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Determination of rock mass failure using acoustic and optical television - metamorphic rocks, Rožná Mine
Staš, Lubomír ; Waclawik, Petr ; Souček, Kamil ; Vavro, Martin ; Kukutsch, Radovan ; Rutar, Tomáš ; Nohejl, Zdeněk
In order to evaluate the geological structures on the core boreholes walls, using optical and acoustic logging methods (OBI and ABI) the boreholes were logged at the Rožná Mine. Oriented recording of the walls was performed using optical television (OPTV - Optical TeleViewer) in the horizontal borehole (VRT-H). The optical recording was supplemented by the acoustic television record (HiRAT - High Resolution Acoustic Televiewer) in the down borehole (VRT-U). The measured oriented records by OBI and ABI methods were processed and evaluated in WellCAD software for logging data processing. Based on the evaluated structural data, a structural cross-section was constructed, which was the background material for correlation with geophysical data.
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Determination of physical-mechanical properties of rock for the purpose of rock mass stress calculation based on CCBO probes measurements
Staš, Lubomír ; Waclawik, Petr ; Souček, Kamil ; Vavro, Martin
To measure the primary stress of the rock mass, the overcoring method was used using a compact conical probe CCBO. A total of four stress measurements were performed in a metamorphic rock mass formed by biotite gneiss, in a horizontal borehole marked VRT-H. For the purposes of calculating the size of the main rock mass stress components, it is necessary to know the basic physico-mechanical properties of the rock mass at the measurement site. For this reason, test specimens were prepared from the drill core, which were subsequently tested on the ZWICK 1494 mechanical press. The research report describes the samples, methodological procedures and results of physico-mechanical properties.
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Assessment of primary rock mass stress by overcoring method using CCBO probes, Mine Rožná
Staš, Lubomír ; Waclawik, Petr ; Souček, Kamil ; Vavro, Martin ; Kukutsch, Radovan ; Nohejl, Zdeněk ; Rutar, Tomáš
The measurement of the stress state of the rock mass was performed on the 20th level of the liquidated uranium mine Rožná. This site was selected as one of the possible test sites of the planned geotechnical and geophysical methods. As part of the measurements, a series of four measurements of the 3D stress tensor were carried out within the sub-horizontal (approx. + 5 °) borehole with a diameter of 76 mm. To measure the primary stress of the rock mass, the overcoring method was used using a compact conical probe, developed at the Institute of Geonics AS CR, v.v.i. in collaboration with the Japanese University of Kumamoto under the original name Compact Conical ended Borehole Overcoring method (CCBO). The research report summarizes the results of the performed measurements.
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Geological and geotechnical characterisation of the mining environment - URF Bukov II - Interim report I
Bukovská, Z. ; Rukavičková, L. ; Chabr, T. ; Morávek, R. ; Levý, O. ; Sosna, K. ; Souček, Kamil ; Vavro, Martin ; Zelinková, T. ; Dobeš, P. ; Švagera, O. ; Kryl, J. ; Soejono, I. ; Řihošek, J. ; Hanák, J. ; Čermák, F. ; Kašpar, R. ; Mareček, L. ; Nedvěd, J. ; Vavro, Leona ; Myška, O. ; Janeček, Ivan
This report describes the work carried out in the first year of the public contract Geological and geotechnical characterisation of the rock environment – PVP Bukov II. The characterisation and descriptive works are directly related to the excavation of the premises for the future underground laboratory. These include in particular: geological and geotechnical documentation of the faces and walls of the workings, petrographic, mineralogical and structural geological documentation, hydrogeological characterisation of the environment, as well as determination of the physical and mechanical properties of the rock mass in situ and in the laboratory, geophysical characterisation and monitoring of the seismic effects of blasting. An important part of this report is the research of the classification systems used to describe the rock mass and hydrogeological research. The report includes also brief overview of the work planned for the second year of the project.
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Stress state rock mass monitoring ahead of longwall No. II/501/C, Mine Staszic-Wujek, PGG, Poland -Project RFCS DD-MET
Waclawik, Petr ; Kukutsch, Radovan ; Staš, Lubomír ; Souček, Kamil ; Vavro, Leona ; Vavro, Martin ; Kubina, Lukáš ; Schuchová, Kristýna
For designing precisely the reinforcement of mine gate and reinforcing underground structures in general, knowing stress and deformation states in the rock massive in the immediate vicinity of these mine works as precisely as possible is absolutely decisive. In order to verify the rock mass stress state and its changes induced by longwall mining, the monitoring of rock mass stress changing in connection with the mine out of the coal seam No. 501, longwall face No. II/501/C in the Mine Staszic-Wujek, Poland, was suggested. The aim of the contractual research was the realisation and interpretation of the rock stress state monitoring using the CCBO (Compact Conical ended Borehole Overcoring method) and CCBM (Compact Conical ended Borehole Monitoring method) probes in the forefield of mentioned longwall face within geotechnical station. To verify stress monitoring, the survey of the state of the longwall gate was carried out using a pulse 3D scanner. The purpose was to capture deformation changes ahead of the advancing longwall face, specifically, at five stages in the ± 20 m section on each side from the installed geotechnical station.
