutorials includes student edition lessons, Geo-Slope International Ltd., Calgary, 2005 v.4). The change in porewater pressure and slope mass weight due to variation in values of principal parameters was used to interpret the change in factor of safety or instability. The results showed that (1) instability increases with increase in the values of all three selected parameters across their range in Higashifukubegawa with remarkable decreasing trend in factors of safety, (2) slope inclination and soil depth were observed to affect instability through change in both unsaturated zone moisture content and mobilizing force of slope mass, (3) but with slope length, the unsaturated zone moisture content was not found to change considerably which implies that the instability due to slope length is mainly governed by change in slope mass weight. Overall, this study has dealt in great detail with how hillslope instability changes with principal parameters of topography under the same simulating conditions of hydrological and geo-mechanical parameters.