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    Wyświetlanie 1-8 z 8
    Tytuł:
    Temperature changes in the vicinity of thermally loaded structure embedded in the soil: effect of sand content and saturation degree
    Autorzy:
    Różański, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/178365.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    transient heat flow
    temperature
    quartz
    organic matter
    degree of saturation
    Opis:
    Due to the rapid development of geothermal technologies, the problem of efficient and proper evaluation of soil thermal conductivity becomes extremely important. Factors mostly affecting the soil conductivity are the conductivity of solid phase and the degree of saturation. The former one is mainly affected by the mineral composition, in particular, by the content of quartz whose conductivity is the highest one among all the minerals forming soil skeleton. Organic matter, because of its relatively low conductivity, influences the solid conductivity as well. The problem addressed in the paper is the influence of mentioned factors on temperature changes in the vicinity of thermally loaded structure embedded in the soil medium. Numerical simulations are carried out for different values of soil thermal conductivity resulting from various quartz contents and degrees of saturation. In addition, a weak coupled – heat and water transport – problem is considered.
    Źródło:
    Studia Geotechnica et Mechanica; 2017, 39, 2; 61-71
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the interpretation of the needle probe test results: thermal conductivity measurement of clayey soils
    Autorzy:
    Różański, A.
    Sobótka, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/178202.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    grunty ilaste
    badania laboratoryjne gruntów
    przewodność cieplna
    gleba gliniasta
    laboratory studies of soils
    thermal conductivity
    clayey soils
    Opis:
    Recently, there is an increasing need for accurate and rapid thermal measurement of soils. Within a variety of available methods a needle probe test is most widely used. The needle probe method was standardized for the measurement of thermal conductivity of soils and soft rocks. In the paper, two different interpretation methods of the needle probe test were used for determination of thermal conductivity of selected soils. The first method (ASTM D5334-05 Standard approach) takes into account only the data which are recorded during heating while the second approach is based on fitting the known analytical solution to the data obtained within both heating and cooling phases. The soil samples used were classified as clayey ones. Laboratory tests were performed using the KD2Pro thermal conductivity meter (Decagon Devices) with a TR-1 sensor. The main goal of the paper is to show that the selection of interpretation method is very important and may lead to significant differences in resulting thermal conductivities.
    Źródło:
    Studia Geotechnica et Mechanica; 2013, 35, 1; 195-208
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Recovery of microstructure properties: random variability of soil solid thermal conductivity
    Autorzy:
    Stefaniuk, D.
    Różański, A.
    Łydżba, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/178952.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    simulated annealing
    heat transfer
    homogenization
    saturated soil
    Opis:
    In this work, the complex microstructure of the soil solid, at the microscale, is modeled by prescribing the spatial variability of thermal conductivity coefficient to distinct soil separates. We postulate that the variation of thermal conductivity coefficient of each soil separate can be characterized by some probability density functions: fCl(λ), fSi(λ), fSa(λ), for clay, silt and sand separates, respectively. The main goal of the work is to recover/identify these functions with the use of back analysis based on both computational micromechanics and simulated annealing approaches. In other words, the following inverse problem is solved: given the measured overall thermal conductivities of composite soil find the probability density function f(λ) for each soil separate. For that purpose, measured thermal conductivities of 32 soils (of various fabric compositions) at saturation are used. Recovered functions f(λ) are then applied to the computational micromechanics approach; predicted conductivities are in a good agreement with laboratory results.
    Źródło:
    Studia Geotechnica et Mechanica; 2016, 38, 1; 99-107
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical study of the size of representative volume element for linear elasticity problem
    Autorzy:
    Różański, A.
    Łydżba, D.
    Jabłoński, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/178756.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    kompozyt losowy
    mikrostruktura
    microstructures
    composite random
    Opis:
    In the paper, a numerical study of the size of representative volume element for the linear elasticity problem is performed. The calculations are carried out for three different types of random microstructures: checkerboard, the Ising model microstructure and Debye microstructure. It is postulated and then verified that there exists a relation between the morphology of microstructure contained in the lineal-path function and the minimum RVE size. It is confirmed, on the basis of numerical examples, that for all the microstructures considered the largest lineal-path can be treated as the size of RVE.
    Źródło:
    Studia Geotechnica et Mechanica; 2013, 35, 2; 67-81
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shape optimization of underground excavation by simulated annealing
    Autorzy:
    Sobótka, M.
