土的压缩与固结 英文版.ppt

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1、CompressibilityandConsolidationofSoil(土的压缩与固结)Inthislecture,we’lllearnDifferencebetweenconsolidation(固结)andcompaction(压实)One-dimensionalconsolidationtest(单向固结试验)Normalandoverconsolidatedsoils(正常与超固结土)，Pre-consolidationpressure(前期固结压力)，Overconsolidatio

2、nratio(超固结比)Immediatesettlement(瞬时沉降)，Primaryconsolidation(主固结沉降)，Secondaryconsolidation(次固结沉降）Terzaghi’sone-dimensionalconsolidationtheory(太沙基-单向固结理论)CompactionVsConsolidation(压实与固结的比较)Whatisthedifferencebetweencompactionandconsolidation?压实与固结有什么的分别?

3、CompactionVsConsolidation(压实与固结的比较)空气的体积减小孔隙水的体积减小Whatisconsolidation?(什么是固结?)Consolidationisatime-related(时间性)processofincreasingthedensity(增加密度)ofbydrainingsomeofthewateroutofthevoids.Coarse-grainedsoils(粗粒土),suchassandsandgravels,consolidateatamuc

4、hfasterratethanfine-grainedsoils(幼粒土)suchassiltsandclays.Theneedofconsolidationtheory(固结理论的重要性)TiltingofPizaTowerisduetodifferentialsettlement(不平均沉降引起塔的倾斜)Twoimportantquestionsforconsolidationproblems(两个重要问题)Howmuch?(沉降有多少)Howlong?(时间有多久)PizaTower,It

5、alyconsolidationtest(单向固结试验)Consolidationisathree-dimensional(三维)process,butthedirectionofflowofwaterisprimarilyvertical(主要在竖向)orone-dimensional(1-D).s’zvz(waterflow)vxvys’zvzSimplify简单化consolidationtest(单向固结试验)土样本(竖向荷载)侧向应变为零Verticalsettlement(竖向沉降)O

6、edometer(固结仪)Load–settlementcurveor1-Dcompressioncurve(单向压缩曲线)(水缸)Time–relatedconsolidation(固结与时间关系)Foreachloadincrement(每一个荷载增量)hf’fEffectofstresshistory(应力历史)whereOCRisoverconsolidationratio(超固结比),’viscurrenteffectivestress(现今有效应力)and’vmaxisma

7、ximumpasteffectivestress(过去最大有效应力)orpre-consolidationpressure[’c](前期固结压力)OCR=1Normallyconsolidated[NC]soil(正常固结土)OCR>1Overconsolidated[OC]soil(超固结土)过去最大有效应力过去最大有效应力Settlement(沉降)Settlementfoundinsoilduetoloadingmaybedividedintothreecategories:（在土壤中沉降

8、分为三部分）whereStistotalsettlement(总沉降),Siisimmediatesettlement(瞬时沉降)–[elasticdeformation,弹性变形],Scisprimaryconsolidation(主固结沉降)–[changeof’,有效应力改变]andSsissecondaryconsolidation(次固结沉降)–[time,时间]immediatesettlement(瞬时沉降)primaryconsolidation(主固结沉降)se