地基基础检测 技术 Theoretical knowledge of deep plate load tests for foundation testing technology-深层 平板载荷试验理论知05课件讲解

地基基础检测技术深层平板载荷试验理论知识

Theoreticalknowledgeofdeepplateloadtestsforfoundationtestingtechnology深层平板载荷试验

Deepplateloadtest010101深层平板载荷试验

Deepplateloadtest1.适用范围

1.ScopeofApplication深层平板载荷试验

Deepplateloadtest深层平板载荷试验适用于确定深部地基土层及大直径桩桩端土层在承压板下应力主要影响范围内的承载力和变形参数。

Thedeepplateloadtestissuitablefordeterminingthebearingcapacityanddeformationparametersofthedeepfoundationsoillayerandthesoillayerattheendofthelarge-diameterpilewithinthemainstressinfluenceunderthebearingplate.深层平板载荷试验

Deepplateloadtest试验深度不应小于5m

Thetestdepthshallnotbelessthan5m1.适用范围

1.ScopeofApplication深层地基土

Deepfoundationsoil大直径桩的桩端土

Thesoilattheendofthelarge-diameterpile深层平板载荷试验

Deepplateloadtest2.数量要求

2.Quantityrequirement①单位工程检测数量为每500㎡不应少于1点，且总点数不应少于3点；②复杂场地或重要建筑地基应增加检测数量。

①Thetestquantityofunitworksshallnotbelessthan1pointper500m2,andthetotalnumberofpointsshallnotbelessthan3;②Thetestquantityshallbeincreasedforfoundationsofcomplexsitesorimportantbuildings.深层平板载荷试验

Deepplateloadtest3.仪器设备

3.Instrumentsandequipment试验仪器设备性能指标应符合下列规定：

Theperformanceindicatorsofthetestinstrumentsandequipmentshallmeetthefollowingrequirements:压力传感器的测量误差不应大于1%，压力表精度应优于或等于0.4级；

Themeasurementerrorofthepressuresensorshallnotbegreaterthan1%,andtheaccuracyofthepressuregaugeshallbebetterthanorequaltograde0.4;试验用千斤顶、油泵、油管在最大试验荷载时的压力不应超过规定工作压力的80%。

Thepressureofjack,oilpumpandoilpipefortestundermaximumtestloadshallnotexceed80%ofthespecifiedworkingpressure.深层平板载荷试验

Deepplateloadtest3.仪器设备

3.Instrumentsandequipment试验仪器设备性能指标应符合下列规定：

Theperformanceindicatorsofthetestinstrumentsandequipmentshallmeetthefollowingrequirements:荷重传感器、千斤顶、压力表或压力传感器的量程不应大于最大加载量的3.0倍,且不应小于最大加载量的1.2倍；

Therangeofloadsensor,jack,pressuregaugeorpressuresensorshallnotbegreaterthan3.0timesofthemaximumloadingcapacityandshallnotbelessthan1.2timesofthemaximumloadingcapacity;位移测量仪表的测量误差不应大于0.1%FS，分辨力应优于或等于0.01mm。

Themeasurementerrorofdisplacementmeasuringinstrumentshallnotbegreaterthan0.1%offullscale,andtheresolutionshallbebetterthanorequalto0.01mm.深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints（1）场地处理

(1)Sitetreatment试井直径宜等于承压板直径,当试井直径需要大于承压板直径时,紧靠承压板周围土的高度不应小于承压板直径。

Thediameterofthewelltestshallbeequaltothediameterofthebearingplate.Whenthediameterofthewelltestneedstobegreaterthanthediameterofthebearingplate,theheightofthesoilimmediatelyaroundthebearingplateshallnotbelessthanthediameterofthebearingplate.深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints当试井直径需要大于承压板直径时,紧靠承压板周围土的高度不应小于承压板直径,这是为什么?

Whenthediameterofthewelltestneedstobegreaterthanthediameterofthebearingplate,theheightofthesoilimmediatelyaroundthebearingplateshallnotbelessthanthediameterofthebearingplate.Whyisthis?以尽量保持半无限体内部的受力状态,避免试验时土的挤出。

Soastokeepthestressstateinsidethesemi-infinitebodyasmuchaspossibleandavoidsoilextrusionduringtest.深层平板载荷试验

Deepplateloadtest试井截面应为圆形,直径宜取0.8m～1.2m:并有安全防护措施

Thesectionofthewelltestshallbecircular,andthediametershallbe0.8m~1.2m,withsafetyprotectionmeasures4.试验要点

4.Testpoints深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints承压板直径不应小于0.8m,应具有足够的强度和刚度。

Thediameterofthebearingplateshallnotbelessthan0.8mandshallbeofsufficientstrengthandstiffness.(2)承压板面积

(2)Areaofbearingplate深层平板载荷试验

Deepplateloadtest可直接在外径为800mm的钢环或钢筋混凝土管柱内浇筑

Canbecastdirectlyinasteelringwithanouterdiameterof800mmorinareinforcedconcretepipecolumn

4.试验要点

4.Testpoints承压板直径取800mm时，采用厚约300mm的现浇混凝土板或预制的刚性板

Whenthediameterofbearingplateis800mm,cast-in-placeconcreteslaborprecastrigidslabwithathicknessofabout300mmisadopted深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints承压板直径不应小于0.8m,应具有足够的强度和刚度。

Thediameterofthebearingplateshallnotbelessthan0.8mandshallbeofsufficientstrengthandstiffness.(3)加载反力装置

