考虑超静孔隙水压力消散的管桩承载力时效性研究.pdf

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1、JournalofEngineeringGeology工程地质学报1004—9665／2012／20(5)一0815—06考虑超静孔隙水压力消散的管桩承载力时效性研究木雷华阳①②吕乾乾①刘利霞①(①天津大学土木工程系天津300072)(②滨海土木212程结构与安全教育部重点实验室(天津大学)天津300072)摘要沉桩引起的超静孔隙水压力消散是产生管桩极限承载力时效性的主要因素之一。结合天津东疆保税港区物流加工区二期工程，利用有限元模拟分析沉桩后超孔压的消散规律及管桩的极限承载力随时间变化的规律，提出吹填土中管桩时效承载力公式供工程参考

2、使用，并进行吹填土现场各测点沉桩过程及沉桩后孔隙水压力的监测，验证模拟结果的同时探讨超静孔隙水压力的分布及消散规律。模拟得到沉桩后桩底超孔压随时间消散，20d后消散率达到97％；管桩的时效承载力随时间增长，并与超孔压的消散有着明显的对应关系；得到吹填土中管桩承载力的时效公式以供工程参考使用。现场孔压监测表明深度增加，超孔压增大；离桩越近，超孔压越大；土层渗透系数越小，超孔压消散越慢。施工对土体的有效影响范围为9—10倍桩径。关键词吹填土管桩极限承载力时效性超静孔隙水压力中图分类号：Tu443文献标识码：AGRoWTHoFPILEBEA

3、RINGCAPACITYoVERTIMECoNSIDERINGTHEDISSIPATINGoFEXCESSPOREPRESSURELEIHuayang①②LVQianqian~LIULixia①(@DepartmentofCivilEngineering，TianfinUniversity，Tianfin300072)(~KeyLaboratoryofCivilStructureandSafetyofBinhai，TianfinUniversity，Tianjin300072)AbstractThedissipatingofexces

4、sporepressurecausedbypilesinkingisoneofthemainfactorsresultintimeeffectofultimatebearingcapacityofpile．Thispaperdiscussesthechangeruleofpilebearingcapacitywithtimethroughthefiniteelementsimulationunderthegeologicalconditionsofthepile~undationinthesecondphasepro—jectofth

5、efreeportlogisticsprocessingzoneinDongjiang，Tianjin．Itfindsthattheformulaofpilebeatingcapacityabouttimeeffectindredgefillcanbeusedasreferenceforengineeringuse．Itmonitorstheexcessporepressureateachobservingpointinordertoverifythenumericalsimulationresults．Itdiscussesthec

6、hangelawofthedistribu—tionanddissipationofexcessporewaterpressure．Numericalsimulationshowsthatthedissipationrateatthetipofpilecanreach97％20dafterpilesinking．Theultimatebeatingcapacityofpipepileincreasesovertimebasicallyinaccordwiththedissipationofexcessporewaterpressure

7、．Italsointroducesaformulaofpileagingbeatingcapac—ityindredgefil1．Measuredresultsshowthattheeffectiverangeofconstructionondredgerfillaroundthepileis9—10timesthediameterofpile．Theexcessporepressureincreaseswiththedepthincreasing．Thecloseritfromthepile，thegreatertheexcessp

8、orepressureis．Thesmallerthepermeabilitycoeficientofsoilis，themoreslowlytheexcessporepressuredissipates．Keyword