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Effect of loading characteristics and specimen size in split Hopkinson pressure bar test on high-rate behavior of phyllite

Mishra Sunita, Khetwal Anuradha, Chakraborty Tanusree, Basu Dipanjan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e212, 2022

EN

Split Hopkinson pressure bar (SHPB) tests are performed on Himalayan phyllite rock with five different specimen sizes and with different gas gun pressures and striker bar lengths of the SHPB device. The high-strain-rate phyllite parameters investigated are the peak stress, strain at peak stress, dynamic increase factor (DIF), strain energy absorbed, and dynamic modulus. It is observed that the dimensions of the phyllite specimens and the SHPB loading characteristics (i.e., the gas gun pressure and striker bar length) have a strong impact on the phyllite response. Given that SHPB specimen dimensions are small compared to any field rock mechanics problem, the rate-dependent rock mass properties are also determined for each rock using Hoek–Brown criteria. Numerical simluations of the SHPB tests are performed using finite element (FE) analysis in conjunction with the strain rate-dependent Johnson–Holmquist (JH-2) constitutive model to calibrate the JH-2 model parameters for phyllite. The calibrated JH-2 model parameters are dependent on the phyllite specimen size and on the magnitudes of the gas gun pressure and striker bar length. The different calibrated parameters corresponding to different specimen sizes and different SHPB loading characteristics are used to perform FE analysis of a tunnel constructed in phyllite rock and subjected to a blast load. The FE results show that the tunnel responses can significantly differ with strain rate-dependent JH-2 model parameters with difference in the mean stress and vertical displacement at the crown of the tunnel in the phyllite rock as high as 126% and 250%, respectively.

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Ancylite-(Ce) from quartz-calcite-chlorite veins in phyllite of the Opava Mountains (SW Poland)

Janeczek Janusz, Szopa Krzysztof, Fabiańska Monika

Geological Quarterly

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2020

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Vol. 64, No. 3

801--806

EN

Ancylite-(Ce) occurs in quartz-calcite-chlorite veins crosscutting the foliation of phyllite in the Dewon Quarry in the foothills of the Opava Mountains of the eastern Sudetes, south-west Poland. Irregularly shaped grains of ancylite are up to 67 μm long and 22 μm wide. The compositional range of ancylite, determined by electron microprobe, is expressed by the empirical formula: (Sr0.65-0.55Ca0.19-0.14Fe0.03-0.00)∑0.87-0.69 (Ce0.58-0.50Nd0.26-0.22La0.26-0.21Pr0.06-0.05Sm0.05-0.04Gd0.07-0.03Dy0.01-0.00)∑1.29-1.05 (CO3)2(OH1.07-0.99F0.22-0.0.06)∑1.29-1.05· 0.95-0.93H2O. Ancylite crystallized directly from CO2-rich hydrothermal solutions as the last mineral in the veins following precipitation of calcite. The solution temperature, estimated using various chlorite geothermometres, was in the range of 260-340°C.

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Mineralogy and organic geochemistry of phyllite from the Dewon-Pokrzywna deposit, the Opava Mountains (SW Poland)

Sawicka N., Janeczek J., Fabiańska M., Bahranowski K., Krzykawski T., Matuszewska A.

Geological Quarterly

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2018

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Vol. 62, No. 4

817--828

EN

Phyllites from the Dewon-Pokrzywna deposit in the Opava Mts., SW Poland, were investigated by XRD (Rietveld method), XRF, EPMA, SEM, and ATR-FTIR from the perspective of their potential usage as a buffer and/or backfill material in a geological repository of radioactive waste. Organic matter dispersed in the phyllite matrix was analysed by GC-MS. Fine-grained Mg-Fe-muscovite (13 to 29 wt.%), Fe-ripidolite (10 to 25 wt.%), detrital quartz (20 to 46 wt.%), and albite (7 to 28 wt.%) ± microcline, illite or illite/smectite, and kaolinite are major minerals in phyllite samples. The chlorite/muscovite ratio ranges from 0.65 to 1.1. Mg-annite inherited from the precursor rock is a minor constituent. Detrital ilmenite is a dominant accessory mineral. Ancylite-(Ce) occurs in quartz-calcite-ripidolite veins. Two types of phyllite have been distinguished based on the proportion of phyllosilicates to silt fraction: argillaceous (47 to 55 wt.% phyllosilicates) and silt-rich (28 wt.% phyllosilicates). Argillaceous phyllite shows elevated content of alumina and moderate concentration of silica. It is highly enriched in Fe compared to phyllites from other localities worldwide. The BET specific surface area of argillaceous phyllite ranges from 1.73 to 3.64 m2/g. Whole-rock chemical composition, mineral assemblages, chlorite geothermometry, and the occurrence of aliphatic hydrocarbons suggest that argillaceous phyllite originated from a pelagic pelite protolith under low-temperature (260-370°C) greenschist to subgreenschist facies conditions. Persistent biomarkers are indicative of bacterial degradation of planktonic organic matter suspended in a high water column. Enrichment in Fe-rich chlorite and Mg,Fe-muscovite, low volume of interconnected pores with dominant mesopores suggest that argillaceous phyllite from the Dewon-Pokrzywna deposit is a potential candidate for a buffer and/or backfill material.

4

Wstępna charakterystyka strukturalno-petrograficzna fyllitów z Podmąchocic w regionie łysogórskim Gór Świętokrzyskich

Salwa S.

Przegląd Geologiczny

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2006

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Vol. 54, nr 6

513-520

EN

Four tectonic deformation events are recorded in the Middle Cambrian rocks from Kamecznica Podmąchocicka. The D1 event took place in Cambrian and originated from tremor. Its structural record includes synsedimentary folds and seismites. The D2–D3, and most probably also D4, events resulted from progressive deformation produced by tectonic compression initially from NE and then NNE direction. Folding was accompanied by green facies metamorphism, which resulted in development of phyllites. Composition and characteristic deformations of minerals suggest that they were produced in temperature ranging from 300ş to 400şC and differential pressure above 1.7 kbar (170 MPa). The combined deformation and metamorphism resulted in three generations of foliation — S1 to S3 defined by crenulated cleavage planes. New blasts of quartz, small scale muscovite (sericite), chlorites and sporadically biotite grew within these cleavage planes. Deformations and metamorphism took place after the Middle Cambrian, but before the Late Silurian. It is indicated by presence of the quartzitic sandstone pebbles in the Miedziana Góra Conglomerates.