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    Tytuł:
    Analysis of Youngs modulus for Carboniferous sedimentary rocks and its relationship with uniaxial compressive strength using different methods of modulus determination
    Autorzy:
    Małkowski, P.
    Ostrowski, Ł.
    Brodny, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/92023.pdf
    Data publikacji:
    2018
    Wydawca:
    Główny Instytut Górnictwa
    Tematy:
    Young's modulus
    rock properties
    rock deformability
    elasticity limits
    carboniferous sedimentary rocks
    modulus ratio MR
    moduł Younga
    właściwości skał
    odkształcalność skał
    granice elastyczności
    karbońska skała osadowa
    współczynnik MR
    Opis:
    Young’s modulus (E) is one of the basic geomechanical parameters used in rock engineering in practice. It is determined based on uniaxial compressive test (UCS). However, according to International Society of Rock Mechanics it can be calculated by three different ways: as the tangent, secant and average modulus. The results from each method are significantly different. The UCS tests was carried out on 237 rock specimens with the slenderness ratio 2 of Carboniferous claystones, mudstones and sandstones. The axial deformation was always measured automatically by the displacement measurement device (LVDT) built into the testing machine and connected to the hydraulic piston. Then the Young’s modulus was calculated for each test by all three methods. The analysis of the results is presented in this paper to show the difference between all the three moduli calculated for each specimen, and to recommend the best method of Young’s modulus determination. First, the typical range of the elastic linear deformability for the chosen rock types was determined as 25-75% of the peak strength at confidence interval 95% for these sedimentary rocks. The modulus value distributions obtained from each calculation method were compared using statistical parameters: mean value, median, minimum, maximum, standard deviation, mean difference at confidence interval 95%, and non-uniformity coefficient. The proportions between average-secant modulus (Eav/Esec) and average-tangent modulus (Eav/Etan) for the rock samples were estimated. For the studied rocks the obtained values were: 1.10-1.32% for Eav/Esec, 1.08-1.25% for Etan/Esec and 1.01-1.06 for Eav/Etan (for Etan with the range of 20-80% of peak strength). These values show low coherence between secant and average modulus (ca. 23% difference) and good consistency of average and tangent modulus. Based on the analysis, tangent Young’s modulus is recommended as the guiding one at the constant range of 30-70% of the ultimate stress. Secant Young’s modulus, as it comprises not only elastic strain but the pore compaction as well, should be named as modulus of deformability. This conclusion was further confirmed by the regression analysis between UCS and E. The highest regression coefficients and the lowest standard error of the regression was obtained for tangent Young’s modulus determination method. In addition, modulus ratio MR for claystones, mudstones and sandstones was studied and determined as 274, 232 and 223 respectively.
    Źródło:
    Journal of Sustainable Mining; 2018, 17, 3; 145-157
    2300-1364
    2300-3960
    Pojawia się w:
    Journal of Sustainable Mining
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Tournaisian 40Ar/39Ar age for alkaline basalts from the Lublin Basin (SE Poland)
    Autorzy:
    Pańczyk, M.
    Nawrocki, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059639.pdf
    Data publikacji:
    2015
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    alkaline basaltic rocks
    Ar-Ar geochronology
    Carboniferous
    Lublin Basin
    Opis:
    The main aim of this study is to define precisely the age of the alkaline basalts occurring within the lowermost part of Carboniferous succession in the northeastern part of LublinBasin(drill core Parczew IG-7 and IG-9; SE Poland). The new, whole-rocks 40Ar/39Ar data constrain the age of volcanic activity and emplacement of alkaline basalts to the Late Tournaisian (348 ± 0.8 Ma) with possible prolongation to the Middle Visean (338.5 ± 0.7 Ma). The younger age is however of evidently poorer quality than the older one. The new data caused to correlate the volcanic processes occurring within the Lublin Basin with alkaline intrusions drilled inNE Poland inside the Paleozoic cover of the East European Platform. They also correspond to the volcanoclastic levels defined in different parts of the Trans European Suture Zone in Poland.
    Źródło:
    Geological Quarterly; 2015, 59, 3; 473--478
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stephanian-Early Permian basaltic trachyandesites from the Sławków and Nieporaz-Brodła Grabens near Kraków, Southern Poland
    Autorzy:
    Lewandowska, A.
    Rospondek, M. J.
    Nawrocki, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/191897.pdf
    Data publikacji:
    2010
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    Upper Carboniferous/Permian volcanism
    a-a lava flows
    autoclastic breccias
    basaltic trachyande-sites
    transitional calc-alkaline to alkaline rocks
    hydrous magma
    Opis:
    In the Kraków-Lubliniec section of the major Hamburg-Kraków-Dobrogea Fault Zone (HKDFZ), the Stephanian-Early Permian magmatic activity was simultaneous with subsidence/uplift of formed blocks. In the proximity of the uplifted areas the sedimentation started with fanglomerates, distally passing into playa siltstone and was accompanied by volcanism. In the Nieporaz-Brodła graben, basaltic trachyandesite a-a lava flows with autoclastic breccias reach ca. 150 m in thickness. The weathering recorded as adhesive rims around breccia clasts reflects palaeosoil formation during quiescence periods between the eruptions. The eruptions were effusive although scoriaceous lava indicates high volatile content of the magma. The water content before eruption had to be over 2 wt. percent. Only then the crystallisation model predicts accurately the type, composition and order of the crystallising phases. Thus, the basaltic trachyandesite magma originated from a source containing hydrous phase (i.e., amphibole or phlogopite). All the studied basaltic trachyandesites had fayalitic olivine on their liquidus reflecting the crystallisation stage in a magma chamber at crustal depths. During final decompression on the magma ascent due to water exsolution, the olivine was followed by plagioclase, spinel, augite, ilmenite, apatite, K-feldspar and residual high-K rhyolitic glass. The high potassium content of these volcanics was thus a primary feature reflecting the source geochemistry and differentiation trend, and its consequence was potassium metaso- matism. Due to water exsolution the glass was altered, however, homogenous interstitial glass survived in some rocks. The glass is strongly enriched in incompatible trace elements, showing that it is a highly fractionated residual melt fraction of the basaltic trachyandesite magma. Thus, the glass geochemistry reflects the trend of fractional crystallisation indicating that co-occurring K-rich felsic rocks were not derived from the same magma. All the basaltic trachyandesites studied have calc-alkaline to alkaline affinity. They contain fayalitic olivine and are low in MgO <5 wt. %, Cr and Ni, the features characteristic for evolved magmas. They show significant negative Sr/Sr*> 0.5-0.80 and small Eu/Eu* > 0.9-1.0 anomalies suggesting fractionation of plagioclase. The Eu/Eu* anomaly is probably compensated by amphibole retaining in the source. Negative Nb, Ti anomalies suggest Fe-Ti oxide fractionation characteristic for calc-alkaline evolution trend. A significant enrichment in LREE relatively to HREE (La/Yb > 10) indicates subduction-related metasomatism. However, the described tectonic context is inconsistent with subduction related characteristics. Concluding, the observed geochemical characteristics indicate remarkable role of water in magma evolution. The volcanism was related to strike-slip dextral movement along the Kraków-Lubliniec section of HKDFZ, transformed into crustal extension and subsidence, the features typical for the formation of pull-apart basins, in the late stages of the Variscan orogen evolution.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2010, 80, No 3; 227-251
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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