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Tomographic investigation of the sandstone fracture toughness
Vavřík, Daniel ; Beneš, Pavel ; Fíla, Tomáš ; Koudelka_ml., Petr ; Kumpová, Ivana ; Vavro, Martin
It is well known that the measured values of the fracture toughness of quasi brittle materials are influenced by material heterogeneity, dimensions, boundary conditions, and unequal tension and compression properties. Standard testing methods supposing isotropic material, in contrary the quasi-brittle materials differ from this theoretical expectation, therefore this approach may fail. The authors present Local Fracture Toughness Testing (LFTT) method to overcome this obstacle. LFFT based on a complex methodology using a series of tomographic reconstructions recorded during specimen loading is calculated independently of the outside boundary conditions.
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Structural mapping of exploration geotechnical boreholes walls within 1st phase – Ore Zone
Waclawik, Petr ; Vavro, Martin ; Schuchová, Kristýna ; Kukutsch, Radovan ; Staš, Lubomír ; Souček, Kamil ; Georgiou, Lucie
Structural-geological analysis, i.e. fracturing assessment of the walls of geotechnical boreholes (CIS12, CIS14, CIS31 and CIS37) within the Ore Zone lithium exploratory area was carried out on the basis of optical (OPTV) and acoustic televiewer (HiRAT) records evaluation. HiRAT and OPTV probes are part of the Robertson Geologging logging equipment. The apparatus has an electric winch with a four-core logging cable, which transmits the data recorded by the probes via a data logger to a computer. The spatial data obtained from interpretation of the geotechnical boreholes records were structurally analysed. The submitted research report comprehensively summarises the findings obtained from the structural mapping of geotechnical boreholes. On the basis measured data the rock mass quality evaluation of boreholes walls were additionally done. The complex data have been allowed very precise analysis of rock mass structural conditions, which are necessary for construction geomechanical model.
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Experimental study of alkali-silica reactivity of volcanic rocks
Seidlová, Zuzana ; Přikryl, Richard (advisor) ; Vavro, Martin (referee)
(AJ) Even today, alkali-silica reaction is a significant problem in concrete-making industry. It was first described in 1940 by Stanton and since then the study of alkali-silica reaction of aggregates has proceeded notably. Despite these findings, not everything has been resolved and not all the causes and consequences of this reaction are known. To detect the alkali-silica reaction in the aggregates many methods are used, such as petrographic methods, chemical methods, and expansion tests, which examine the expansion of concrete due to the reactivity of aggregates. Petrographic methods evaluate qualitative and quantitative characteristics of aggregates but can not guarantee whether they still do not cause the reaction. Chemical tests and expansion tests provide so- called potential response (non-reactive, reactive and potentially reactive aggregates), but even they have their errors and can not be taken as a 100% indicator of the presence of alkali-silica reaction of aggregates. The thesis describes the general characteristics of alkali-silica reaction of aggregates, the mechanisms and the factors influencing its formation. It describes the fraction of the concrete in which some volcanic rocks have been used, and which are in some works identified as potentially reactive by the alkali-silica...
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Modification of rock fabric of clastic sedimentary rocks due to the Schmidt hammer test
Snížek, Petr ; Přikryl, Richard (advisor) ; Vavro, Martin (referee)
iv Summary Schmidt hammer is the instrument which is used for the assessment of rock mechanical properties and this instrument is classified as the indirect method. This method is based on the assessment of rebound value (R) of the Schmidt hammer, which is measurred by the amount of rebound of the impact plunger from the surface of tested rock. Schmidt hammer is called as the non-destructive method of rock assessment and it is called as in situ testing method as well. The main objective of this work is provement, that Schmidt hammer testing is destructive method and define degree of damage which is caused in the rock mass. Sedimentary rocks were used for the testing, mostly sandstones and arkose sandstones with different types of cement. This made it possible to test the fraction of the rock mass and the relation between fraction and type of cement. The clasts of the rocks had different properties than it was possible to find the relation between grain size and fraction of the rock. Already in procedure of the testing by Schmidt hammer it was obvious, that this metod is definitely destructive. Rock surface after hitting by plunger of Schmidt hammer gains macroscopically observeable destruction. On the surface is the circular track of the plunger and the surface is grinded. It is possible to wipe the small...
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