复杂地质条件下隧道支护体时效可靠性分析

由于隧道围岩具有蠕变特性，导致隧道结构的可靠性与稳定性有着显著的时效特性. 很多隧道塌方事故 并不是在当前掌子面发生的，而是在隧道开挖支护完成一段时间后才发生，但目前对于此类事故的研究，即 隧道围岩及支护结构的时效可靠性的研究很少. 将支护体系的时效破坏概率定义为支护体的实际位移值超过极 限位移的概率. 根据相关规范以及法国学者Louis提出的最大容许位移约为埋深的1‰的理论，可以计算得到隧 道断面上不同位置处不同方向的极限位移，即位移阀值. 利用ABAQUS有限元软件对张石高速岳家沟隧道工程 RK75+880断面进行建模分析，选择时效硬化蠕变本构模型，作出断面上各个观测点处的支护体位移时程曲线.确 定各个观测点处的极限位移，进而计算各个观测点的时效破坏概率，分析隧道断面的时效可靠性与稳定性.
Duetothecreepcharacteristicsofatunnel,thereliabilityandstabilityofthetunnelstructurehavesignifi? cantagingcharacteristics.Manytunnelcollapseaccidentsdonotoccurinthecurrentface,butafterthetunnelexcava? tionsupportiscompletedforsometime.However,thereislittleresearchontheagingreliabilityoftunnelsurrounding rockandsupportingstructure,andtheprobabilityofagingfailureofthesupportsystemisdefinedastheactualdisplace? mentvalueofthesupportbodyexceedingthelimitdisplacement.AccordingtotherelevantnormsandFrenchscholarM. Louis, themaximumallowabledisplacementisabout1‰oftheburieddepth,thelimitdisplacement,ie,thedisplace? mentthreshold,canbecalculatedindifferentdirectionsatdifferentpositionsonthetunnelsection.UsingABAQUSfi? niteelement,themodelisestablishedontheRK75+880sectionoftheZhangjihigh-speedYuejiagoutunnelproject, andtheagingcreepcreepconstitutivemodelisselectedtomakethedisplacementcurveofthesupportbodyateachob? servationpointinthesectiontomakeclearthelimitofeachobservationpoint,andthencalculatetheagingfailureproba? bilityofeachobservationpoint,andanalyzetheagingreliabilityandstabilityofthetunnelsection.