Volumetric studies of mica spatial distribution inside samples of Westerly and Czech granites (Mrakotin, Liberec, and Brno syenite) were performed using a neutron tomography method. A significant difference in the neutron attenuation coefficients of mica and other rock-forming minerals of the granites studied yielded a large neutron radiography contrast and, as a result, allowed us to perform a detailed analysis of three-dimension structural data based on the neutron tomography reconstruction procedure. The morphology and spatial distribution of the mica phase within studied granites were obtained. Tomography data were compared to results provided by other experimental methods commonly used in rock mechanics research such as optical and electron microscopy, as well as ultrasonic shear-wave measurements. The benefits and limitations for application of the neutron tomography method for studies of granite like rocks are discussed.
In order to quantitatively study the influence of temperature and confining pressure on brittle plasticity of granite, this paper reviews previous studies regarding quantitative calculation methods for the brittle-plastic behaviors of rocks and their mechanical characteristics under high temperatures and confining pressures. Combining the experimental results for temperatures and confining pressures with theoretical calculations of brittleness and plasticity allowed quantitative calculations and evaluations for the brittleness and plasticity of granite to be obtained. The main conclusions are as follows. (1) High temperatures lead to a transformation of granite from brittle failure to plastic failure. Comparing six conventional empirical equations from the literature, the B3 and B6 can more accurately describe the relationship between the brittleness and temperature of granite. (2) When the confining pressure σ3 is less than 20 MPa, the internal pore structure and fractures of granite are re-compacted and reduced, which gradually increases its brittleness. With the increasing confining pressure, the pore structure changes again after exceeding 20 MPa. This initiates new cracks, which ultimately leads to a decrease of the granite brittleness. (3) The abrupt temperature for the brittle-plastic transformation of granite is approximately 800 °C, and the brittle-plastic transformation of granite is mainly affected by temperature and not the confining pressure.
The water retention capacity of coarse rock fragments is usually considered negligible. But the presence of rock fragments in a soil can play an important role in both water holding capacity and in hydraulic conductivity as well. This paper presents results of maximum water holding capacity measured in coarse rock fragments in the soil classified as cobbly sandy loam sampled at High Tatra mountains. It is shown, that those coarse rock (granite) fragments have the maximum retention capacity up to 0.16 volumetric water content. Retention curves of the four particular granite fragments have shown water capacity available for plants expressed in units of volumetric water content of 0.005 to 0.072 in the soil water potential range (0, -0.3 MPa). Available water capacity of stone fragments can contribute to the available water capacity of soil fine earth considerably and help to plants to survive during dry spells. and Hodnoty vodnej retenčnej kapacity hrubozrnných častíc skeletu v pôdach sa zvyčajne považujú za zanedbateľné. Avšak prítomnosť častíc skeletu v pôdach môže významne ovplyvňovať hodnoty vodnej kapacity pôdy ako aj jej hydraulickej vodivosti. Tento príspevok prezentuje výsledky merania maximálnej vodnej kapacity skeletu obsiahnutého v pôde. Pôdne vzorky boli odoberané v lokalite FIRE, Vysoké Tatry. Podľa meraní, hodnoty maximálnej retenčnej kapacity skeletu dosahovali 0,16 objemovej vlhkosti. Na základe retenčných kriviek pre 4 vybrané žulové kamene môžeme povedať, že hodnoty využiteľnej vodnej kapacity, vyjadrené v jednotkách objemu vody v pôde sa pohybovali od 0,005 do 0,072 pre vodný potenciál pôdy od 0 do -0,3 MPa. Využiteľná vodná kapacita častíc skeletu takto môže významne doplňovať využiteľnú vodnú kapacitu jemnozeme a pomáha rastlinám prežiť suché obdobia.