河海大學(xué)土力學(xué)課件chpt

1、巖土工程研究所第六章第六章 土壓力土壓力河海大學(xué)河海大學(xué) 巖土工程研究所巖土工程研究所Research Institute of Geotechnical Engineering, Hohai UniversityChapter 6 Earth Pressure巖土工程研究所第一節(jié)第一節(jié) 概述概述 Introductionn土壓力概念土壓力概念 What is earth pressure?n土壓力種類：土壓力種類： Types of earth pressuren靜止土壓力：靜止土壓力： Earth pressure at rest巖土工程研究所nWhat is earth pressure

2、?第一節(jié)第一節(jié) 概述概述 IntroductionEarth pressure: The pressure applied on a retaining wall from soil 巖土工程研究所第一節(jié)第一節(jié) 概述概述 Introduction主動(dòng)土壓力主動(dòng)土壓力 Active earth pressure被動(dòng)土壓力被動(dòng)土壓力 Passive earth pressure靜止土壓力靜止土壓力 Earth pressure at restnTypes of earth pressure?巖土工程研究所第一節(jié)第一節(jié) 概述概述 Introduction主動(dòng)土壓力主動(dòng)土壓力 Active earth

3、 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.被動(dòng)土壓力被動(dòng)土壓力 Passive earth pressure:The wall is caused to move towards the soil being supported, and the horizontal soil pressures are refereed to a

4、s passive pressure. The soil is in passive state.靜止土壓力靜止土壓力 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 of earth pressure?主動(dòng)極限平衡狀態(tài)主動(dòng)極限平衡狀態(tài): :

5、 Active state: plastic equilibrium with lateral expansion taking place.被動(dòng)被動(dòng)極限平衡狀態(tài)極限平衡狀態(tài): : Passive state: plastic equilibrium with lateral compression taking place.靜止平衡狀態(tài)靜止平衡狀態(tài): : At-rest state: elastic equilibrium with no lateral strain taking place.巖土工程研究所第一節(jié)第一節(jié) 概述概述 IntroductionUnder natural cond

6、itions 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?vhK0The resultant thrust is eq

7、ual to the area of the pressure distribution diagram, I.e. 巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論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 equi

8、libriumKa is coefficient of active earth pressure巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論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 stre

9、ss 巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theorynActive 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 巖土工程研究所 The wall moves t

10、owards the earthfill, Vertical stress is minor principal stress第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theorynPassive earth pressure in cohesionless soils H/3Kp is coefficient of passive earth pressurePassive earth pressure巖土工程研究所 Vertical stress is minor principal stress第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theorynP

11、assive 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 of action of Pp passes through the center of the area of the pressure distribution diagram 巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankin

12、es theorynActive earth pressure in cohesive soils 13Assuming: Tension crack depth: Total passive resistance force: 巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theorynActive earth pressure in cohesive soils Assuming: Tension crack depth: (c)(d)If Z00, then case (c); 巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theo

13、rynActive earth pressure in cohesive soils (c)(d)If Z00, then case (c); If Z00, then case (d); PaPa巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theorynPassive earth pressure in cohesive soils Surcharge巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theorynPassive earth pressure in cohesive soils 巖土工程研究所nActive earth p

14、ressure in case of ground water 第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theoryThe resultant horizontal thrust: 巖土工程研究所第二節(jié)第二節(jié) 朗肯土壓力理論朗肯土壓力理論Rankines theorynActive earth pressure in stratified soil12Layer 1Layer 2巖土工程研究所 -巖土工程研究所總結(jié)總結(jié) SummarynToday, in the following hours I am going to introduce chapter 6 using English. My spoken English is not so good. This is the f