河流泥沙10组分界粒径述评(摘要)

董耀华

(长江科学院 水利部江湖治理与防洪重点实验室，湖北　武汉　430010)

【摘　要】　本文从分界理论及分界阈值等方面，对泥沙分类、球体泥沙沉速、单矿质泥沙、黏粒溶胶、泥沙絮凝、泥沙触变、淤积初始干容重、沙波初始形态、推移质悬移质、床沙质冲泻质等冲积河流泥沙10组分界粒径(分界阈值上界为2.0mm、下界为0.001mm)进行了概述，给出了10组分界粒径的特性表和“谱系表”。10组分界粒径的本质“核心”是粗砂与细砂的划分：基于属性分类方法，10组分界粒径可划分为主要基于泥沙特性(第Ⅰ类)、依赖于泥沙与水流两者特性(第Ⅱ类)、有赖于泥沙、水流和河床演变3者特性(第Ⅲ类)等3种类型；基于确定性分类方法，又可划分为分界意义明确和分界阈值确定(A类)、分界意义明确性较差或者分界阈值确定性较弱(C类)、介于两者之间(B类)等3种类型。归纳提出了粗砂与细砂分界粒径、分界粒径与临界流速、泥沙沉速与起动流速等有关河流泥沙分界粒径的讨论问题和研究课题。

【关键词】　河流泥沙；分界粒径；分界阈值；粗细砂；临界流速；河床演变

基金项目：中央级公益性科研院所基本科研业务费项目“长科院水力学及河流动力学专业研究进展(2017—2018年)”(CKSF2017069+YB2)。

作者简介：董耀华(1966—　)，男，湖北蕲春人，教授级高级工程师，从事水力学及河流动力学研究。

E-mail:DONG_YH04@hotmail.com

Review on 10-Group Demarcating Grain-Sizes of River Sediment

DONG Yaohua

(Key Laboratory of River Regulation and Flood Control of MWR,Changjiang River Scientific Research Institute,Wuhan Hubei Province　430010)

Abstract:Based on demarcation theory and threshold size,10-group demarcating grain-sizes of alluvial river sediment with threshold sizes from maximum 2.0mm to minimum 0.001mm,which are related to sediment classification,falling velocity of spheric particle,mono-mineral sediment,division of clay and suspensoid sol,sediment flocculation,sediment thixotropy,initial dry density,initial sand-wave,division of bed-load and suspended-load,division of bed-material-load and wash-load,are firstly summarized.Then feature-table and“size-spectrum-table”of the 10-group demarcating grain-sizes are produced.The essential “core”of the 10-group demarcating grain-sizes lies in demarcation between coarse and fine sand.By means of attribute-based classification method,the 10-group demarcating grain-sizes can be divided into 3-types of Ⅰ-type(mainly dominated by sediment features),Ⅱ-type(relying on features of sediment and flow)and Ⅲ-type(depending on features of sediment,flow and fluvial processes),meanwhile they can also be divided into 3-classes of A-class(with definite demarcating meaning and certained threshold size),C-class(with less-definite demarcating meaning or less-certained threshold size)and B-class(between A-class and C-class)according to ascertainty-based classification method.Finally,discussion issues and further researches,associated with demarcating grain-sizes of river sediment,such as division between coarse and fine sand,relationship between demarcating grain-size and critical velocity,and relationship between settling velocity of sediment and incipient velocity of flow,are introduced.

Key words:River Sediment;Demarcating Grain-size;Threshold Size;Coarse and Fine Sand;Critical Velocity;Fluvial Processes