公路隧道二次衬砌合理支护时机研究

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1、密级公开分类号U455工程硕士学位论文公路隧道二次衬砌合理支护时机研究向海辉指导教师李宝平教授许浩高级工程师申请学位级别工程硕士工程领域建筑与土木工程2018年5月11日内，受力分布与茶镇隧道测线布置位置基本相符，计算模型具有可靠性，隧道在开挖至第26天时，可以开始施做二衬。(4)采用添加不同围岩荷载释放系数的方法，选取多种不同工况，研究初次衬砌与二次衬砌在承担不同比例荷载的情况下对隧道拱顶沉降与洞身收敛值、围岩与支护结构的应力变化规律的影响，通过对不同荷载释放系数及二衬分配比例的工况进行分析，确定了荷载释放系数为60%、二衬承担15%荷载比例时为合理的支

2、护时机。关键词：软弱围岩；支护时机；二次衬砌；数值模拟；监控量测overalltrendofthethreemeasuredsectionsisfastincreasingandthengraduallyslowingdownuntilfinallytendstorelativelystable.Onthebasisofsecondaryliningsupporttimediscriminationmethodandprincipleofcomparativeanalysistodeterminethereasonabletimeoftheexcavati

3、ontoabout24~26days,fromthefaceof48~52m.(3)Determinethecalculationrangeandboundaryconditions,establishthecorrespondingengineeringmodel,usingMIDASGTStosimulatethetunnelmodel,analysisofthechangeregularityoftunnelvaultsettlement,tunnelconvergence,thestressofthelining,andtheresultsofth

4、esimulationandmonitoringmeasurementdatawerecomparedandanalyzed,theresultsshowedthatthemonitoringdataandtheresultsofcalculationerrorinareasonablerange,andthestressdistributionofCha-Zhentunnellinelayoutpositionconsistentwiththereliabilitycalculationmodeloftunnelexcavationintwenty-si

5、xthdays,canbegintodothesecondarylining.(4)byaddingdifferentsurroundingrockloadreleasecoefficientmethod,wechoosemultipleworkingconditionstostudytheinfluenceofinitialliningandsecondaryliningonthestressandvariationoftunnelvaultsettlementandtunnelconvergencevalueandsurroundingrockands

6、upportingstructureunderdifferentloadproportions.Then,theworkingconditionsofdifferentloadreleasecoefficientsandtheproportionofthesecondaryliningdistributionareanalyzed,andthereasonablesupporttimeisdeterminedwhentheloadreleasecoefficientis60%andthesecondaryliningbears15%loadratio.Ke

7、yWords:weaksurroundingrock;supportingtime;secondarylining;numericalsimulation;monitoringmeasurement目录1绪论........................................................................................................................................11.1研究背景及其意义.............................

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