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chapter 3.3.2.2 River Transport and Sedimentation Effects课程教案、知识点、字幕

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河流在运动过程中

将侵蚀的物质以不同的方式向下游搬运

并在一定条件下会将这些物质沉积下来

所以这节课我们来学习河流的搬运和沉积作用

河流的搬运作用非常强大

从方式上来看主要有四种

一些可溶性的盐和胶体物质

通常会以溶液的方式随着河流向下迁移

也就是溶运

颗粒细小的砂和黏土颗粒

则通过悬浮在水中的方式向下游迁移 也就是悬移

悬移也是河流搬运最重要的方式之一

比如黄河每年以悬移的方式搬运的泥沙

达到6.72亿吨

粒径较大的一些块石 卵石以及粗砂

它在水流的作用下会呈跳跃的方式向下游运动

也就形成了跃移 而巨大的块石

和砾石在水流的作用下

会沿着河床底部通过滚动

或者是滑动的方式向下游发生推移

在这四种搬运方式中

溶运又是一种化学搬运方式

而其它的三种都是机械的搬运方式

河流在运动过程中能量将不断损失

当河流所挟带的泥沙 砾石等

物质超过了河流的搬运能力的时候

这些物质便在重力的作用下逐渐的沉积下来

这就是河流的沉积作用

所形成的沉积物我们叫它 冲积物

由于河流在不同地段它的流速有很大差异

所形成的冲积物差异也比较大

山区河流比较快

所沉积的物质通常是以粒径较大的卵砾石为主

当河流由山区进入平原的时候

流速会急剧的降低

那么所挟带大量物质会迅速沉积下来

常会形成扇状的冲积地形

也就是冲积扇 比如北京平原

它就是西边的永定河和东北部的潮白河

形成的两个大的冲积扇构成的

在河流的下游主要是由细小颗粒

沉积形成的广阔的冲积平原

比如华北大平原 它就是由黄河下游

海河以及淮河冲积形成的

在河流的入海口处 流速几乎降为零

挟带的细小的泥沙绝大部分要沉积下来

从而形成三角洲

另外在洪水期由于河流断面扩大

引起河漫滩洪水的流速降低

那么洪水挟带颗粒细小的泥沙

将沉积在河床冲积物上

从而形成下部为卵砾石 粗砂组成的河床冲积物

上部为粉砂或黏土组成的河漫滩冲积物

也就是下粗上细的一种沉积结构

这种现象在河流的中下游经常看到

称为二元结构

受河流长距离搬运及水流分选作用的影响

使河流的冲积物 具有分选性好

磨圆度高 层理清晰 成份复杂等特点

冲积物可以说在自然界中广泛分布

在将冲积物作为建筑物地基的时候

那么卵砾石地基它承载力相对比较高

而黏土它的地基承载力相对低

另外还要注意两种不良的冲积物

一种是软弱土层 比如说牛轭湖中淤泥沉积

另外一种是易发生液化的粉砂层

砂 卵石和砾石层可以说是良好的建筑材料

但是当坝下面覆盖有很厚的冲积层时

容易形成一个渗流通道

这个时候应做好防渗措施

另外厚度稳定延续性好的卵砾石层

通常是丰富含水层

可以作为良好的供水水源

我们知道区域的地壳抬升

将降低河流侵蚀基准面

从另一个方面也就是说增加了河流的下蚀速率

从而使河床被迅速下切

这样原来的河谷的谷底将相对抬升到洪水位以上

并在河谷两侧形成阶梯状的地形

我们称为河流阶地

所以说河流阶地的形成是地壳上升

运动和河流地质作用共同的一种结果

对于一条较大的河流往往有多级阶地

沿着河谷呈条带状分布

为了区分通常将它们进行编号

从下往上编号依次增加

分别为一级阶地 二级阶地 三级阶地等等

所以对于同一条河流而言

阶地的编号越大 形成的年代也就越老

根据河流阶地组成物质的不同

可以把阶地分三种类型

一种是由被侵蚀的基岩构成

只有很少的冲积物 也就是侵蚀阶地

这类阶地一般是在山区

地壳上升比较快 河流下切强烈而造成的

河流在下切过程中 如果切穿了已有的冲积层

并切入下部基岩一定深度

形成的阶地成为基座阶地

这类阶地上部为河流的冲积物

下部是基岩 如果是说没有切穿已有的冲积层

形成的阶地都是由河流冲积物组成

叫做冲积阶地

这节课我们学习了河流的搬运和沉积作用

通过这节课的学习

同学们要了解河流的四种搬运方式

掌握冲积物的特点及工程意义

河流的二元结构 河流阶地及其类型

从而达到在野外能够识别冲积物

判断阶地及其类型

Geology and Engineering Geology课程列表:

0 Introduction

-0.1 Human Engineering Activities and the Geological Environment

--Chapter 0.1 Human Engineering Activities and the Geological Environment

