复合地基的减振模型及算例
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摘要
复合地基的减振性能主要体现在减小振幅、黏滞阻尼耗能和摩擦耗能上·根据复合地基的减振机理,可把基础和垫层简化为多自由度质、阻、弹振动体系,同时考虑滑动摩擦作用·基于上述简化,建立了复合地基的减振模型和体系的动力方程,并编制利用Wilson θ法求解的相应计算程序·算例表明,由于复合地基设置了褥垫层,其层间最大位移比桩基的要小得多,滑动反应谱峰值也有显著削弱,显示了明显的减振效果·
The shock absorption capacity of composite foundation plays mainly the roles of amplitude reduction, viscous damping for energy consumption and friction energy consumption. Based on the composite foundation's shock absorption mechanism, the foundation and cushion can be simplified to be a vibrating system involving mass, damping and elasticity with multiple degrees of freedom, of which the frictional action is also taken into account. Then, a shock absorption model and dynamic equation are developed, with a program given using wilson-θ method to compute the equation. A calculating example shows that the maximum interbedded displacement due to composite foundation and cushion is much less than that due to pile foundation. In addition, the maximum value of sliding response spectrum also decreases. All these reveals that the effect of shock absorption is obvious.
The shock absorption capacity of composite foundation plays mainly the roles of amplitude reduction, viscous damping for energy consumption and friction energy consumption. Based on the composite foundation's shock absorption mechanism, the foundation and cushion can be simplified to be a vibrating system involving mass, damping and elasticity with multiple degrees of freedom, of which the frictional action is also taken into account. Then, a shock absorption model and dynamic equation are developed, with a program given using wilson-θ method to compute the equation. A calculating example shows that the maximum interbedded displacement due to composite foundation and cushion is much less than that due to pile foundation. In addition, the maximum value of sliding response spectrum also decreases. All these reveals that the effect of shock absorption is obvious.
引文
[1]王凤池,朱浮声·复合地基的褥垫层设计[J]·东北大学学报(自然科学版),2004,25(3):287-290·(WangFC,ZhuFS.Cushiondesigningofcompositefoundation[J].JournalofNortheasternUniversity(NaturalScience).2004,25(3):287-290.)
[2]BarcanDD,MegevoyGN.Investigationofpilefoundationwithintermediatecushionforseismicregions[J].RoorkeeIndia,1973,9(5):201-210.
[3]HugesJMO,WithersNJ.Reinforcingsoftcohesivesoilswithstonecolumns[J].GroundEngineering,1974,7(3):42-49.
[4]BouassidaM.Bearingcapacityofafoundationrestingonasoilreinforcedbyagroupofcolumns[J].Geotechnique,1995,45(1):25-34.
[5]RathmayerHG,SaariKHO.vanImpeWF,etal.Improvementofsettlementbehaviourofsoftlayersbymeansofstonecolumns[A].Procof8thEuropeanConferenceonSoilMechanicsandFoundationEngineering:ImprovementofGround[C].Rotterdam:Balkema,1983.309-312.
[6]吴春林,闫明礼·CFG桩及其复合地基水平荷载作用下的性状[J]·工程勘察,1996,(4):18-21·(WuCL,YanML.BehaviorofCFGpileanditscompositefoundationunderhorizontalloading[J].GeotechnicalInvestigationandSurveying,1996,(4):18-21.)
[7]WolfJP,ObernhuberP.Effectsofhorizontallypropagatingwavesontheresponseofstructurewithasoftfirststorey[J].EarthquakeEngineeringandStructureDynamic,1981,9(1):1-21.
[8]KellyM.Aseismicbaseisolation:reviewandbibliography[J].SDEE,1986,15(3):202-305.
[9]GinaJL,GoodarzA,LucasGH.Integratedpassive/activevibrationabsorbedformulti storybuilding[M].Hamptom:NASALangleyResearchCenter,1995.4-8.
[10]杨庆,栾茂田·混凝土底板与碎石垫层室内水平抗滑试验研究[J]·工程勘察,1999,(6):5-8·(YangQ,LuanMT.Indoormodeltestofshearslidingbetweenconcreteboardandsoilcushion[J].GeotechnicalInvestigationandSurveying,1999,(6):5-8.)
[11]乔太平,刘惠珊·地基与工业建筑抗震[M]·北京:地震出版社,1984.290-319·(QiaoTP,LiuHS.Anti earthquakeoffoundationandindustrybuilding[M].Beijing:SeismicPress,1984.290-319.)
[2]BarcanDD,MegevoyGN.Investigationofpilefoundationwithintermediatecushionforseismicregions[J].RoorkeeIndia,1973,9(5):201-210.
[3]HugesJMO,WithersNJ.Reinforcingsoftcohesivesoilswithstonecolumns[J].GroundEngineering,1974,7(3):42-49.
[4]BouassidaM.Bearingcapacityofafoundationrestingonasoilreinforcedbyagroupofcolumns[J].Geotechnique,1995,45(1):25-34.
[5]RathmayerHG,SaariKHO.vanImpeWF,etal.Improvementofsettlementbehaviourofsoftlayersbymeansofstonecolumns[A].Procof8thEuropeanConferenceonSoilMechanicsandFoundationEngineering:ImprovementofGround[C].Rotterdam:Balkema,1983.309-312.
[6]吴春林,闫明礼·CFG桩及其复合地基水平荷载作用下的性状[J]·工程勘察,1996,(4):18-21·(WuCL,YanML.BehaviorofCFGpileanditscompositefoundationunderhorizontalloading[J].GeotechnicalInvestigationandSurveying,1996,(4):18-21.)
[7]WolfJP,ObernhuberP.Effectsofhorizontallypropagatingwavesontheresponseofstructurewithasoftfirststorey[J].EarthquakeEngineeringandStructureDynamic,1981,9(1):1-21.
[8]KellyM.Aseismicbaseisolation:reviewandbibliography[J].SDEE,1986,15(3):202-305.
[9]GinaJL,GoodarzA,LucasGH.Integratedpassive/activevibrationabsorbedformulti storybuilding[M].Hamptom:NASALangleyResearchCenter,1995.4-8.
[10]杨庆,栾茂田·混凝土底板与碎石垫层室内水平抗滑试验研究[J]·工程勘察,1999,(6):5-8·(YangQ,LuanMT.Indoormodeltestofshearslidingbetweenconcreteboardandsoilcushion[J].GeotechnicalInvestigationandSurveying,1999,(6):5-8.)
[11]乔太平,刘惠珊·地基与工业建筑抗震[M]·北京:地震出版社,1984.290-319·(QiaoTP,LiuHS.Anti earthquakeoffoundationandindustrybuilding[M].Beijing:SeismicPress,1984.290-319.)
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