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26. Stabilising rock surfaces with a glass reinforced polymer skin

Creator:
Nemcik, Jan, Baafi, Ernest, and Porter, Ian
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, skály, rocks, bolts and anchors, TSL support, laboratory testing, 7, and 551
Language:
English
Description:
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
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

27. Structure and permeability of deep-seated rocks in the kola superdeep borehole section (SG-3)

Creator:
Gorbatsevich, Felix F., Ikorsky, Serafim V., and Zharikov, Andrey V.
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, propustnost materiálů, skály, helium, permeability, rocks, crystalline crust, anisotropy, structure, 7, and 551
Language:
English
Description:
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
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

29. The consequences of rock burst hazard for Silesian companies in Poland

Creator:
Patyńska, Renata
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, skály, rocks, rock burst hazard, parameters of rock bursts, consequences of rock bursts, 7, and 551
Language:
English
Description:
Seismic and rock burst hazards still currently appear to be important in most hard coal mines in Poland. Recently, there has been a significant increase in seismic activity in the Silesian rock mass, in comparison to previous years. In the period 2001-2010, hard coal mines experienced 33 rock bursts. The causes of rock burst occurrences are here presented, based on an analysis of the rock bursts that occurred in Polish hard coal mines. The scale of the rock burst hazard has been characterized with respect to the mining and geological conditions of the existing exploitation. The most essential of the factors influencing the status of rock burst hazard is considered to be the depth of the interval, ranging from 550 m to 1150 m. The basic factors that cause rock burst to occur are as follows: seismogenic strata, edges and remnants, goafs, faults, pillars and excessive panelling. The consequences of rock bursts are damaged and/or destroyed roadways. On this basis, the areas (ranges) of safe zones were selected as being those safe from rock burst hazard in roadways, according to the assessment conducted to establish different degrees of the risk., Renata Patyńska., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

30. The study of the relationship between cracks and seismic parameters of rocks

Creator:
Stan-Kleczek, Iwona, Sutkowska, Katarzyna, Stan, Dominika, and Zolich, Mikołaj
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, trhliny (fyzika), skály, cracks (physics), rocks, seismic measurement, crack tensor, velocity tensor, 7, and 551
Language:
English
Description:
This paper presents the relation between main crack systems and physical properties of carbonate rocks. The existence of cracks in a rock mass causes the reduction of seismic wave velocity, which is smaller in direction perpendicular to a crack plane than in direction parallel to it. This affects the occurrence of the anisotropy of seismic wave velocity, which is characteristic for rocks with preferred orientation of cracks. The existence of relationship between crack and seismic anisotropy allowed to use geophysical methods for determination of fracture density and orientation of crack systems. The research area is located in the south-east part of the Upper Silesian Trough. Tectonic observation and geophysical measurements was carried on the carbonate sequence on the both fold limbs building the Chrzanow-Wilkoszyn Syncline, originated during the Early Cimmerian movements, in the Upper Triassic - Middle Jurassic period. It was measured seismic waves velocity in the surface layers of rock mass and the strike azimuth and dip angle of cracks.The seismic anisotropy of the rock mass was done along radial profiles having common central point using P.A.S.I. Seis mograph (Mod.16S24-N). Results of field measurements were interpreted to estimate components of crack and velocity tensors. Obtained outcomes allowed to compare the existing main crack systems on the both fold limbs with seismic measurements. Eventually we have shown that seismic measurements are useful tool to study the cracks anisotropy in rocks inaccessible for direct observations., Iwona Stan-Kleczek, Katarzyna Sutkowska, Dominika Stan and Mikołaj Zolich., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public