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1
Content available Modelling of the Response of Partially Saturated Non-cohesive Soil Subjected to Undrained Loading
Świdziński W., Mierczyński J., Smyczyński M.
Archives of Hydro-Engineering and Environmental Mechanics
|
2018
|
Vol. 65, nr 1
11--29
EN
The paper deals with the modelling of the undrained response of non-cohesive partially saturated soils subjected to triaxial compression. The model proposed is based on an incremental equation describing the pre-failure response of non-cohesive soils during shearing. The original model, developed by Sawicki, was modified by taking into account pore fluid compressibility. The governing equation makes it possible to simulate effective stress paths under undrained conditions. Numerical results are compared with experimental data.
2
Content available Response of Partially Saturated Non-cohesive Soils
Świdziński W., Mierczyński J., Mikos A.
Archives of Hydro-Engineering and Environmental Mechanics
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2017
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Vol. 64, nr 3-4
187--207
EN
This paper analyses and discusses experimental results of undrained triaxial tests. The tests were performed on non-cohesive partially saturated soil samples subjected to monotonic and cyclic loading. The tests were aimed at determining the influence of saturation degree on soil’s undrained response (shear strength, excess pore pressure generation). The saturation of samples was monitored by checking Skempton’s parameter B. Additionally, seismic P-wave velocity measurements were carried out on samples characterized by various degrees of saturation. The tests clearly showed that liquefaction may also take place in non-cohesive soils that are not fully saturated and that the liquefaction potential of such soils strongly depends on the B parameter.
3
Content available Mechanical Properties of Granular Soils: Triaxial versus Plane Strain Investigations
Sawicki A., Sławińska J., Mierczyński J., Smyczyński M.
Archives of Hydro-Engineering and Environmental Mechanics
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2016
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Vol. 63, nr 2-3
135--156
EN
The paper compares the pre-failure behavior of granular soils investigated in the classical triaxial apparatus and in the true triaxial apparatus, under plane strain conditions. Both experiments are described within the framework of an incremental model of the pre-failure behavior of sands. The methods of tensor algebra are used to compare theoretical predictions with experimental results. The analysis presented deals with the pre-failure deformations of fully drained sand, aswell as with its undrained behavior, including static liquefaction and the specific behavior of an initially dilative soil. Some key questions of soil mechanics are discussed, for instance, whether soil parameters determined from one configuration, such as triaxial conditions, can be applied in other cases.
4
Content available Theoretical analysis of model seabed behavior under water wave excitation
Sawicki A., Mierczyński J., Smyczyński M.
Studia Geotechnica et Mechanica
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2015
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Vol. 37, nr 2
33--37
EN
Theoretical analysis of the behavior of a model seabed subjected to water wave excitation is presented. The experiments were performed in the wave flume at the Danish Technological University in Lyngby. Such experiments are unique in engineering sciences and therefore provide unique empirical data for testing various models of the seabed. A controversial explanation of the experiments is presented in the literature. The goal of this research was to study pore pressure changes caused by water waves and the subsequent liquefaction of the seabed. The authors of the present contribution offer their own theoretical explanation of the wave flume experiments and discuss errors found in the literature cited. The analysis is based on the classical soil mechanics, including the Biot type approach.
5
Content available Some effects of intrinsic cyclic loading in saturated sands
Sawicki A., Mierczyński J.
Journal of Theoretical and Applied Mechanics
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2015
|
Vol. 53 nr 2
285--293
EN
This paper presents original results of triaxial experiments performed at a cyclically changed pore pressure (intrinsic cyclic loading). The results display unusual behaviour of saturated sand subjected to such atypical loading. Some features of this behaviour are shown, including the following effects: static liquefaction of initially contractive sand, apparent creep of initially dilative sand, initial anisotropy, etc. Some differences between the classical geotechnical understanding of the effects of external cyclic loadings (such as earthquakes) and those caused by intrinsic cyclic loadings (such as wave-induced pressures) are discussed.
6
Content available remote Reakcja nawodnionych osadów poflotacyjnych na obciążenia cykliczne w warunkach bez odpływu wody z porów
Świdziński W., Mierczyński J.
