土压力河海大学岩土工程研究所.ppt
第六章 土压力,河海大学 岩土工程研究所Research Institute of Geotechnical Engineering,Hohai University,Chapter 6 Earth Pressure,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,What is earth pressure?,第一节 概述 Introduction,Earth pressure:The pressure applied on a retaining wall from soil,第一节 概述 Introduction,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,Types of earth pressure?,第一节 概述 Introduction,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.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.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 be at-rest pressure.The soil is in at-rest state.,Types of earth pressure?,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.,第一节 概述 Introduction,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:,Where K0=coefficient of earth pressure at rest.,At-rest earth pressure?,The resultant thrust is equal to the area of the pressure distribution diagram,I.e.,第二节 朗肯土压力理论Rankines theory,Active earth pressure in cohesionless soils,Smooth vertical back,horizontal surface,The wall moves away from the earthfill,Vertical stress is major principal stress,Soil in state of plastic equilibrium,Ka is coefficient of active earth pressure,第二节 朗肯土压力理论Rankines theory,Active earth pressure in cohesionless soils,Pressure distribution,A uniform surcharge load(q)is applied over the whole surface,The wall moves away from the earthfill,Vertical stress is major principal stress,第二节 朗肯土压力理论Rankines theory,Active earth pressure in cohesionless soils,The resultant thrust is equal to the area of the pressure distribution diagram,I.e.the area of trapezia,The line of action of Pa passes through the center of the area of the trapezia,The wall moves towards the earthfill,Vertical stress is minor principal stress,第二节 朗肯土压力理论Rankines theory,Passive earth pressure in cohesionless soils,H/3,Kp is coefficient of passive earth pressure,Passive earth pressure,Vertical stress is minor principal stress,第二节 朗肯土压力理论Rankines theory,Passive earth pressure in cohesionless soils,Kp is coefficient of passive earth pressure,The resultant thrust is equal to the area of the pressure distribution diagram,The line of action of Pp passes through the center of the area of the pressure distribution diagram,第二节 朗肯土压力理论Rankines theory,Active earth pressure in cohesive soils,Assuming:,Tension crack depth:,Total passive resistance force:,第二节 朗肯土压力理论Rankines theory,Active earth pressure in cohesive soils,Assuming:,Tension crack depth:,(c),(d),If Z00,then case(c);,第二节 朗肯土压力理论Rankines theory,Active earth pressure in cohesive soils,(c),(d),If Z00,then case(c);,If Z00,then case(d);,Pa,Pa,第二节 朗肯土压力理论Rankines theory,Passive earth pressure in cohesive soils,第二节 朗肯土压力理论Rankines theory,Passive earth pressure in cohesive soils,Active earth pressure in case of ground water,第二节 朗肯土压力理论Rankines theory,The resultant horizontal thrust:,第二节 朗肯土压力理论Rankines theory,Active earth pressure in stratified soil,1,2,Layer 1,Layer 2,谢谢！Thank You!,-结束 The END-,欢迎提出意见或建议,总结 Summary,Today,in the following hours I am going to introduce chapter 6 using English.My spoken English is not so good.This is the first time that I have had a class in English.It is really a challenging task for both you and me.I am not sure whether I can success,but I will do my best to make you understand what I mean.I hope all of you support me.,
