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工程科学与技术:2024,56(1):237-244
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高山峡谷区山洪沟口泥沙堆积特征数值试验
(四川大学 山区河流保护与治理全国重点实验室,四川 成都 610065)
Numerical Experiment on Sediment Accumulation Characteristics at the Mouth of Flash Flood Gully in Alpine Canyon Area
(State Key Lab. of Hydraulics and Mountain River Eng., Sichuan Univ., Chengdu 610065, China)
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投稿时间:2022-05-26    
中文摘要: 山洪泥石流是高山峡谷区一种常见的自然现象,其运动过程通常伴随剧烈的沟道侵蚀,并在沟口形成显著的泥沙堆积体。由于高山峡谷地区山高谷深,难以通过实地调查及模型实验等传统的研究手段追踪沟床泥沙受山洪泥石流冲刷的运动过程,无法揭示山洪泥石流挟带泥沙的堆积形态及堆积体中泥沙粒径分布特征,易产生对灾害影响范围估计不足导致的区域人员伤亡和财产损失。为探究山洪沟口泥沙堆积形态和粒度特征,以概化的高山峡谷区山洪沟为研究对象,采用耦合的计算流体力学(CFD)与离散单元法(DEM)数学模型,模拟了受到不同流变特性山洪泥石流冲刷的泥沙颗粒在沟口的堆积过程,重点分析了山洪泥石流体积浓度对堆积区中不同粒径泥沙颗粒堆积发展过程的影响。结果表明:泥沙堆积体的发展速度随着山洪泥石流体积浓度增加呈现先增加后减小的趋势,过高的体积浓度促使堆积体形态发生改变。泥沙平均堆积距离随时间变化可以分为高速增加、初次减速、增速恢复和稳定发展4个阶段。随着粒径的增大,泥沙与堆积体中心的平均距离也增大但堆积分散程度减小。泥沙颗粒的分散程度随时间变化过程与泥沙粒径和体积浓度密切相关,可以使用具有3个参数的幂函数对这个过程进行预测。泥沙颗粒粒径的增大加快其在堆积体中的分散速度而山洪泥石流体积浓度的增大使泥沙颗粒的分散速度先增加后减小。研究可为进一步理解山洪泥石流堆积致灾机理提供科学依据。
Abstract:In alpine canyon, flash floods and debris flows are common. Usually, they are accompanied by strong gully erosion, and consequently create significant sediment accumulation in the gully mouth, which easily causes casualties and property losses in the region. It is difficult to track the movement process of gully bed sediment washed by flash floods and debris flows through field surveys, model experiments, and other traditional methods in alpine canyon areas due to high mountains and deep valleys. Therefore, it is impossible to provide information regarding the accumulation forms of sediment carried by mountain floods and debris flows as well as the distribution properties of sediment particle size in the accumulation body. To investigate the sediment accumulation morphology and particle size characteristics of mountain flood and debris flow, the generalized mountain gully area was taken as the research object. The coupled numerical methods of computational fluid dynamics (CFD) and discrete element method (DEM) were applied to simulation of sediment deposition process of mountain flood debris flow with different rheological characteristics. The effect of the volume concentration of mountain flood and debris flow on the accumulation process of sediment particles of different sizes in the accumulation area is analyzed in detail. As the volume concentration of mountain flood and debris flow increases, sediment accumulation rate first increases and then decreases. Furthermore, excessive volume concentration causes sediment to accumulate in a different form. The variations in sediment accumulation distance with time can be categorized into four stages: rapid increase, initial deceleration, recovery of growth and stable development. The variation of particle dispersion with movement time is of a power function, and the development rate is closely correlated with sediment particle size and volume concentration. There is a strong correlation between the degree of dispersion of sediment particles with time and the size and volume concentration of sediment particles. A power function with three parameters can be used to predict this process. Increased sediment particle size leads to an increase in the dispersion of sediment particles in the accumulation body. However, the increase in mountain floods and debris flows volume concentration causes the dispersion of sediment particles to increase at first and then decrease. The findings in this study can serve as a scientific basis for further understanding of mountain floods and debris flows.
文章编号:202200524     中图分类号:TV142    文献标志码:
基金项目:国家自然科学基金重点项目(52239006;51639007)
作者简介:第一作者:聂一品(1998-),男,博士生.研究方向:水力学及河流动力学.E-mail:nieyipin@163.com;通信作者:王协康,教授,E-mail:wangxiekang@scu.edu.cn
引用文本:
聂一品,兰玲,王协康.高山峡谷区山洪沟口泥沙堆积特征数值试验[J].工程科学与技术,2024,56(1):237-244.
NIE Yipin,LAN Ling,WANG Xiekang.Numerical Experiment on Sediment Accumulation Characteristics at the Mouth of Flash Flood Gully in Alpine Canyon Area[J].Advanced Engineering Sciences,2024,56(1):237-244.