-0.2 Tasks for Engineering Geology

--Chapter 0.2 Tasks for Engineering Geology

-0 Quiz--Homework

1 The Earth and the Crust

-1.1 Formations and Evolution of the Earth

--Chapter 2.1 Formations and Evolution of the Earth

-1.2 Basic Attributes of the Earth

--Chapter 1.2 Basic Attributes of the Earth

-1.3 Construction of the Geo-sphere and the Geological Processes

--Chapter 1.3 Construction of the Geo-sphere and the Geological Processes

-1 Quiz--Homework

2 Endogenic Geological Process

-2.1 Crustal Movement

--Chapter 2.1 Crustal Movement

-2.2 Magmatism

--Chapter 2.2 Magmatism

-2.3 Metamorphism

--Chapter 2.3 Metamorphism

-2.4 Earthquake

--Chapter 2.4 Earthquake

-2 Quiz--Homework

3 Exogenic Geological Process

-3.1 Introduction

--Chapter 3.1 Introduction

-3.2 Weathering Effects

--chapter 3.2.1 Physical Weathering

--chapter 3.2.2 Chemical and Biological Weathering

--chapter 3.2.3 Weathering Products and Influencing Factors of the Weathering Process

-3.2 Weathering Effects--Homework

-3.3 Geological Effects of the Flowing Surface Water

--chapter 3.3.1 Geologic Process of Temporary Torrents

--chapter 3.3.2.1 River Erosion Effects

--chapter 3.3.2.2 River Transport and Sedimentation Effects

-3.3 Geological Effects of the Flowing Surface Water--Homework

-3.4 Geological Effects of Winds

--Chapter 3.4 Geological Effects of Winds

-3.4 Geological Effects of Winds--Homework

-3.5 Geological Effects of Glaciers

--Chapter 3.5 Geological Effects of Glaciers

-3.5 Geological Effects of Glaciers--Homework

-3 Quiz Easy--Homework

-3 Quiz Enhanced--Homework

4 Minerals and Rocks

-4.1 Minerals

--Chapter 4.1.1 Minerals and Their Morphological Characteristics

--4.1.2 Minerals and Rocks-Mineral Characteristics-Physical and Mechanical Prop

--Chapter 4.1.3 Visual Identification of Common Minerals

-4.1 Minerals--Homework

-4.2 Magmatic Rocks

--Chapter 4.2.1 Main Mineral Compositions of Magmatic Rocks

--Chapter 4.2.2 Texture and Structure of Magmatic Rocks

--Chapter 4.2.3 Common Classification and Identification Methods for Magmatic Rocks

