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1

Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table

Sawicki A., Kulczykowski M., Jankowski R.

Archives of Hydro-Engineering and Environmental Mechanics

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2012

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Vol. 59, nr 3-4

101-112

EN

Theoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important to determine the stress field as function of the base acceleration. It is particularly important for a proper interpretation of shaking table tests, where the base acceleration is controlled but the stresses are hard to measure, and they can only be deduced. Preliminary experiments have shown that small accelerations do not lead to essential settlements, whilst large accelerations cause some phenomena typical for limit states, including a visible appearance of slip lines. All these problems should be well understood for rational planning of experiments. The analysis of these problems is presented in this paper. First, some heuristic considerations about the dynamics of experimental system are presented. Then, the analysis of boundary conditions, expressed as resultants of respective stresses is shown. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. Such an approach leads to determination of the limit base accelerations, which do not cause the plastic state in soil. It was shown that larger accelerations lead to increase of the lateral stresses, and the respective method, which may replace complex plasticity analyses, is proposed. It is shown that it is the lateral stress coefficient K0 that controls the statically admissible stress field during the shaking table experiments.

2

Strains in Sand Due to Cyclic Loading in Triaxial Conditions

Sawicki A., Mierczyński J., Świdziński W.

Archives of Hydro-Engineering and Environmental Mechanics

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2009

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Vol. 56, nr 1-2

85-98

EN

The experimental results dealing with the cyclic loading of sand samples in triaxial conditions are presented. These results show the development of both the volumetric and deviatoric permanent strains due to a large number of loading cycles. The analysis of experimental data has led to the formulation of semi-empirical constitutive equations, expressed in the incremental form, for these strains as functions of the cyclic shear stress amplitude, number of loading cycles and the initial stress state, around which the cyclic shearing takes place.

3

Pore-Pressure Generation and Liquefaction of Granular Soil Tested in Triaxial Conditions

Mierczyński J., Sawicki A.

Archives of Hydro-Engineering and Environmental Mechanics

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2009

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Vol. 56, nr 3-4

139-147

EN

The paper deals with modelling of pore-pressure generation in saturated sand subjected to triaxial cyclic loading in undrained conditions. The model proposed links the pore-pressure generation with the cyclic loading induced compaction of the same sand, but tested in fully drained conditions. The governing equation for the pore-pressure changes is derived from the assumption that no volumetric strain develops in saturated sand in undrained conditions. The numerical solutions are compared with experimental data, for a large number of loading cycles.

4

Numeryczne modelowanie roboczych cykli konstrukcji w warunkach korozyjnych

Dudda W.

Diagnostyka

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2004

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Vol. 32

31--36

PL

Opracowanie dotyczy analitycznych i numerycznych narzędzi deterministycznej oceny zachowania się konstrukcji pracujących w ekstremalnych warunkach, znajdujących się pod wpływem wieloparametrowych i/lub cyklicznych obciążeń mechanicznych, termicznych i chemicznych. Poszczególne elementy konstrukcji ulegają plastycznej i korozyjnej degradacji oraz dysypują energię, na którą składają się wkłady od nieodwracalnych zjawisk typu praca na odkształceniach niesprężystych. Trwałość konstrukcji i jej elementów oceniana jest za pomocą kryterium energetycznego. W pracy główny nacisk został położony na zamodelowanie i numeryczne zaimplementowanie zjawisk degradacyjnych, takich jak cykliczna plastyczność, wywołana obciążeniami mechanicznymi i termicznymi, korozja naprężeniowa, korozja elektrochemiczna i korozja niskocykliczna.

EN

Supplement of analytical and numerical tools of deterministic evaluation of working structure behavior in extreme conditions, which are under multiparameter and/or cyclic mechanical, thermal and chemical loads, is the aim of the dissertation. Particular structure units go under plastic and corrosion degradation and they dissipate energy, which consists of irreversible effect contributions, like a work on the inelastic strains. The structure and its units' lifetime is estimated according to energy criterion. Dissertation emphasizes the modeling and numerical implementation of degradation effects, such as cyclic plasticity, generated by mechanical and thermal loads, stress corrosion, electrochemical corrosion and low-cyclic corrosion.

5

A Simple model of sinking of breakwater due to earthquake-induced subsoil liquefaction

Sawicki A.

Archives of Hydro-Engineering and Environmental Mechanics

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2003

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Vol. 50, nr 4

381-400

EN

The paper deals with engineering analysis of breakwater behaviour due to earthquake- induced subsoil liquefaction. First, a simple model enabling analysis of pore-pressure generation in saturated granular soils, due to cyclic loading, is outlined. It is also shown how this model can be applied to the analysis of seabed behaviour during earthquakes. Then, a simple model of breakwater resting on saturated subsoil in which the phenomena of pore-pressure generation and liquefaction take place is described. This model enables estimation of changes of seabed effective reaction due to pore-pressure generation, as well as subsequent sinking of the breakwater due to subsoil liquefaction. Numerical examples illustrate theoretical considerations and show links between breakwater behaviour and earthquake characteristics.