摘要
【目的】研究珊瑚砂形态对单颗粒沉积物起动特征的影响,为准确描述珊瑚砂沉积物在极端波浪动力作用下的起动特征提供参考。【方法】分析传统基于陆源碎屑颗粒的沉积动力学公式对珊瑚砂颗粒的不适用性,以9种典型形态的珊瑚砂颗粒为研究对象,利用数值计算方法,研究珊瑚砂颗粒粒径、密度对其起动特征的影响,探讨极端波浪动力条件下珊瑚砂的动力学响应差异。【结果】9种形态珊瑚砂的等容粒径为筛分粒径的0.589~1.696倍,基于等容粒径计算的波致剪应力、起动剪应力分别为基于筛分粒径计算的0.759~1.316倍、0.603~1.951倍。使用传统沉积公式计算得到的珊瑚砂的沉积动力学比值是实际的0.795~1.428倍。【结论】在应用传统石英砂沉积动力学公式评估珊瑚砂在波浪作用下被扰动的适用性时,会高估波浪对针状珊瑚砂的扰动能力,而低估对板状珊瑚砂的扰动能力。因此,在使用传统陆源碎屑沉积动力学公式研究珊瑚砂水动力学时,应当充分考虑珊瑚砂颗粒形态的特殊性,使用更适用于珊瑚砂的粒径描述方法以及更加准确的密度确定方法,并根据理论分析对计算结果进行修正。
[Purposes]The paper sims to analyze the effect of coral sand morphology on the starting behaviors of single-grained sediments,and to provide a reference for accurately describing the initiation of motion behavious of coral sands under hydrodynamic action of extreme waves.[Methods]We briefly analyse the difficulties in directly applying traditional equations to coral sands.Furthermore,we investigate the effect of particle size and density on initiation of motion behaviors and how nine differently shaped coral sand particles respond to extreme wave conditions through numerical calculation approaches.[Findings]The nominal diameter of these nine differently shaped coral sands is 0.589~1.696 times of their sieving diameters,followed by their corresponding wave-induced shear stress being 0.759~1.316 times,and the critical shear stress being 0.603~1.951 times of those predicted with their sieving diameters.This results in the ratio of wave-imposed shear stress to stress of sediment threshold of motion being 0.795~1.428 times of the original estimations using traditional formulae.[Conclusions]When applying quartz-based formulae to assess the possibility of coral sands being mobilized by waves,the effect of wave action may be overestimated for acicular-shaped coral sands,and underestimated for plate-shaped coral sands.Therefore,the shape of coral sand particles should be fully considered when characterizing their sediment dynamic behaviors,and therefore numerical modeling results should be adjusted accordingly with respect to particle shapes.Moreover,a more suitable description of grain size and a more accurate method measuring particle density is urgently desired for coral sand when performing hydrodynamics analysis of them.
作者
吴凌云
赵中伟
李伟
WU Lingyun;ZHAO Zhongwei;LI Wei(Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Guangzhou 510301,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《长沙理工大学学报（自然科学版）》
CAS
2023年第4期27-36,共10页
Journal of Changsha University of Science and Technology:Natural Science
基金
国家重点研发项目(2021YFC3100501)
海南省科技计划三亚崖州湾科技城联合项目(420LH048)。
关键词
珊瑚砂
波浪
沉积动力学
等容粒径
起动剪应力
coral sand
wave
sediment dynamics
nominal diameter
shear stress at threshold of motion