--Chapter 4.2.4 Basic Characteristics of Common Magmatic Rocks Ⅰ

--Chapter 4.2.5 Basic Characteristics of Common Magmatic Rocks Ⅱ

-4.2 Magmatic Rocks--Homework

-4.3 Sedimentary Rocks

--Chapter 4.3.1 Material Compositions of Sedimentary Rocks

--Chapter 4.3.2 Texture and Structure of Sedimentary Rocks

--Chapter 4.3.3 Basic Characteristics of Common Sedimentary Rocks

-4.3 Sedimentary Rocks--Homework

-4.4 Metamorphic Rocks

--Chapter 4.4.1 Mineral Composition and their Texture andStructure

--Chapter 4.4.2 Basic Characteristics of Metamorphic Rocks

-4.4 Metamorphic Rocks--Homework

-第4章 Quiz Easy--Homework

-第4章 Quiz Enhanced--Homework

5 The Geologic Times

-5 The Geologic Times

--Chapter 5 The Geologic Times

-5 Quiz--Homework

6 The Geological Structure

-6.1 Horizontal Structure and Dipping Structure

--Chapter 6.1 Horizontal Structure and Dipping Structure

-6.2 Fold Structure

--Chapter 6.2 Fold Structure

-6.3 Fault Structure

--Chapter 6.3.1 Joint

--Chapter 6.3.2 Characteristics and Types of Faults

--Chapter 6.3.3 Fault Identification in the Wild

-6 Quiz Easy--Homework

-6 Quiz Enhanced--Homework

7 Geological Maps

-7.1 ntroduction

--Chapter 7.1.1 Types of Geological Maps

--Chapter 7.1.2 Scale of Geological Maps

-7.2 Presentation of the Geological Maps

--Chapter 7.2.1 Formation Lithology

--Chapter 7.2.2 Geological Structure

--Chapter 7.2.3 Contact Relations Between Stratas

-7.3 Reading and Analysis of the Geological Maps

--Chapter 7.3 Reading and Analysis of the Geological Maps

-7 Quiz Easy--Homework

-7 Quiz Enhanced--Homework

8 Ground Water

-8.1 Basic Conceptuals

--Chapter 8.1 Basic Conceptuals

-8.1 Basic Conceptuals--Homework

-8.2 Reservation and Movements of Ground Water

--Chapter 8.2 Reservation and Movements of Ground Water

-8.2 Reservation and Movements of Ground Water--Homework

-8.3 Movements of the Ground Water

--Chapter 8.3 Movements of the Ground Water

-8.3 Movements of the Ground Water--Homework

-8.4 Ground Water Quality

--Chapter 8.4 Ground Water Quality

-8.4 Ground Water Quality--Homework

-8.5 Ground Water Related Issues on Engineering Geology

--Chapter 8.5 Ground Water Related Issues on Engineering Geology

-8.5 Ground Water Related Issues on Engineering Geoligical Problem--Homework

-8 Quiz Easy--Homework

-8 Quiz Enhanced--Homework

9 Geological Engineering Attributes of Soils

-9.1 Soil Mass

--Chapter 9.1 Soil Mass

-9.1 Soil Mass--Homework

-9.2 Attributes of Soils

--Chapter 9.2.1 Physical Properties of Soil

--Chapter 9.2.2 Water-Physical Properties of Soil

--Chapter 9.2.3 Mechanical Properties of Soil

-9.2 Attributes of Soils--Homework

-9.3 Engineering Classification of Soils

--Chapter 9.3 Engineering Classification of Soils

-9.4 Special Soils and Its Engineering Attributes

--Chapter 9.4.1 Soft Soil and Its Engimeering Attributes

--Chapter 9.4.2 Loess and Its Engineering Attributes

--Chapter 9.4.3 Expansive Soil adn Its Engineering Attributes

-9.4 Special Soils and Its Engineering Attributes--Homework

-9 Quiz Easy--Homework

-9 Quiz Enhanced--Homework

10 Geological Engineering Attributes of Rocks

-10.1 Introduction

--Chapter 10.1 Introduction

--10.1 Introduction--Homework

-10.2 Physical and Water-Physical Properties of Rocks

--Chapter 10.2 Physical and Water-Physical Properties of Rocks

--10.2 Physical and Water-Physical Properties of Rocks--Homework

-10.3 Mechanical Properties of Rocks

--Chapter 10.3.1 Deformation Characteristics

--Chapter 10.3.2 Strength

--10.3 Mechanical Properties of Rocks--Homework

-10.4 Structural Plane and Structural Body of Rock Mass

--Chapter 10.4 Structural Plane and Structural Body of Rock Mass

