| 张晨笛,王兆印,李志威,李文哲.单个阶梯-深潭破坏的力学模型[J].水利学报,2014,45(12): |
| 单个阶梯-深潭破坏的力学模型 |
| A physically-based model of individual step-pool failure |
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| DOI： |
| 中文关键词: 阶梯-深潭 稳定性 临界流量 冲刷 |
| 英文关键词: step-pool stability critical discharge scour |
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| 中文摘要: |
| 阶梯-深潭系统是山区河流广泛分布的重要河床结构，其破坏机理对于认识山区河流稳定性及河床演变具有重要意义。针对单个阶梯-深潭，以关键石块为研究对象，综合考虑上游来水条件、下游冲刷和泥沙环境，建立单个阶梯稳定性的理论模型。基于理论模型，分析弱输沙条件下阶梯破坏的临界条件和失稳机制。结果表明：（1）河道比降、关键石块粒径、来流流量、下游冲刷和互锁作用是弱输沙条件下影响单个阶梯-深潭稳定性的关键因素。（2）来流恒定时阶梯下游冲刷降低阶梯稳定性。阶梯失稳临界流量随冲刷增强而减小，因此水流破坏作用表现为阶梯下游坡脚冲刷降低失稳临界流量，同时来流增加超过临界流量导致破坏。（3）互锁作用可有效提升阶梯稳定性，并在阶梯坡脚冲刷程度较大时明显提升失稳临界流量，这是阶梯在一般洪水中维持稳定的方式。 |
| 英文摘要: |
| Step-pool system is one of the most important and widespread bed forms in mountain rivers.The failure mechanism of step-pools， although poorly understood， plays a significant role on the stability and fluvial process of mountain river bed. Combined with effects of water discharge， downstream scour of the step and sediment environment，the forces of the keystone in step-pool formation are schemed and analyzed so as to advance a new theoretical model for individual step-pool stability. The model illustrates that channel gradient， keystone diameter， discharge， downstream scour angle and interlocking effect are the key factors that influence the stability. Downstream scour reduces step-pool stability if the discharge remains constant and bed load transport remains low. With stronger scour， critical discharge for failure becomes smaller. Therefore， strong flow breaches the step because the discharge surpasses the critical discharge lowered by downstream scour. Step-pool stability can be largely strengthened by interlocking effect， especially if downstream scour angle is large，which is a self-protection mechanism for step-pool system. |
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