Wyniki wyszukiwania - BazTech

1

Seismic analysis of Fractured Koyna Concrete Gravity Dam

Ouzandja Djamel, Messaad Mokhtar, Berrabah Amina T., Belharizi Mohamed

Archives of Hydro-Engineering and Environmental Mechanics

|

2023

|

Vol. 70, nr 1

29--47

EN

Seismic analysis of a fractured dam is a generally complex problem. This paper presents an earthquake behavior investigation of a fractured concrete gravity dam considering dam-reservoir-foundation rock interaction. The Koyna dam profile, located in India, is adopted in this study. The nonlinear finite element analyses are conducted taking into account empty and full reservoir cases, to exhibit the hydrodynamic effect of reservoir water on the dam earthquake response. The hydrodynamic pressure is modeled by fluid finite elements based on a Lagrangian approach. Transient analyses take into account material and connection nonlinearity. Drucker-Prager model is employed in nonlinear analyses for the dam concrete and foundation rock. The structural crack between the top and bottom blocks of the dam is presented by surface-to-surface contact elements based on Coulomb’s friction law in order to simulate the behavior of contact joints and deformation of blocks. The distribution of horizontal displacements and principal stresses along the dam height is investigated for empty and full reservoir cases.The failure processes of two potential failure modes of cracked dam, i.e, the separation and sliding of top block during an earthquake, are examined.

2

3D Lagrangian modelling of saltating particles diffusion in turbulent water flow

Bialik R., Nikora V., Rowiński P.

Acta Geophysica

|

2012

|

Vol. 60, no. 6

1639-1660

EN

A 3D Lagrangian model of the saltation of solid spherical particles on the bed of an open channel flow, accounting for turbulence-induced mechanisms, is proposed and employed as the key tool of the study. The differences between conventional 2D models and a proposed 3D saltation model are discussed and the advantages of the 3D model are highlighted. Particularly, the 3D model includes a special procedure allowing generation of 3D flow velocity fields. This procedure is based on the assumption that the spectra of streamwise, vertical and transverse velocity components are known at any distance from the bed. The 3D model was used to identify and quantify effects of turbulence on particle entrainment and saltation. The analysis of particle trajectories focused on their diffusive nature, clarifying: (i) the effect of particle mobility parameter; (ii) the effect of bed topography; and (iii) the effect of turbulence. Specifically, the results of numerical simulations describing the abovementioned effects on the change in time of the variance are presented. In addition, the change in time of the skewness and kurtosis, which are likely to reflect the turbulence influence on the spread of particles, are also shown. Two different diffusion regimes (local and intermediate) for each of the investigated flow conditions are confidently identified.

3

Two-dimensional modelling of wave motion in shallow-water areas

Kapiński J.

Archives of Hydro-Engineering and Environmental Mechanics

|

2004

|

Vol. 51, nr 1

3-24

EN

A new mathematical model for prediction of a two-dimensional wave motion in shallow water is presented herein. It can be applied to investigate shoaling, diffraction, refraction, breaking, bottom friction and wave run-up on a beach, as well as mass transport and orbital motion. The model also includes an oblique wave approach to the shore and irregular bottom topography. Such engineering constructions as seawalls, breakwaters and groins are simulated numerically. Simple results of computations, shown in graphic form, indicate possible practical applications of the model.

4

Description of dispersed two-phase turbulent flow in the Lagrangian approach

Pozorski J., Minier J.-P.

Turbulence : international journal

|

1998

|

Vol. 4

7-32

EN

Turbulent two-phase participate flows are considered. Emphasis is put on the modelling issue and, in particular, on the class of models based on the Langevin equation. New model for particle dispersion in the Lagrangian approach is introduced. Physical arguments behind this model are quite different from those previously proposed in the literature, for some averaged characteristics of the relative motion of solid-fluid particle pairs are considered rather than instantaneous relative velocities. The model takes both particle inertia and external force effects into account. Its performance is examined by comparison with existing experimental data on particle dispersion in grid turbulence and with the outcome of a numerical experiment (the Large-Eddy Simulation). The obtained results are found to be satisfactory.