The Institute of Rock Structure and Mechanics is focused on research connected with both natural rocks and rock environment on the Earth´s crust, as well as with artificially produced geomaterials, celebrates its 50th anniversary this year. and Zuzana Weishauptová.
Estimating the pre- failure points for rocks during laboratory testing is not a trivial task. In this study, a new approach is introduced that utilizes change in the slope of the load-deformation curves of rock in the loading cycle for marking the onset of failure point during uniaxial test of a given rock. At each step, load-deformation data footprints of the rock under test are inspected and a decision is made whether the failure has started or not. The load-deformation data obtained from different tests of different rocks are examined including; Norite, Granite, Limestone, Sandstone, Siltstone and Marble. The computational results over 154 cored rock samples show that the proposed approach locates the onset of failure point for a given rock with an acceptable degree of accuracy., Deniz Mamurekli., and Obsahuje bibliografii
The stressed state of the rock mass in the area of the Outokumpu deep drill hole, Finland, was investigated by the boundaryelement method in three mutually orthogonal planes with regard for the massif geological structure. It was found that subhorizontal components of the stress field are determined by tectonic forces acting on the boundaries of the European part of the Eurasian lithospheric plate. In the drill hole vertical section the widest variations of this field gradient occur at the depths of an ophiolite sequence in the range of 1.8-2.0 km., Stepan Savchenko and Feliks Gorbatsevich., and Obsahuje bibliografii
Habitat use and selection of 14 Alpine ibex males were studied in the Gran Paradiso National Park. Alpine meadows were always overused and positively selected, because this habitat constituted an important food resource for the ibex. Even if rocks (30%) and stone ravines (22%) were the most frequented habitats in the study area, their use was lower than their availability because they offered few trophic resources. Pastures were used only in spring when the ibexes were looking for those sites just free from snow and with fresh vegetation. Stone ravines, where the ibexes rested in the hottest days, were most used in summer. Rocks were most used in winter: rock-faces are the only sites where the risk of avalanches is low and where it is still possible to find snow-free patches. Larch woods were especially used in winter and spring when it was still possible to find snow-free patches. The home range sizes proved to be influenced by the amount of Alpine meadows and rocks.
Magnetickou anizotropii hornin objevil pravděpodobně Ising [1], když si povšiml, že magnetická susceptibilita jemně vrstevnatých hornin čtvrtohorního stáří, varvitů, je výrazně větší, když se měří podél vrstevnatosti, že když se měří kolmo na vrstevnatost. Na jeho práci navázal Graham [2], který upozornil, že magnetická anizotropie může být využita ve strukturní analýze hornin, a Granar [3], který prezentoval ucelenou metodiku měření a matematického zpracování měření. Od počátku šedesátých let, kdy byly vyvinuty dostatečně citlivé a přesné přístroje umožňující měřit magnetickou anizotropii takřka všech typů hornin, se datuje značný rozmach této metody., František Hrouda., and Obsahuje seznam literatury
Using rocks composing the Pechenga complex geologic and petrographic peculiarities, metamorphism and physical properties of rocks from prehnite-pumpellyite to amphibolite facies have been studied. The study showed that the rock densities increase from prehnite-pumpellyite to amphibolite facies (earth's surface). Rocks of epidote-amphibolite and amphibolite facies (earth's surface) showed the lowest velocities of compression waves. The values of velocity as well as density under depth conditions tend to increase from prehnite-pumpellyite to amphibolite facies. A new quantitative method – acoustopolariscopy was used to distinguish rocks of different facies of metamorphism.The data obtained (density, velocity characteristics, elastic moduli and Poisson's ratios) reflect the actual properties of the massif rocks and can be used for geophysical investigations and technical calculations in mining.
Mine roadways developed in highly stressed strata are subject to roof shear, which under severe conditions may manifest as the well known symptom of guttering, particularly at the roadway edge leading into the major horizontal stress. This roof shear can progressively reduce the effectiveness of bolt confinement of the strata within the lower roof horizon affecting stability of the immediate roof. This paper presents the results of a study to investigate the effectiveness of polymers as skin reinforcement in highly stressed coal mine roadways, as they may provide better roadway skin support than the currently used steel mesh. A large concrete block intercepted with artificial joints and reinforced with steel bolts without skin support, was loaded until significant slip occurred along the joints. Upon loading, a roof cavity resembling a gutter developed, as some of the jointed concrete parted from the free surface. In addition to bolts, subsequent models with identical fracture planes were supported with steel mesh or with glass reinforced polymer skin bonded to the free side. Loads and displacements were compared for models with and without skin reinforcement. As expected the skin support helped resist gutter formation, to various degrees, while increasing the residual strength of the concrete block. It was found that there was significantly less bedding displacements in models with the polymer skin, when compared with both steel mesh and no skin reinforcement. This suggests that there would be benefits to using a spray on polymeric skin as surface support in roofs subject to severe roof shear., Jan Nemcik, Ernest Baafi and Ian Porter., and Obsahuje bibliografii
Preferential flow paths in the crust, as caused by the presence of the Luchlompolo fault in the drilled section of the Kola Superdeep Borehole (SG-3) and the dip angle of the rock structural elements (layering, schistosity, banding), are favourable for migration of deep fluids to the Earth’s surface. An investigation of the structure, anisotropy and permeability of rocks under PT-conditions in the SG-3 section, in addition to the occurrence of He-isotopes, reveals that the high-permeability zones of the exposed crustal segment are related to two important structural elements of the section: in the upper zone - to the Luchlompolo fault, in the lower one to the contact between the Proterozoic and Archaean complexes. The obtained results on the rock samples from SG-3 indicate a rough correlation between permeability and elastic anisotropy of various rock samples. Simulating increased PT-conditions, corresponding to the relevant depths of 6-8 km document the overlapping temperature and pressure effect, i.e. resulting in a sharp decrease of rock permeability., Felix F. Gorbatsevich, Serafim V. Ikorsky and Andrey V. Zharikov., and Obsahuje bibliografii
Elastická anizotropie hornin je důležitý geofyzikální parametr, který využíváme ke klasifikaci hornin při petrofyzikálních studiích, pro interpretaci seismických a karotážních měření a pro studium kůry a svrchního pláště Země., Tomáš Lokajíček, Zdeněk Pros, Karel Klíma., and Obsahuje seznam literatury
Using the FLAC3D numerical simulation method, the characteristics of mining stress evolution, fault activation patterns, and fault energy evolution characteristics are simulated and analyzed in the process of the footwall and hanging wall working face heading to a normal fault. The study shows that the fault cut off the mining stress propagation of overlying strata, and the stress blocking effect due to the fault is evident. When working faces head towards a fault, the abutment pressure and the vertical stress of the surrounding rock increase first and subsequently decrease. The abutment pressure of the coal wall and fault is highest when the distances to the fault are 40 m and 30 m for the footwall and hanging wall working faces, respectively. Moreover, the hanging wall mining stress is higher than the footwall mining stress. Fault activation in high-located strata precedes that in low-located strata when working faces head towards the normal fault. Energy is gradually accumulated before unstable fault events take place because of mining, and fault instability quickly releases a lot of energy. The mining stress concentration and fault activation due to faults easily result in rock bursts and mine seismicity, Wu Quan-sen, Jiang Li-shuai and Wu Quan-lin., and Obsahuje bibliografické odkazy