Inżynieria Morska i Geotechnika
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2015
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nr 3
466--473
PL
Wyniki badań prowadzonych w cyklicznym aparacie trójosiowego ściskania na próbkach osadów poflotacyjnych zawierających różne zawartości frakcji drobnej, poddanych obciążeniu w warunkach bez odpływu wody z porów. Badania na próbkach rekonstytuowanych, jak też o nienaruszonej strukturze, pobranych z masywu osadów OUOW „Żelazny Most”.
EN
The results of cyclic triaxial tests carried out on post-flotation tailings specimens with various content of fines tested in drained and undrained conditions. The tests made on both reconstitutive as well as undisturbed samples taken from the mass of tailings stored in the large depository „Żelazny Most”.
7
Content available Liquefaction Resistance of a Granular Soil Containing Some Admixtures of Fines
Sawicki A., Mierczyński J., Mikos A., Sławińska J.
Archives of Hydro-Engineering and Environmental Mechanics
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2015
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Vol. 62, nr 1-2
53--64
EN
The paper deals with the mechanics of sand with some admixtures of fines. The basic question is whether such admixtures are liquefiable or not. Experimental results show that admixtures of fines do not essentially influence the liquefaction susceptibility of granular soils. The original experimental investigations support this conclusion.
8
Content available Compaction/Liquefaction Properties of Some Model Sands
Sawicki A., Mierczyński J., Sławińska J.
Archives of Hydro-Engineering and Environmental Mechanics
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2015
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Vol. 62, nr 3-4
121--133
EN
The compaction/liquefaction characteristics of two model sands are determined experimentally. One sand (Istanbul) is used in shaking table investigations, and the other (Dundee) in geotechnical centrifuge experiments. Both types of these highly sophisticated experiments are planned to be applied to test theories of seabed liquefaction. The first step of these experiments is to determine the parameters of model soils, which is the main goal of this paper.
9
Content available Structure and calibration of constitutive equations for granular soils
Sawicki A., Sławińska J., Mierczyński J.
Studia Geotechnica et Mechanica
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2014
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Vol. 36, nr 4
35--46
EN
The form of incremental constitutive equations for granular soils is discussed for the triaxial configuration. The classical elasto-plastic approach and the semi-empirical model are discussed on the basis of constitutive relations determined directly from experimental data. First, the general structure of elasto-plastic constitutive equations is presented. Then, the structure of semiempirical constitutive equations is described, and a method of calibrating the model is presented. This calibration method is based on a single experiment, performed in the triaxial apparatus, which also involves a partial verification of the model, on an atypical stress path. The model is shown to give reasonable predictions. An important feature of the semi-empirical incremental model is the definition of loading and unloading, which is different from that assumed in elasto-plasticity. This definition distinguishes between spherical and deviatoric loading/unloading. The definition of deviatoric loading/unloading has been subject to some criticism. It was therefore discussed and clarified in this paper on the basis of the experiment presented.
10
Content available Basic set of experiments for determination of mechanical properties of sand
Sawicki A., Mierczyński J., Świdziński W.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2014
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Vol. 62, nr 1
129--137
EN
A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.
11
Content available remote Moduł ścinania gruntu sypkiego przy małych naprężeniach
Sawicki A., Świdziński W., Mierczyński J.
Czasopismo Techniczne. Środowisko
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2012
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R. 109, z. 3-Ś
91--102
PL
Przeanalizowano problem modułu ścinania piasku przy małych naprężeniach, jak te występujące w badaniach warstwy gruntu na stole sejsmicznym. Wstępne obliczenia osiadań takiej warstwy, dla wartości modułu ścinania przyjętej z badań gruntu przy znacznie wyższych naprężeniach, doprowadziły do wyniku znacznie niższego niż pomierzone osiadania. W związku z tym zapytano, jaki powinien być moduł ścinania, aby uzyskać zgodność przewidywań teoretycznych z doświadczeniem? Okazało się, że ten moduł powinien być przynajmniej o rząd wielkości mniejszy od wartości przyjętej do wstępnych obliczeń. Problemu, jakim jest model ścinania piasku przy małych naprężeniach, nie rozstrzygnęły również przedstawione w pracy, wstępne wyniki badań prędkości propagacji fali sejsmicznej w próbce gruntu, umieszczonej w aparacie trójosiowym.
