摘要:
由于分散土具有较高的水敏性导致其边坡易发生变形破坏,目前对分散土边坡的失稳破环特性及预测预报缺乏总体认识。本文基于分形理论设计了6个模型试验,通过近景摄影测量技术等研究了分散土边坡破坏模式,并提出了一种基于粗糙度参数(SRR)的适用于降雨诱发型分散土边坡失稳时间预报模型。试验结果表明:当分维值较大时(2.7687~2.8234),以渐进式水力侵蚀破坏为主;当分维值较小时(2.4977~2.6879),以滑动型破坏为主;当分维值适中时(2.6879~2.7687),以浅表层滑动型破坏为主,兼具侵蚀和滑坡的共同特征。分散土边坡失稳特性分为渗流和分散解体(初始侵蚀)、流固共存(等速侵蚀)和近饱和滑动(加速侵蚀)三阶段。本文采用斜率模型并选取SRR作为预测指标,通过改进切线角模型确定预测区域,可预测滑动型边坡发生失稳破坏的时间。本文发现滑动型边坡破坏时间预测结果RMSE均值为7.68,RE均值为2.4%。该研究成果对于认识分散土边坡破坏特性具有重要意义,并为降雨诱发滑动型滑坡的准确预报提供新模型。
关键词:
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边坡
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摄影测量
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降雨
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物理模型试验
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分散土
Abstract:
Due to the high water sensitivity of the dispersed soil, the slope is prone to deformation and failure. At present, there is a lack of overall understanding of the instability and failure characteristics and prediction of the dispersed soil slope. In this paper, six groups of model tests are designed based on fractal theory. The failure mode of dispersed soil slope is studied by close-range photogrammetry technology, and a prediction model of instability time of rainfall-induced dispersed soil slope based on roughness parameter (SRR) is proposed. The test results show that when the fractal dimension value is large (2.7687–2.8234), the progressive hydraulic erosion damage is dominant. When the fractal dimension value is small (2.4977–2.6879), it is dominated by sliding failure. When the fractal dimension value is moderate (2.6879–2.7687), it is dominated by shallow surface flow failure, which has the common characteristics of erosion and landslides. The instability characteristics of dispersed soil slope are divided into three stages: seepage and dispersed disintegration (initial erosion), fluid-solid coexistence (constant velocity erosion) and near-saturated slide (accelerated erosion). In this paper, the slope model is used and SRR is selected as the prediction index. The prediction area is determined by improving the tangent angle model, which can predict the time of instability and failure of the flow-slip slope. In this paper, it is found that the mean RMSE of the prediction results of the failure time of the sliding failure slope is 7.68, and the mean RE is 2.4%. The research results are of great significance for understanding the failure characteristics of dispersed soil slopes, and provide a new model for the accurate prediction of rainfall-induced sliding failure landslides.