    Łydżba, D
    Różański, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/178877.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    mechanika górotworu
    wyrobisko
    wyrobisko podziemne
    optymalizacja
    rock mechanics
    excavation
    underground excavation
    optimization
    Opis:
    The paper deals with the problem of shape optimization of underground tunnel excavation. In the pioneering work of Sałustowicz, the elliptic shape was assumed a priori to be an optimal one and then a determination of suitable semi-axes ratio was only the question. Two cases were distinguished there: self-supporting excavation and excavation with the structural support. An evolutionary structural optimization (ESO) procedure, employed in 2005 to optimize shape of underground excavation, confirms the assumptions concerning the case of self-supporting excavations. The case of supported excavation is considered in the present work. Optimization procedure of the simulated annealing (SA) is incorporated in the study. An energetic optimality condition, formulated in the authors’ previous papers is also adopted. Itasca FLAC software is utilized in numerical examples. Four different in situ stress ratios are investigated. The numerical results obtained confirm that the optimal shape tends to be an ellipse. The semi-axes ratio demonstrates compliance with the assumptions already existing in literature.
    Źródło:
    Studia Geotechnica et Mechanica; 2013, 35, 1; 209-218
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Efficiency of the needle probe test for evaluation of thermal conductivity of composite materials: two-scale analysis
    Autorzy:
    Łydżba, D.
    Różanski, A.
    Rajczakowska, M.
    Stefaniuk, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/178868.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    thermal conductivity
    composite
    periodic microstructure
    homogenization
    przewodność cieplna
    kompozyt
    mikrostruktura periodyczna
    Opis:
    The needle probe test, as a thermal conductivity measurement method, has become very popular in recent years. In the present study, the efficiency of this methodology, for the case of composite materials, is investigated based on the numerical simulations. The material under study is a two-phase composite with periodic microstructure of “matrix-inclusion” type. Two-scale analysis, incorporating micromechanics approach, is performed. First, the effective thermal conductivity of the composite considered is found by the solution of the appropriate boundary value problem stated for the single unit cell. Next, numerical simulations of the needle probe test are carried out. In this case, two different locations of the measuring sensor are considered. It is shown that the “equivalent” conductivity, derived from the probe test, is strongly affected by the location of the sensor. Moreover, comparing the results obtained for different scales, one can notice that the “equivalent” conductivity cannot be interpreted as the effective one for the composites considered. Hence, a crude approximation of the effective property is proposed based on the volume fractions of constituents and the equivalent conductivities derived from different sensor locations.
    Źródło:
    Studia Geotechnica et Mechanica; 2014, 36, 1; 55-62
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of bedding and backfill soil type on deformation of buried sewage pipeline
    Autorzy:
    Grosel, S.
    Pachnicz, M.
    Różański, A.
    Sobótka, M.
    Stefaniuk, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/178571.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    numerical analysis
    buried PE pipe
    Opis:
    In the paper, the influence of different types of bedding and backfill soil surrounding underground sewage duct on its deformation was analysed. Impact of increased soil lateral pressure was examined by considering the construction of an embankment nearby the underground pipeline. Numerical computations of three different variants of bedding and backfill soil surrounding the pipe were carried out. Displacements and deformation of the pipe were calculated using the finite element method with adoption of elastic-perfectly plastic constitutive model of soil. Subsequent stages of the construction were taken into account. Shear strength reduction method was applied to evaluate the factor of safety of the entire system. Finally, the results and conclusions were depicted.
    Źródło:
    Studia Geotechnica et Mechanica; 2018, 40, 4; 313-320
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A comprehensive approach to the optimization of design solutions for dry anti-flood reservoir dams
    Autorzy:
    Łydżba, Dariusz
    Różański, Adrian
    Sobótka, Maciej
    Pachnicz, Michał
    Grosel, Szczepan
    Rainer, Jakub
    Powiązania:
    https://bibliotekanauki.pl/articles/1845146.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    finite element method
    stability
    settlement
    filtration
    kriging
    Opis:
    The article proposes the methodology of designing dams of dry flood control reservoirs. The algorithm is developed so as to meet all the requirements given in the Eurocode 7 and, at the same time, to be efficient in terms of necessary calculation time. Furthermore, the presented numerical procedure enables the optimization of design solutions, e.g. the depth and length of the anti-filtration barrier, by means of parametric analyses. The approach assumes the use of numerical methods, in particular, finite element (FE) analysis. Three-dimensional (3D) reconstruction of the terrain topography and subsoil layer arrangement performed in step (1) sets the base for further analyses. In step (2), the filtration phenomena are assessed based on the 3D analysis of a transient groundwater flow. In step (3), the state of displacement is evaluated and the stability is verified for all the relevant phases of construction and operation of the facility, in particular, in the course of simulated flood detention. The analyses in step (3) are carried out on 2D models corresponding to the design cross-sections of the dam. This significantly reduces the computation time (compared to 3D analysis) and, at the same time, provides a safe estimate of factor of safety. The performance of the proposed algorithm is shown on the numerical examples of the computations concerning the dam of Szalejów Górny dry anti-flood reservoir located in Poland.
    Źródło:
    Studia Geotechnica et Mechanica; 2021, 43, 3; 270-284
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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