EN
The problem of shear modulus of sand at small stress level corresponding to that occurring in the shaking table tests of sandy layer is analysed. Calculated settlements of such layer for shear modulus determined at significantly higher stresses appeared to be much lower than measured ones in the experiments. Estimated shear modulus based on back analysis was at least one order lower than that assumed in primary calculations. Even additional experiments determining shear modulus from the measurement of seismic wave velocity by bender elements did not solve this problem.
12
Content available remote Badania reakcji sprężystej gruntów niespoistych za pomocą pomiaru prędkości fali sejsmicznej
Świdziński W., Mierczyński J.
Czasopismo Techniczne. Środowisko
|
2010
|
R. 107, z. 1-Ś
63-82
PL
W artykule przedstawiono wyniki badań doświadczalnych związanych z pomiarem prędkości fali ścinającej przeprowadzonych na piasku "Skarpa". Badania wykonano w aparacie trójosiowego ściskania wyposażonym w elementy typu bender. Omówiono metodę wyznaczania właściwości sprężystych gruntu na podstawie pomiaru prędkości fali sejsmicznej oraz przeanalizowano różne sposoby interpretacji wyników w celu wyznaczenia rzeczywistego czasu przejścia fali przez próbkę gruntu. Wyznaczono zależności prędkości fali ścinającej oraz wartości modułów ścinania w funkcji zagęszczenia i średniego ciśnienia efektywnego.
EN
The results of measurements of shear wave velocity of "Skarpa" sand in triaxial apparatus are presented. The method of determination of elastic response of non-cohesive soils by seismic waves is described. Various test interpretation procedures and its influence on the results are discussed. The relations between shear wave velocity and shear moduli, soil density and mean effective stress are determined and anlysed.
13
Content available remote Badania laboratoryjne zjawiska podatności cyklicznej w nawodnionym gruncie niespoistym
Świdziński W., Mierczyński J.
Inżynieria Morska i Geotechnika
|
2009
|
nr 4
271-280
PL
Wyniki badań doświadczalnych na nawodnionym piasku "Skarpa", o początkowym stanie dylatywnym, poddanym cyklicznemu trójosiowemu ściskaniu, w warunkach bez drenażu. Rozwój odkształceń plastycznych w warunkach stałej objętości i generacja wysokich wartości ciśnienia wody w porach określone mianem podatności cyklicznej. Wpływ początkowego stanu gruntu i wartości amplitudy naprężenia na liczbę cykli do osiągnięcia podatności cyklicznej. Rola linii niestabilności w rozwoju zjawiska podatności cyklicznej.
EN
The results of undrained tests carried out on fully saturated, initially dilative "Skarpa" sand subjected to cyclic triaxial shearing in undrained conditions. Development of plastic strains associated with pore water pressure generation called as cyclic mobility. Influence of initial state of the soil tested as well as stress amplitudes on the number of loading cycles necessary for initiation of cyclic mobility. The role of instability line in the development of cyclic mobility.
14
Content available Strains in Sand Due to Cyclic Loading in Triaxial Conditions
Sawicki A., Mierczyński J., Świdziński W.
Archives of Hydro-Engineering and Environmental Mechanics
|
2009
|
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.
15
Content available 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
|
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.
16
Content available remote Zachowanie się gruntów niespoistych w warunkach trójosiowego rozciągania
Świdziński W., Mierczyński J.
Inżynieria Morska i Geotechnika
|
2007
|
nr 4
226-232
PL
Wyniki badań doświadczalnych przeprowadzonych na piasku Skarpa poddanym trójosiowemu rozciąganiu, przy którym naprężenia poziome są zawsze większe niż pionowe. Sposób prowadzenia eksperymentów trójosiowego rozciągania. Wyznaczenie powierzchni granicznych dla piasku luźnego oraz zagęszczonego poniżej linii hydrostatycznej naprężeń. Reakcja próbek o początkowym stanie kontraktywnym dla piasku suchego oraz nawodnionego w warunkach bez drenażu. Charakterystyki linii niestabilności w warunkach trójosiowego ściskania.
