土压力 土力学 岩土教研室.pptx

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1、nWhat is earth pressure?第一节 概述 IntroductionEarth pressure:Earth pressure:The pressure applied on The pressure applied on a retaining wall from soil a retaining wall from soil 第1页/共19页第一节 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 restnTypes of earth

2、 pressure?第2页/共19页第一节 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 t

3、he 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.nTypes

4、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3页/共19页第一节 概述 IntroductionUnder natural condi

5、tions 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.nAt-rest earth pressure?The resultant thrust is equal to the a

6、rea of the pressure distribution diagram,I.e.第4页/共19页第二节 朗肯土压力理论Rankines theory nActive 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 equilibriumKa is coefficient

7、of active earth pressure第5页/共19页第二节 朗肯土压力理论Rankines theorynActive earth pressure in cohesionless soils Pressure distributionA uniform surcharge load(q)is applied over the whole surface The wall moves away from the earthfill,Vertical stress is major principal stress 第6页/共19页第二节 朗肯土压力理论Rankines theory

8、nActive 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 第7页/共19页 The wall moves towards the earthfill,Vertical stress is minor p

9、rincipal stress第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theorynPassive earth pressure in cohesionless soils H/3Kp is coefficient of passive earth pressurePassive earth pressure第8页/共19页 Vertical stress is minor principal stress第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theorynPassive earth pressure in cohesionless soils Kp

10、is coefficient of passive earth pressureThe 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9页/共19页第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theorynActive earth pressure in cohesive so

11、ils Assuming:Tension crack depth:Total passive resistance force:第10页/共19页第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theorynActive earth pressure in cohesive soils Assuming:Tension crack depth:(c)(d)If Z00,then case(c);第11页/共19页第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theorynActive earth pressure in cohesive soils(c)(d)If Z

12、00,then case(c);If Z00,then case(d);PaPa第12页/共19页第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theorynPassive earth pressure in cohesive soils 第13页/共19页第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theorynPassive earth pressure in cohesive soils 第14页/共19页nActive earth pressure in case of ground water 第二节第二节 朗肯土压力理论朗肯土压力理论Rankines

13、theoryThe resultant horizontal thrust:第15页/共19页第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theorynActive earth pressure in stratified soil12Layer 1Layer 2第16页/共19页 谢谢谢谢！Thank You!-结束 The END-第17页/共19页总结 SummaryToday,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.第18页/共19页感谢您的观看。第19页/共19页