|
|
Effects of Water Jets on CNTs/concrete composite
Foldyna, Vladimír ; Foldyna, Josef
Results of the resistance of carbon nanotubes concrete composite (CNTs/concrete\ncomposite) to the action of pulsating and continuous water jets are presented in\nthis paper. This work brings advanced results of fully hydrated CNTs/concrete\ncomposite (after 28 days) and it follows up the research of this composite\nhydrated 7 days. The experiments were focused at the determination of erosion\neffects of both types of water jets impinging the surface of reference (concrete) and\nCNTs/concrete composite samples. Erosion effects of water jets were evaluated in\nterms of material removal rate. Tests were performed at various operating\nparameters of continuous and pulsating water jets.
|
|
|
Application of high speed water jet technology for concrete repair
Bodnárová, L. ; Sitek, Libor ; Foldyna, Josef ; Jarolím, T.
This article brings selected knowledge from the long-term cooperation between\nthe Brno University of Technology, the Faculty of Civil Engineering, the Institute of\nTechnology of Building Materials and Components, and the Academy of Sciences of\nthe Czech Republic, v.v.i., Institute of Geonics, Ostrava – Poruba in the field of\nthe interaction of high-speed water jets and concrete, especially with regard to\nthe use of high-speed water jet technology for the removal of surface layers of\nconcrete during repair of concrete.
|
|
| |
|
|
Parametric study of usability of selected surveying equipment for monitoring of mine workings stability in undermined areas
Kajzar, Vlastimil ; Kukutsch, Radovan ; Koníček, Petr ; Waclawik, Petr ; Šňupárek, Richard
Although the deformation measurements are in mining practice routine activities, the development of information and surveying technology shows, that it is possible to approach this problematics in a new way. One of the options is the application of terrestrial 3D laser scanning technology, which can be successfully used both for purposes of monitoring - deformations of objects on undermined area and mine workings at all.\nSubmited parametric study presents the use of laser technology in the research activities of the Institute of Geonics, v.v.i., within the ICT-PU project. This study deals with technical and theoretical aspects of laser scanning, which verification in situ has been a precondition for the subsequent successful application of this technology both on the surface and in the mining environment. The main scope of the study is dedicated to the deployment of selected technology in solving specific tasks. In the undermined areas were achieved knowledge used in solving the problems of monitoring the stability of slopes and rock faces of mining chasm. In the underground mine workings, this technology has been successfully deployed for the purposes of the spatial deformation monitoring of selected longwall corridor at mine Karvina and also for the long-term monitoring of coal pillars in Room and Pillar pilot project at ČSM coal mine.\nAt the end of a parametric study is special space devoted to the limiting factors of 3D laser scanning and also to the summary of best practices of scanning in such highly exposed conditions.\n
Fulltext: content.csg -  PDF
Plný tet: UGN_0472640 - PDF
|
|
|
Monitoring of surface changes caused by underground mining in the Karviná region
Doležalová, Hana ; Kajzar, Vlastimil
Geodetic monitoring of the Louky locality revealed irregularities in the development of the subsidence depression and it also helped to document the changing terrain due to ongoing reclamation activities. Repeated GNSS measurements recorded not only the size of subsidence of individual points, but also the size and direction of horizontal displacement of these points, which revealed the influence of undermining in the area of interest, and in its surroundings. It turned out that particularly the significant tectonic fault A forms a barrier of the influence of underground mining. The subsidence depression develops differently than the models of the predicted subsidence expected, especially in the area between the tectonic faults X and A. The method of aerial photogrammetry recorded not only the subsidence caused by underground mining, but also the extent and size of the changes caused by the ongoing reclamation of the surface.
