Murat Emre Kartal

Non-linear earthquake response of CFR DAM–reservoir–foundation systems

The aim of this article is to clearly show linear and non-linear earthquake behaviour of a concrete-faced rockfill (CFR) dam. For this purpose, a typical CFR dam model is considered with its reservoir water. Reservoir water is modelled by using fluid finite elements based on the Lagrangian approach. Free-field surface motions recorded during earthquakes are deconvolved to the base of the foundation from the soil layers for earthquake analysis. Geometrically and materially non-linear behaviours of the dam are considered in the finite element analysis. The Drucker–Prager model is used for concrete slab, and the multi-linear kinematic hardening model is used for rockfill and foundation rock in the materially non-linear analysis. Non-linear behaviour of the rockfill is obtained by the uniaxial stress–strain relation. Stress–strain curve of the rockfill is obtained using the shear modulus–shear strain relation produced for the gravels. Various joints in the CFR dam are modelled considering welded and friction contacts. In this study, one-dimensional surface-to-surface contact–target element pair based on the Coulombs friction law provides friction. According to this study, maximum displacements appear when the friction is considered in the joints. In addition, hydrodynamic pressure increases the horizontal displacements of the dam. The horizontal displacements also increase by the effect of the non-linear behaviour of the rockfill and concrete slab.

Non-linear response of the rockfill in a concrete-faced rockfill dam under seismic excitation

This study investigates the non-linear response of the rockfill in a concrete-faced rockfill dam under seismic excitation for various concrete slab thicknesses from 30 to 100 cm thick. The effect of the friction in the concrete slab rockfill interface on the non-linear response of the rockfill is also considered in the numerical solutions. The friction contact in the concrete slab joints is provided with contact elements based on the Coulomb’s friction law. The hydrodynamic pressure of the reservoir water is considered by the fluid finite elements based on the Lagrangian approach. Geometrical and material non-linear behaviours of the dam-foundation-reservoir interaction system are considered together in the finite element analyses. The Drucker–Prager model is used to obtain materially non-linear behaviour of the concrete slab. The multi linear kinematic hardening model is used for rockfill and foundation rock in the material non-linear analyses. Therefore, the uniaxial stress–strain relations of the rockfill and foundation rock are determined from the shear stress–shear strain relations of the gravel and rock, respectively. The principle compressive and tensile stresses of the rockfill are investigated along the horizontal section of the rockfill. According to numerical analyses, the most critical stresses occur in the upstream and downstream faces of the dam for the concrete slab thickness of 30 cm, while the optimum thickness for seismic performance is 58 cm.