The problem of bumps occurrence in deep mines during the long wall mining appears to be one of the most serious one in the design of engineering of mining. The bumps are caused for various reasons, but basically it is an aftermath of the accumulated energy, which is released under some unfavorable conditions. In this paper the influence of given dislocations and their slope in a coal seam are studied based. The numerical tool is the free hexagon method. This method belongs to a set of discrete element methods and enables us to define and calculate stresses in a natural way along the interfacial boundaries of adjacent particles (elements). Since the bumps are affected by a possible slip along the dislocations, dynamical response has to be taken into account. The velocity of excavation of the mine is considered by successive change of values of Eshelby’s forces on the face of the wall., Petr Pavel Procházka, Jiřina Trčková and Tat Seng Lok., and Obsahuje bibliografii
The sustainable ecology belongs to the most important issues today. In this field a use of recycled materials is of great interest to people. Consequently, incorporation of industrial waste, concrete and brick scraps and other rubbish into products for civil engineering use is very important. Certain results from experiments carried out in laboratory on standard samples are emerged in this paper. Since the material is not yet enough approved, three main targets are addressed. The first involves the behaviour of fiber reinforced concrete based on aggregates from various recycled material. Then the influence of distance among two or more fibers is observed. For completeness the results from shear tests are presented in the end of this paper., Jiřina Trčková and Petr Procházka., and Obsahuje bibliografii
Physical mass properties of various types of rocks were ascertained, and their relationships are discu ssed in this article. Basedon water permeability and mercury intrusion porosimetry methods, conductivity coefficient, porosity, and pore size distribution were determined. Furthermore, bulk and particle densities of rocks we re determined. All laboratory tests were carried out according to Czech versi on of the Technical specif ication CEN ISO/TS 17892-11:2004. The above-mentioned specification has the status of the Czech standard (ČSN, CEN). Permeability and porosity are in close relation, and it could be assumed that its relationship is linear, i.e., with increasing porosity, permeability increases as well. This relationship is influenced by other rock properties, such as the amount of open and closed pores with in the rock sample, size, and distribution of pores or mineral admixtures. From this point of view, it is necessary to study these physical properties of rocks as well, because this enables an overall analysis of rocks and its possible use for engineering constructions, Jan Šperl and Jiřina Trčková., and Obsahuje bibliografické odkazy
The techniques of the method of the coupled modelling was substantially extended and used for solving problems connected with underground constructions for various materials and appropriate structural systems. In principle, a combination of linear effects of the external loading and material and time-dependent nonlinear change in structures was considered. Assessment of rock behaviour in surrounding of utility tunnels, solution of the structural strength below foundation, back analysis of reinforced soil slopes and studies of slopes endangered by groundwater were carried out., Petr Procházka and Jiřina Trčková., and Obsahuje bibliografii
To obtain the starting point for theoretical numerical computations the fibre reinforced concrete construction properties, adhesion of cement mixture with steel and polypropylene fibres and changes in its tension properties commensurate with number and weight percentage in the tested specimen were tested under laboratory conditions., Jiřina Trčková and Karel Řezba., and Obsahuje bibliografické odkazy
Modal composition and grain-size characteri stics, physical and mechanical propertie s of three samples of Archean gneisses of the Kola series from the depths of 6.8 to 8.4 km of the Kola Superdeep Borehole (KSDB-3) and two collections of their surface analogues were analysed. On the basis of a comparison of the petrographic characteristics of the borehole samples and analogues, it was found that not all analogues are equivalents of corresponding core samples completely. Mechanical properties of core samples are affected by depth of the core sample position in the borehole. This work forms part of the research in the frame of the INTAS Project No.314 "Geodynamics in the cross-section of the Kola superdeep"., Jiřina Trčková, Vladimír Šrein, Martin Šťastný and Roman Živor., and Obsahuje bibliografické odkazy