Fulltext: content.csg - PDF
Plný tet: UGN_0464599 - PDF
|
|
|
Stress state rock mass monitoring ahead of longwall No. 371 202 at 2ndA block, Mine Plant 2, OKD, a.s
Waclawik, Petr ; Ptáček, Jiří ; Koníček, Petr ; Vavro, Martin ; Staš, Lubomír ; Souček, Kamil ; Kukutsch, Radovan ; Kajzar, Vlastimil
Generally, the accurate knowledge of the stress strain state of the rock mass in the neighbourhood of the mining galleries and underground openings is absolutely critical for their precise support designing, not only in the vicinity of them, but also at a greater distance from them if the phenomenon affecting the rock mass stress fields occurs. Measurement (investigation) of the rock stress is usually carried out by interpretation of the rock mass deformation processes, which can be relatively precisely observed and measured. The roadways are loaded not only by rock pressures in the front of the coalfaces but also by destress blasting realised in the overburden rock seam in the scope of the rockburst prevention. In addition, the rock stress distribution is influenced by old mining activities too, for example by abandoned coal pillars in the seams in overburden, respectively by goaf in the excavated seam. All of these factors can significantly affect the stress-strain behaviour of the rock mass around the mining works.
|
|
|
Stress state rock mass monitoring ahead of longwall No. 371 202 at 2ndA block, Mine Plant 2, OKD, a.s
Waclawik, Petr ; Ptáček, Jiří ; Koníček, Petr ; Vavro, Martin ; Staš, Lubomír ; Souček, Kamil ; Kukutsch, Radovan ; Kajzar, Vlastimil
Generally, the accurate knowledge of the stress strain state of the rock mass in the neighbourhood of the mining galleries and underground openings is absolutely critical for their precise support designing, not only in the vicinity of them, but also at a greater distance from them if the phenomenon affecting the rock mass stress fields occurs. Measurement (investigation) of the rock stress is usually carried out by interpretation of the rock mass deformation processes, which can be relatively precisely observed and measured. The roadways are loaded not only by rock pressures in the front of the coalfaces but also by destress blasting realised in the overburden rock seam in the scope of the rockburst prevention. In addition, the rock stress distribution is influenced by old mining activities too, for example by abandoned coal pillars in the seams in overburden, respectively by goaf in the excavated seam. All of these factors can significantly affect the stress-strain behaviour of the rock mass around the mining works.
|
|
| |
|
|
Reinterpretation of Carboniferous strata in the borehole no Stonava SV 2. The Czech part of the Upper Silesian basin
Horak, J. ; Martinec, Petr ; Waclawik, Petr ; Málek, O.
Borehole no Stonava SV 2 was realized in 1968 - 70 yrs. for the verification of the stratigraphy of Carboniferous strata in Karviná area. This borehole was very important for regional study. The original interpretation of the stratigraphy of the Ostrava and Karviná Fms in this borehole was inaccurate, that is, without the revision, used the current publications. The borehole SV 2 was situated between the Stonava and Albrechtice tectonic fault, in block in a Karviná graben. Strong tectonic disturbances in this tectonic structure lead without revision of correlation horizons incorrect determination of litostratigraphy and the thickness of individual members of Ostrava and Karviná Fms in Carboniferous strata. Because the boundaries of individual members of the Ostrava Fm are given into the ceilings of the marine horizon, it is a mistake to disregard the new findings from the study of their association of fauna in marine horizons and geological structure in a new mine boreholes, realized later in the neighbouring of the borehole SV 2. In the case of good primary geological documentation of borehole Stonava SV 2, however, it is possible at any time proceed to reinterpretation.
|
|
|
Determination of boundary of individual members in Ostrava Fm in the Czech part of the Upper Silesian basin
Horák, J. ; Martinec, Petr ; Málek, O.
In the Czech part of the Upper Silesian basin is currently uses the definition of boundary between individual members in Ostrava Fm after F. ŘEHOŘ & J. ZEMAN (1958). On the basis of the revision of the historical geological documentation of boreholes from surface (boreholes denoted as „NP“) and mining documentation from 50-ties years of a past century and new a detailed study of boundary between the individual members of the Ostrava Fm (with respect to correlation horizons in this boreholes) is presented the new proposal to the adjustment of the current boundary between the individual members in Ostrava Fm.
|
guest ::
