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1、岩土工程研究所第六章 土压力河海大学 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 概述 Introductionn土压力概念 What is earth pressure?n土压力种类： Types of earth pressuren静止土压力： Earth pressure at rest岩土工程研究所What is earth pressure?第一节 概述 IntroductionEarth pressure: The
2、pressure applied on a retaining wall from soil 岩土工程研究所第一节 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 restTypes of earth pressure?岩土工程研究所第一节 概述 Introduction主动土压力 Active earth pressure: The wall moves away from the supported soil, and the horizontal s
3、oil 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
4、 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:
5、plastic equilibrium with lateral compression taking place.静止平衡状态: At-rest state: elastic equilibrium with no lateral strain taking place.岩土工程研究所第一节 概述 IntroductionUnder natural conditions of deposition, with semi-infinite extent, there is a negligible amount of horizontal strain, the soil is said to
6、 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. 岩土工程研究所第二节 朗肯土压力理论 Rankines theory Active earth pressure in cohes
7、ionless soils Smooth vertical back, horizontal surfaceThe wall moves away from the earthfill, Vertical stress is major principal stress Soil in state of plastic equilibriumKa is coefficient of active earth pressure岩土工程研究所第二节 朗肯土压力理论 Rankines theory Active earth pressure in cohesionless soils Pressur
8、e distributionA uniform surcharge load (q) is applied over the whole surfaceThe wall moves away from the earthfill, Vertical stress is major principal stress 岩土工程研究所第二节 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 distr
9、ibution 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, 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/3Kp is coefficien
10、t of passive earth pressurePassive earth pressure岩土工程研究所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 pressureThe resultant thrust is equal to the area of the pressure distribution diagram The line
11、 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 朗肯土压力理论 Rankines theory Active earth pressure in cohesive soils Assuming: Tension crack depth: Total passive resistance force: 岩土工程研究所第二节 朗肯土压力理论 Rankines theory Active earth pressure in cohesive s
12、oils Assuming: Tension crack depth: (c)(d)If Z00, then case (c); 岩土工程研究所第二节 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); PaPa岩土工程研究所第二节 朗肯土压力理论 Rankines theory Passive earth pressure in cohesive soils 岩土工程研究所第二节 朗肯土压力理论 Rankines
13、theory Passive earth pressure in cohesive soils 岩土工程研究所Active earth pressure in case of ground water 第二节 朗肯土压力理论 Rankines theoryThe resultant horizontal thrust: 岩土工程研究所第二节 朗肯土压力理论 Rankines theory Active earth pressure in stratified soil1 2Layer 1Layer 2岩土工程研究所谢谢！ Thank You !-结束结束 The ENDThe END-岩土工程
14、研究所总结 SummarynToday, 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.
