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时间:2019-05-13
《应变软化模拟与圆形隧道衬砌分析》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、第31卷第6期岩土力学Vol.31No.62010年6月RockandSoilMechanicsJun.2010文章编号:1000-7598(2010)06-1929-08应变软化模拟与圆形隧道衬砌分析王水林,吴振君,李春光,汤华(中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,武汉430071)摘要:在岩土工程中,有许多类岩体呈现应变软化特性。在应变软化过程中,如果多个材料强度参数分析发生变化,就很难给出软化问题的解析解。已有的文献研究表明,在经典的弹塑性理论框架下,模拟岩土介质的应变软化过程依
2、然值得深入研究。利用应变软化材料强度参数随塑性应变增加而弱化的特点,提出了将应变软化过程简化为一系列的脆性应力跌落与塑性流动过程的思想,应变软化行为的模拟转化为一系列脆塑性过程的分析。将这种模拟应变软化过程的思想方法用于求解均匀初始应力场中应变软化介质内的圆形隧道开挖问题,研究了衬砌对减少岩土开挖扰动的作用以及考虑应变软化对衬砌内力的影响。数值结果表明,对于应变软化岩土材料,忽略其强度软化的行为是偏于危险的。关键词:应变软化;脆塑性模型;圆形隧道;数值解;屈服准则中图分类号:U452文献标识码:AModel
3、ingofstrain-softeningandanalysisofaliningforcirculartunnelWANGShui-lin,WUZhen-jun,LIChun-guang,TANGHua(StateKeyLaboratoryofGeomechanicsandGeotechnicalEngineering,InstituteofRockandSoilMechanics,ChineseAcademyofSciences,Wuhan430071,China)Abstract:Ingeotechn
4、icalengineering,manytypesofrockmassesbehaveinastrain-softeningway.Itisnoteasytogettheclosedformsolutionwhenstrengthparameterschangeinthestrain-softeningprocess.Literaturereviewshowsthatthestrain-softeningproblemhasnotbeensufficientlyanalyzedwithintheframew
5、orkoftheclassicaltheoryofelastoplasticity.Basedonthecharacteristicsofstrain-softeningmaterialinwhichthestrengthparameterschangewhiletheplasticstrainincreases,anewmethodforsolvingstrain-softeningproblemsisproposed.Intheproposednumericalscheme,stress-strainc
6、urveinthestrain-softeningstageisapproximatedinastepwiseway;andtheprocessesofthestrain-softeningissimplifiedasaseriesofstressdropandplasticflowduringtheincreaseofplasticstrain.Therefore,modelingastrain-softeningproblembecomesaseriesofbrittle-plasticanalysis
7、.Theapproachisemployedtoexaminethecircularopeningexcavationinahomogeneousandisotropicrockmasssubjectedtoahydrostaticinsitustress.Theeffectofliningontheplasticregionanddeformationinthesurroundingrockmassisanalyzed;andtheinfluenceofstrain-softeningbehaviouri
8、salsodiscussed.Numericalresultsindicatethatitisunsafetoignorethestrengthdecreasewhentunnelexcavationandlinerinstallationarecarriedoutinthestrain-softeningrockmass.Keywords:strain-softening;brittle-plasticmode
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