土力学课件第六章土压力.ppt

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1、岩土工程研究所第六章第六章 土压力土压力河海大学河海大学 岩土工程研究所岩土工程研究所Research Institute of Geotechnical Engineering,Hohai UniversityChapter 6 Earth Pressure岩土工程研究所第一节第一节 概述概述 IntroductionIntroductionn n土压力概念土压力概念土压力概念土压力概念 What is earth pressure?What is earth pressure?n n土压力种类：土压力种类：土压力种类：土压力种类：Types of earth pressureTypes o

2、f earth pressuren n静止土压力：静止土压力：静止土压力：静止土压力：Earth pressure at restEarth pressure at rest岩土工程研究所n nWhat is earth pressure?What is earth pressure?第一节第一节 概述概述 IntroductionIntroductionEarth pressure:Earth pressure:The pressure applied on The pressure applied on a retaining wall from soil a retaining wall

3、 from soil 岩土工程研究所第一节第一节 概述概述 IntroductionIntroduction主动土压力主动土压力主动土压力主动土压力 Active earth pressureActive earth pressure被动土压力被动土压力被动土压力被动土压力 Passive earth pressurePassive earth pressure静止土压力静止土压力静止土压力静止土压力 Earth pressure at restEarth pressure at restn nTypes of earth pressure?Types of earth pressure?岩土

4、工程研究所第一节第一节 概述概述 IntroductionIntroduction主动土压力主动土压力主动土压力主动土压力 Active earth pressure:Active earth pressure:The wall moves away from the supported The wall moves away from the supported soil,and the horizontal soil pressures are refereed to assoil,and the horizontal soil pressures are refereed to as a

5、ctive pressure.active pressure.The soil is in active state.The soil is in active state.被动土压力被动土压力被动土压力被动土压力 Passive earth pressure:Passive earth pressure:The wall is caused to move towards the The wall is caused to move towards the soil being supported,soil being supported,and the horizontal soil pr

6、essures are refereed to asand the horizontal soil pressures are refereed to as passive pressure.passive pressure.The soil is in passive state.The soil is in passive state.静止土压力静止土压力静止土压力静止土压力 Earth pressure at rest:Earth pressure at rest:The wall is rigid and does not yield,that is The wall is rigid

7、 and does not yield,that is there is no movement taking place,the horizontal soil pressures are said to there is no movement taking place,the horizontal soil pressures are said to bebe at-rest pressureat-rest pressure.The soil is in at-rest state.The soil is in at-rest state.n nTypes of earth pressu

8、re?Types of earth pressure?主动极限平衡状态主动极限平衡状态主动极限平衡状态主动极限平衡状态:Active state:Active state:plastic equilibrium with lateral expansion taking place.plastic equilibrium with lateral expansion taking place.被动被动被动被动极限平衡状态极限平衡状态极限平衡状态极限平衡状态:Passive state:Passive state:plastic equilibrium with lateral compress

9、ion taking place.plastic equilibrium with lateral compression taking place.静止平衡状态静止平衡状态静止平衡状态静止平衡状态:At-rest state:At-rest state:elastic equilibrium with no lateral strain taking place.elastic equilibrium with no lateral strain taking place.岩土工程研究所第一节第一节 概述概述 IntroductionIntroductionUnder natural con

10、ditions 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.n nAt-rest earth pressure?At-rest earth pressure?The resulta

11、nt thrust is equal to the area of the pressure distribution diagram,I.e.岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theory Rankines theory n nActive earth pressure Active earth pressure in cohesionless soilsin cohesionless soils Smooth vertical back,Smooth vertical back,horizontal surfacehorizontal surface

12、 The wall moves away from the earthfill,The wall moves away from the earthfill,Vertical stress is major principal stress Vertical stress is major principal stress Soil in state of Soil in state of plastic equilibriumplastic equilibriumKa is coefficient of active earth pressureKa is coefficient of ac

13、tive earth pressure岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theoryRankines theoryn nActive earth pressure Active earth pressure in cohesionless soilsin cohesionless soils Pressure distributionA uniform A uniform surcharge load surcharge load(q)is applied(q)is applied over the whole over the whole surfac

14、esurface The wall moves away from the earthfill,The wall moves away from the earthfill,Vertical stress is major principal stress Vertical stress is major principal stress 岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theoryRankines theoryn nActive earth pressure Active earth pressure in cohesionless soilsin

15、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 岩土工程研究所 The wall moves towards the earthfill,The wall moves towards the earthfill,Vertical stress

16、is minor principal stress 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 theoryRankines theoryn nPassive earth pressure Passive earth pressure in cohesionless soilsin cohesionless soils H/3K Kp p is coefficient of is coefficient of passive earth passive earth pressurepressure

17、Passive earth pressure岩土工程研究所 Vertical stress is minor principal stressVertical 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 theoryRankines theoryn nPassive earth pressure Passive earth pressure in cohesionless soilsin cohesionless soils K Kp p is is coefficient of coefficient of pa

18、ssive earth passive earth pressurepressureThe 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 岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theoryRankines theoryn nActive earth press

19、ure Active earth pressure in cohesive soilsin cohesive soils Assuming:Tension crack depth:Total passive resistance force:岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theoryRankines theoryn nActive earth pressure Active earth pressure in cohesive soilsin cohesive soils Assuming:Tension crack depth:(c)(d)If Z

20、00,then case(c);岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theoryRankines theoryn nActive earth pressure Active earth pressure in cohesive soilsin cohesive soils (c)(d)If Z00,then case(c);If Z00,then case(d);PaPa岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theoryRankines theoryn nPassive earth pressure Passive ea

21、rth pressure in cohesive soilsin cohesive soils 岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theoryRankines theoryn nPassive earth pressure Passive earth pressure in cohesive soilsin cohesive soils 岩土工程研究所n nActive earth pressure Active earth pressure in case of ground water in case of ground water 第二节第二节 朗

22、肯土压力理论朗肯土压力理论Rankines theoryRankines theoryThe resultant horizontal thrust:岩土工程研究所第二节第二节 朗肯土压力理论朗肯土压力理论Rankines theoryRankines theoryn nActive earth pressure Active earth pressure in stratified soilin stratified soil12Layer 1Layer 2岩土工程研究所 谢谢谢谢！Thank You!-结束 The END-岩土工程研究所总结总结 SummarySummaryn nToda

23、y,in the following hours I am going to introduce Today,in the following hours I am going to introduce chapter 6 using English.My spoken English is not so chapter 6 using English.My spoken English is not so good.This is the first time that I have had a class in good.This is the first time that I have

24、 had a class in English.It is really a challenging task for both you and English.It is really a challenging task for both you and me.I am not sure whether I can success,but I will do me.I am not sure whether I can success,but I will do my best to make you understand what I mean.I hope my best to make you understand what I mean.I hope all of you support me.all of you support me.