EN
The results of experiments made on Skarpa sand in triaxial extension conditions where the lateral stresses are always grater than the vertical ones. Methodology of the triaxial extension tests. Determination of ultimate surfaces for loose and dense sand below the hydrostatic axis of stresses. The response of contractive soils in drained and undrained conditions. Instability lines for triaxial compression and extension conditions.
17
Content available remote Zagęszczanie się piasków w cyklicznym aparacie trójosiowego ściskania
Świdziński W., Mierczyński J.
Zeszyty Naukowe Politechniki Białostockiej. Budownictwo
|
2006
|
Z. 28, t. 1
299-314
PL
W pracy przedstawiono wyniki badania doświadczalnego cyklicznie ścinanego piasku w aparacie trójosiowego ściskania. Opisano podstawowe cechy cyklicznego aparatu trójosiowego oraz sposób prowadzenia eksperymentów i pomiarów. Reakcję gruntu na przyłożone obciążenia cykliczne zinterpretowano w formalizmie teorii zagęszczania i upłynniania rozwijanej od lat w IBW PAN.
EN
In the paper the experimental results of cyclically sheared sand in triaxial conditions are presented. Basic features of cyclic triaxial apparatus as well as the tests and measurements carried out are described. The compaction of sands due to cyclic triaxial loading has been interpreted in the framework of compaction/liquefaction theory originally developed in the Institute of Hydro-Engineering.
18
Content available Wave-induced stresses and liquefaction in seabed according to the biot-type approach
Sawicki A., Mierczyński J.
Archives of Hydro-Engineering and Environmental Mechanics
|
2005
|
Vol. 52, nr 2
131-145
EN
The problem of wave-induced stresses and liquefaction in the seabed according to the Biot-type approach is discussed. The first part of the paper deals with critical analysis of approaches presented in recent literature. It is shown that such approaches do not lead to proper description of the process of wave-induced pore-pressure generation and subsequent liquefaction of seabeds. The second part of this paper deals with the generalisation of the Biot-type approach to the case of shear modulus depending on mean effective stress.
19
Content available Instability line as a basic characteristic of non-cohesive soils
Świdziński W., Mierczyński J.
Archives of Hydro-Engineering and Environmental Mechanics
|
2005
|
Vol. 52, nr 1
39-58
EN
In the paper, the experimental results of undrained response of non-cohesive soil subjected to either monotonic or cyclic loading, are analysed and discussed. The analysis was based on the results of comprehensive testing programme made of "Skarpa" sand investigated in the triaxial compression. Two main undrained behaviours such as liquefaction and cyclic mobility were experimentally identified and studied. In the analysis of undrained behaviour, the concept of steady state of deformation has been adopted. It was shown that the undrained response of non-cohesive soils is governed by different failure mechanisms than in the case of drained samples. In undrained failure mechanism, an important role is played by an instability line, which may be identified with the initiation of potential liquefaction.
20
Content available remote Wyznaczanie linii stanu ustalonego w piaskach
Świdziński W., Mierczyński J.
Inżynieria Morska i Geotechnika
|
2003
|
nr 3-4
194-199
PL
W pracy przedstawiono wyniki badań wykonanych w aparacie trójosiowego ściskania w celu wyznaczenia linii stanu ustalonego piasku średniego "Skarpa". Badania przeprowadzono na nawodnionych próbkach w stanie luźnym w warunkach bez odpływu wody z porów gruntowych, jak również na próbkach zagęszczonych badanych w warunkach z pełnym drenażem. Opisano procedury przygotowywania próbek oraz omówiono szczegółowo kolejne fazy badania. Przedstawione wyniki potwierdzają istnienie wspólnej krzywej, zwanej linią stanu ustalonego.
EN
The results of triaxial compression tests of determination of steady state characteristic of medium "Skarpa" sand are presented. The tests were made on saturated loose specimens in undrained conditions as well as dense drained samples. The procedures of sample preparation and detailed description of every experimental phases are presented and discussed. The results shown confirm the existence of steady state line.
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