--10.4 Structural Plane and Structural Body of Rock Mass--Homework

-10.5 Features and Mechanical Properties of the Structural Plane

--Chapter 10.5.1 Properties of Structural Plane

--Chapter 10.5.2 Mechanical Properties of Structural Plane

--10.5 Features and Mechanical Properties of the Structural Plane--Homework

-10.6 Mechanical Properties of Rock Mass

--Chapter 10.6 Mechanical Properties of Rock Mass

--10.6 Mechanical Properties of Rock Mass--Homework

-10.7 Engineering Classification of Rock Mass

--Chapter 10.7.1 Engineering Classification of Rock Mass Ⅰ

--Chapter 10.7.2 Engineering Classification of Rock Mass Ⅱ

--10.7 Engineering Classification of Rock Mass--Homework

-10 Quiz Easy--Homework

-10 Quiz Enhanced--Homework

11 Analysis on the Stability of Slopes

-11.1 Slope Deformation and Destruction

--Chapter 11.1.1 Slope Deformation

--Chapter 11.1.2 Slope Destruction

-11.1 Analysis on the Stability of Slopes--Homework

-11.2 Factors on the Stability of Slopes

--Chapter 11.2 Factors on the Stability of Slopes

-11.3 Analysis on the Stability of Slopes

--Chapter 11.3 Analysis on the Stability of Slopes

-11.3 Analysis on the Stability of Slopes--Homework

-11.4 Structural Analysis Method on Rocky Slope Stability

--Chapter 11.4.1 Stereographic Projection Method Ⅰ

--Chapter 11.4.2 Stereographic Projection Method Ⅱ

-11.5 Measures for Preventing and Controlling the Slope Deformation

--Chapter 11.5 Measures for Preventing and Controlling the Slope Deformation

-11.5 Measures for Preventing and Controlling the Slope Deformation--Homework

-11 Quiz Easy--Homework

-11 Quiz Enhanced--Homework

12 Geological Engineering Analysis on Stability of the Adjacent Rocks of Underg

-12.1 Underground Caverns and the Stress Distribution

--Chapter 12.1 Underground Caverns and the Stress Distribution

-12.1 Underground Caverns and the Stress Distribution--Homework

-12.2 Deformation and Destruction of the Adjacent Rocks

--Chapter 12.2.1 Brittle Adjacent Rock

--Chapter 12.2.2 Plastic Surrounding Rock and Surrounding Rock Stability Sign

-12.3 Factors on Stability of the Adjacent Rocks

--Chapter 12.3 Factors on Stability of the Adjacent Rocks

-12.4 Measures for Preventing Instability of the Adjacent Rocks

--Chapter 12.4 Measures for Preventing Instability of the Adjacent Rocks

-12 Quiz--Homework

13 Analysis on the Stability of the Rock Mass of the Ground Work

-13.1 Dam Foundation of the Water Conservancy Project

--Chapter 13.1.1 Dam Types and Requirements for Engineering Geological Conditions

--Chapter 13.1.2 Deformation Failure Mode and Stability Analysis

-13.2 Common Methods of Foundation Constructions

--Chapter 13.2 Common Methods of Foundation Constructions

-13 Quiz--Homework

14 Geological Engineering Analysis on the Reservoir Construction

-14.1 Reservoir Leakage

--Chapter 14.1 Reservoir Leakage

-14.2 Stability of the Reservoir Bank

--Chapter 14.2 Stability of the Reservoir Bank

-14.3 Reservoir Surrounding Immersions and Sedimentations

--Chapter 14.3 Reservoir Surrounding Immersions and Sedimentations

-14 Quiz--Homework

15 Methods and Technics of Engineering Geological Exploration

-15.1 Introduction

--Chapter 15.1 Introduction

-15.2 Engineering Geological Mapping

--Chapter 15.2.1 Research Content

--Chapter 15.2.2 Structural Plane Statistics

-15.3 Engineering Geological Exploration and Field Experiments

--Chapter 15.3 Engineering Geological Exploration and Field Experiments

-15.4 Instructions on the Geological Compass

--Chapter 15.4 Instructions on the Geological Compass

- Quiz--Homework

chapter 3.3.2.2 River Transport and Sedimentation Effects笔记与讨论

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