Containment Lining Solutions and Hydrodynamic Stability of Tailings Dam

The study investigates the impact of reservoir lining on the hydrodynamic stability of a tailings dam. A 3D coupled fluid-solid finite element model was used for detailed seepage analyses based on conventional flow-net and steady seepage conditions. Pore pressure, stationary seepage velocities, static liquefaction and the ratio between manifested and critical hydraulic gradients were predicted under three different lining conditions. The highest potential for internal erosion and heave was observed in the lined reservoir and starter dam scenario. Although there are environmental benefits, the incorporation of liners in dam design requires a comprehensive engineering assessment of the negative hydrodynamic effects

3D nelinearna dinamična analiza kamnite pregrade, ki temelji na IZIIS softwaru

This paper treats the 3D nonlinear dynamic behavior of a rock-fill dam based on the Mohr-Coulomb failure criterion. The dam is situated in a steep, narrow, “V-shaped” rigid canyon. The concept of a massless rock foundation is treated, for which a certain part of the rock is included in the model. The dam-rock interface was modeled by contact elements, which allowed certain relative displacements between the two media of different stiffnesses. The generation of the 3D mathematical model was related to the topology of the terrain, and the nonlinear dynamic response was based on the "step-by-step" linear-acceleration direct-integration method, making use of the Wilson-θ method. The convergence process was in accordance with the Newton-Raphson method. First, the initial static effective stresses existing in the conditions of the established stationary filtration through the clayey core were defined. The analysis was based on an original FE program for the static and dynamic analyses of rock-fill dams, as well as a FE program for the solution of the stationary filtration process through the clayey core. The dynamic response of the 3D model of the dam was defined for the effect of harmonic excitations. Dynamic analyses in the linear and nonlinear domains were performed for the purpose of comparing the results. The time histories of the linear and nonlinear responses were defined for selected sections and nodes of the model, the tension cut-off zones, the plastic deformations, and the stress-shear strain relationships. The coefficient against the sliding of the potential sliding surfaces was also defined. It can be concluded that 3D analyses as well as a nonlinear material treatment of the soils built in the dam are imperative for a proper assessment of the stability of rock-fill dams situated in narrow canyons.V tem prispevku je opisano 3D nelinearno dinamično obnašanje kamnite pregrade. Za kamnito maso je upoštevan material, ki zadovoljuje Mohr-Coulombov kriterij porušitve. Pregrada se nahaja v strmem, ozkem, ostrem kanjonu, v obliki črke \u27V\u27. Obravnavan je koncept modela »brezmasnega kamnitega temelja«, pri čemer je določen del kamnine vključen v model. Kontaktna ploskev med kamnino in pregrado je modelirana s kontaktnimi elementi, ki omogočajo relativne premike med materialoma različne togosti. 3D matematičnega modela je bil izbran glede na topologijo terena. Nelinearni dinamični odziv temelji na direktni integracijski metodi linearnega pospeška, kis e izvaja \u27korak za korakom\u27 z uporabo metode Wilson-θ. Konvergentni postopek je v skladu z Newton-Raphsonovo metodo. Najprej so bile določene začetne statične efektivne napetosti, ki so v stacionarnih pogojih filtracije skozi glinasto jedro. Analiza temelji na originalnem programu s končnimi elementi za statično in dinamično analizo kamnitih pregrad, kakor tudi na programu s končnimi elementi za reševanje stacionarnih filtracijskih procesov skozi glinasto jedro. Dinamični rezultat 3D modela pregrade je definiran za efekt harmoničnih indukcij. Dinamične analize v linearni in nelinearni domeni so bile izvedene zaradi primerjave rezultatov. Časovni poteki linearnih in nelinearnih odzivov so bili določeni za izbrane odseke in točke modela, natezne razpoke, plastične deformacije in napetostno deformacijske odnose. Določili smo tudi koeficient varnosti potencialnih drsnih površin. Ugotavljamo, da so 3D analize, kakor tudi nelinearno obravnavanje materialov vgrajenih v pregrado, nujne za pravilno oceno stabilnosti kamnitih pregrad izvedenih v ozkih kanjonih

Eigenvalue solution for arch dams: ADAD-IZIIS Software

3D earthquake analyses of complex engineering structures such as arch dams are based on the determination of a range of eigenvalues and associated eigenvectors. Despite the variety of practical numerical eigensolutions available in the literature, the method of subspace iteration was found to offer time efficient and accurate eigenvalue solutions appropriate for large systems with high degrees of freedom. This paper presents the theoretical principles of the well known subspace iteration method implemented in the existing ADAD-IZIIS software for finite-element analyses of arch dams