土力学第六章土压力精品PPT课件

岩土工程研究所
第一节 概述 Introduction
What is earth pressure?
Earth pressure: The pressure applied on a retaining wall from soil
岩土工程研究所
第一节 概述 Introduction
Types of earth pressure?
f
45 2
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3 p a (z q )t2 g (4 5 2 ) (z q )K a
be at-rest pressure. The soil is in at-rest state.
主动极限平衡状态: Active state: plastic equilibrium with lateral expansion taking place. 被动极限平衡状态: Passive state: plastic equilibrium with lateral compression taking place. 静止平衡状态: At-rest state: elastic equilibrium with no lateral strain taking place.
第二节 朗肯土压力理论
Rankine’s theory
Active earth pressure in cohesionless soils
The wall moves away from the earthfill, Vertical stress is major principal stress
被动土压力 Passive earth pressure:The wall is caused to move towards the soil being supported, and the horizontal soil pressures are refereed to as
passive pressure. The soil is in passive state.
第六章 土压力
Chapter 6 Earth Pressure
Research Institute of Geotechnical Engineering,
岩土工程研究所
Hohai University
第一节 概述 Introduction
土压力概念 What is earth pressure? 土压力种类： Types of earth pressure 静止土压力： Earth pressure at rest
静止土压力 Earth pressure at rest:The wall is rigid and does not yield, that is there is no movement taking place, the horizontal soil pressures are said to
P0 12H2K0
第二节 朗肯土压力理论
Rankine’s theory
Active earth pressure in cohesionless soils
The wall moves away from the earthfill, Vertical stress is major principal stress
岩土工程研究所
第一节 概述 Introduction
At-rest earth pressure?
Under natural conditions of deposition, with semi-infinite extent,
there is a negligible amount of horizontal strain, the soil is said to
be in an at-rest state (or K0 state), and the horizontal effective
stress is:
h K0v
Where K0=coefficient of earth pressure at rest .
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The resultant thrust is equal to the area of the pressure distribution diagram, I.e.
第一节 概述 Introduction
Types of earth pressure?
主动土压力 Active earth pressure: The wall moves away from the supported
soil, and the horizontal soil pressures are refereed to as active pressure. The soil is in active state.
A uniform
Surcharge
surcharge load (q) is applied over therH 2K a/2+qH K a H
Pa
Pressure distribution
1 z q 3
S u rc h a rg e
qKa rHKa
主动土压力 Active earth pressure 被动土压力 Passive earth pressure 静止土压力 Earth pressure at rest
A ctive p re s s u re
A t-rest p re s s u re
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P a ssive p re s s u re
Soil in state of plastic equilibrium
1 z 3
Pa=rH 2K a/2
H Pa
H /3
Smooth vertical back, horizontal surface
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pa=rH Ka
3pazt2(g 45 2)zK a
Ka is coefficient of active earth pressure