ISSMGE International Journal of Geoengineering Case Histories · 2010 · 55 citations · 5 references
EngineeringCivil EngineeringGeological EngineeringGeotechnical EngineeringTunnel EngineeringTunneling EngineeringTunnel DesignTunnel Excavation MethodsTunnel GeologyTunnel Structural AnalysisTunnelingUnderground Excavation MethodsComposite ReinforcementConvergence MonitoringFull-face ExcavationShotcreteShotcrete LiningTunnel Deformation AnalysisTunnel Excavation ResponseTunnels
Large‑scale tunnel excavation in poor‑quality rock that exhibits squeezing behaviour is the focus of this study. The authors model time‑dependent squeezing using validated constitutive laws, applying a two‑stage excavation with composite pre‑reinforcement and deformable elements in shotcrete, and analyze the Saint Martin La Porte adit with semi‑analytical and numerical methods. Model predictions are compared with convergence monitoring data.
This paper deals with full face excavation of large size tunnels in rock masses of very poor quality which exhibit squeezing behaviour. Time dependence is accounted for explicitly by using constitutive models which have been validated with reference to laboratory testing and in situ performance monitoring. The case study of the Saint Martin La Porte access adit (Lyon-Turin Base Tunnel) is taken as illustration. In this adit an innovative excavation-construction method is being used to cope with the severely squeezing Carboniferous zone encountered. An essential feature of this method is a two-stage excavation sequence with installation of a composite pre-reinforcement/reinforcement system with deformable elements embedded in the shotcrete lining. The tunnel response has been analysed by both semi-analytical and numerical solutions with close attention paid to the constitutive models adopted. Results of modelling are compared with convergence monitoring data.
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