(3)Loadingreactiondevice传力柱应有足够的刚度

Theforcetransmissioncolumnshallbeofsufficientstiffness传力柱宜高出地面50cm

Theforcetransmissioncolumnshallbe50cmabovetheground深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints(3)加载反力装置

(3)Loadingreactiondevice传力柱宜与承压板连接成为整体

Theforcetransmissioncolumnshallbeconnectedwiththebearingplateasawhole传力柱的顶部可采用钢筋等斜拉杆固定

Thetopoftheforcetransmissioncolumncanbefixedwithdiagonaltierodssuchassteelbars深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints用力柱与地面的加荷装置连接,亦可利用井壁护圈作为反力,加荷试验时应直接测读承压板的沉降。

Theforcecolumnisconnectedwiththeloadingdeviceontheground,andtheshaftwallretainercanalsobeusedforreaction.Duringtheloadingtest,thesettlementofthebearingplateshallbedirectlymeasuredandread.深层平板载荷试验

Deepplateloadtest传力柱

Forcetransmissioncolumn位移测量杆

Displacementmeasuringrod4.试验要点

4.Testpoints位移传递装置宜采用钢管或塑料管做位移测量杆

Steelpipeorplasticpipeshallbeusedasdisplacementmeasuringrodfordisplacementtransmissiondevice(4)沉降测量

(4)Settlementmeasurement深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints(4)沉降测量

(4)Settlementmeasurement位移测量杆的底端应与承压板固定连接

Thebottomofthedisplacementmeasuringrodshallbefixedlyconnectedwiththebearingplate深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints(4)沉降测量

(4)Settlementmeasurement位移测量杆宜每间隔一定距离与传力柱滑动相连

Displacementmeasuringrodisconnectedwiththeforcetransmissioncolumnbyslidingatcertaindistance深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints(4)沉降测量

(4)Settlementmeasurement位移测量杆的顶部宜高出孔口地面20cm

Thetopofthedisplacementmeasuringrodshallbe20cmabovethegroundoftheorifice深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints预压荷载：宜为最大加载量的5%

Preloadingload:5%ofthemaximumloadingcapacity预压时间：宜为5min

Preloadingtime:5min一切正常

EverythingisOK卸载至零

Unloadingtozero记录位移测试仪表初始读数

Recordtheinitialreadingofthedisplacementmeasuringinstrument读数稳定

Stablereading(5)

预压

(5)Preloading预

压

Preloading正式加载

Formalloading深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints地基土平板载荷试验的分级载荷宜为最大试验载荷的1/8~1/12。

Thesteploadoftheplateloadtestoffoundationsoilshallbe1/8~1/12ofthemaximumtestload.最大加载量不应小于设计要求的2倍。

Themaximumloadingcapacityshallnotbelessthan2timesofthedesignrequirements.(6)加卸载

(6)Loadingandunloading主要出于安全系数的考虑,一般取土层地基安全系数K=2

Consideringthesafetyfactor,thesafetyfactorofsoilfoundationisgenerallytakentobeK=2深层平板载荷试验

Deepplateloadtest(6)

加卸载

(6)Loadingandunloading第一级荷载可取分级荷载的2倍

Theloadoffirststepcanbetwicethestepload每级卸载量为分级荷载的2倍;当加载等级为奇数级时,第一级卸载量宜取分级荷载的3倍

Eachstepofunloadshallbe2timesthestepload;whentheloadinglevelisodd,theunloadingamountoffirststepshallbe3timesofthestepload加、卸载时应使荷载传递均匀、连续、无冲击,每级荷载在维持过程中的变化幅度不得超过分级荷载的±10%

Duringloadingandunloading,theloadshouldbetransmitteduniformly,continuouslyandwithoutimpact.Thevariationofloadofeachstepduringthemaintenanceprocessshallnotexceed±10%ofthestepload4.试验要点

4.Testpoints逐级等量加载

Equivalentloadingstep-by-step逐级等量加载

Equivalentloadingstep-by-step深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints每级加载后应按第10min、20min、30min、45min、60min测读承压板的沉降量,以后应每隔半小时测读一次沉降量。

Aftereachstepofloading,thesettlementofthebearingplateshallbemeasuredandreadat10min,20min,30min,45minand60min,andthesettlementshallbemeasuredandreadeveryhalfanhourthereafter.当在连续两小时内,每小时的沉降量小于0.1mm时,则认为已趋稳定,可加下一级荷载。

Whenthesettlementshallbelessthan0.1mmperhourwithintwoconsecutivehours,itisconsideredtobestableandtheloadofnextstepcanbeapplied.(6)加卸载

(6)Loadingandunloading深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints卸载时，每级荷载维持1h，应按第10min、30min、60min测读承压板沉降量；卸载至零后，应测读承压板残余沉降量,维持时间为3h，测读时间应为第10min、30min、60min、120min、180min。

Duringunloading,theloadateachstepshallbemaintainedfor1h,andthesettlementofthebearingplateshallbemeasuredandreadat10min,30minand60min;Afterunloadingtozero,theresidualsettlementofthebearingplateshallbemeasuredandread,andtheholdingtimeis3h,andthemeasuringandreadingtimeshallbe10min,30min,60min,120minand180min.(6)加卸载

(6)Loadingandunloading深层平板载荷试验

Deepplateloadtest4.试验要点

4.Testpoints当出现下列情况之一时,即可终止加载:

Loadingcanbeterminatedwhenoneofthefollowingconditionsoccurs:①本级荷载的沉降量大于前级荷载沉降量的5倍，荷载-沉降(p-s)曲线出现明显陡降；

①Thesettlementoftheloadatthislevelisgreaterthan5timesthesettlementoftheprevi