ABSTRACT
The history of sprayed concrete strength and stiffness at early and young ages plays a key role in the safe and successful construction of sprayed concrete lining (SCL) tunnels. Before maturity, SCL linings are highly deformable when loaded, which facilitates arching effects and plasticisation of the surrounding ground, while the rapid hardening of the sprayed concrete can prevent excessive ground deformation and subsequent failure. The ability to model the time-dependent behaviour of sprayed concrete is thus critical to achieve optimised designs. PLAXIS Concrete model is an isotropic elastoplastic constitutive model that captures the time-dependent mechanisms of aging, creep, and shrinkage. In this paper, the structural performance of elephant feet in soft ground caverns simulated with and without the Concrete model is compared. The benefits of using nonlinear time-dependent concrete constitutive models in the design of such features are evidenced. The suitability of the Eurocode 7 design framework is also discussed.
