水库黄土岸坡塌岸预测模型及参数敏感性研究

Predictive modeling and sensitivity analysis of bank collapse on loess bank slopes in reservoirs

塌岸宽度预测是水电工程重要研究问题之一。现有的经验图解法基于塌岸最终稳定坡形进行塌岸宽度预测,难以反映塌岸的过程、特征,且对岸坡岩土体的物理力学性质考虑也较少。基于此,研究提出了基于极限平衡理论的黄土岸坡塌岸宽度预测模型,确定了模型关键参数取值,并对参数敏感性进行了分析。结果显示,基于极限平衡理论进行预测塌岸宽度时应选取合理的水下堆积系数,水下堆积系数随岸坡高度和水深的增加而增加。而岸坡角度对塌岸宽度的影响较小,且主要影响首次塌岸宽度,对后续塌岸宽度的影响不大。随着岸坡坡度的增大,塌岸宽度呈波动上升趋势。同时,塌岸参数敏感性分析结果显示,参数敏感性排序由大到小依次为岸坡高度、水下岸坡内摩擦角、水下岸坡黏聚力、水上岸坡重度、水深与岸高比、水上岸坡黏聚力、岸坡坡度、水上岸坡内摩擦角、水下岸坡重度,这与岸坡稳定性的参数敏感性分析结果基本一致。研究结果对黄土岸坡塌岸宽度预测具有重要意义。

Predicting the width of bank collapses is a key research challenge in hydropower projects.Current empirical graphical methods focus solely on the final state of bank failure,allowing them to predict only the collapse width.As a result,these methods do not sufficiently capture the characteristics of the bank collapse process.To address this issue,we developed a prediction model for bank collapse width based on limit equilibrium theory.Additionally,we analyzed the key parameters and their sensitivity within the model.The model effectively captures the process characteristics of bank collapses on loess bank slopes in reservoirs,while also taking into account the physical and mechanical properties of geotechnical materials.The results underscore the importance of selecting an appropriate underwater accumulation rate when predicting bank collapse width using limit equilibrium theory.At a constant ratio of water depth to bank slope height,the underwater accumulation rate increases linearly with the height of the bank slope.In contrast,the angle of the bank slope has minimal impact on the width of bank collapse.Specifically,it primarily influences the width of the initial bank collapse but has little effect on the widths of subsequent collapses.The results of the sensitivity analysis of collapsed bank parameters indicate that the ranking of parameter sensitivity,from highest to lowest,is as follows:bank slope height,submerged bank slope internal friction angle,submerged bank slope cohesion,submerged bank slope gravity,water depth-to-bank height ratio,slope of the bank,and repeated mentions of submerged bank slope internal friction angle and gravity.This ranking is largely consistent with the findings from the parameter sensitivity analysis of bank slope stability.The research findings are of significant importance for predicting the width of loess bank collapses.