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BEHAVIOUR OF FRICTIONAL JOINTS IN STEEL ARCH YIELDING SUPPORTS ZACHOWANIE POŁĄCZEŃ CIERNYCH W PODATNYCH ŁUKOWYCH OBUDOWACH STALOWYCHThe loading capacity and ability of steel arch supports to accept deformations from the surrounding rock mass is influenced significantly by the function of the connections and in particular, the tightening of the bolts. This contribution deals with computer modelling of the yielding bolt connections for different torques to determine the load-bearing capacity of the connections. Another parameter that affects the loading capacity significantly is the value of the friction coefficient of the contacts between the elements of the joints. The authors investigated both the behaviour and conditions of the individual parts for three values of tightening moment and the relation between the value of screw tightening and load-bearing capacity of the connections for different friction coefficients. ANSYS software and the finite element method were used for the computer modelling. The solution is nonlinear because of the bi-linear material properties of steel and the large deformations. The geometry of the computer model was created from designs of all four parts of the structure. The calculation also defines the weakest part of the joint's structure based on stress analysis. The load was divided into two loading steps: the pre-tensioning of connecting bolts and the deformation loading corresponding to 50-mm slip of one support. The full Newton-Raphson method was chosen for the solution. The calculations were carried out on a computer at the Supercomputing Centre VSB-Technical University of Ostrava.

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The total load-bearing capacity of steel arch yielding roadways supports is among their most important characteristics. These values can be obtained in two ways: experimental measurements in a specialized laboratory or computer modelling by FEM. Experimental measurements are significantly more expensive and more time-consuming. However, for proper tuning, a computer model is very valuable and can provide the necessary verification by experiment. In the cooperating workplaces of GIG Katowice, VSB-Technical University of Ostrava and the Institute of Geonics ASCR this verification was successful. The present article discusses the conditions and results of this verification for static problems. The output is a tuned computer model, which may be used for other calculations to obtain the load-bearing capacity of other types of steel arch supports. Changes in other parameters such as the material properties of steel, size torques, friction coefficient values etc. can be determined relatively quickly by changing the properties of the investigated steel arch supports.

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Rockbursts in the course of coal winning in the Upper Silesian Coal Basin have presented a considerable problem. Rockbursts with focuses in more distant surroundings of the affected mine workings are prevailing. The maximum effects of rockbursts occur above all in gateroads and this impact is connected with the lower load bearing capacity of the roadway supports. Research into the behaviour of steel arch roadway support under dynamic loads based on mathematical modelling is being carried out. Steel support sets are being modelled by means of shell elements in programming software ANSYS, and the dynamic load from the roadway side has either been characterised by an initial speed or by an impulse of force. The outputs of modelling were as follows: shape and nature of permanent strain in the support, critical quantity of energy causing permanent strain in the support, degree of total plastic strain (deformation) as well as the influence of interaction of adjacent rock on the above mentioned characteristics.

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REINFORCING MEASURES OF STEEL ROADWAY SUPPORT IN ROCKBURST PRONE AREAS WZMACNIANIE STALOWYCH OBUDÓW CHODNIKOWYCH W OBSZARACH ZAGROŻONYCH TĄPNIĘCIAMIDue to the strong impacts of rockbursts in Ostrava-Karvina coalfield, which affect especially roadways and cross-cuts of longwall panels, it is necessary to strengthen standard steel roadways and breakthroughs supports. However it is a little different task in comparison with main solved problems of mining safety (Kidybinski, 2011), the use of reinforcing complementary bolts seems to be very effective. A varieties of numbers and locations of such rockbolts have been analyzed and compared from the viewpoint of the stability under dynamic events on the base of 3D mathematic modeling. The method used for computer modeling has been FEM applied by ANSYS code. It deals with the shape and nature the following issues: the deformation of a steel support, strain and deformation of reinforcing bolts, the critical energy by which a permanent strain is caused and the influential interaction of the adjacent rock on the above mentioned characteristics. A recommendation for number and location of reinforcing complementary bolts is also contained.Keywords: roadway support, rockburst, bolting Z uwagi na silne skutki tąpnięć występujących w obszarze zagłębia węglowego Ostrava-Karlina, których skutki najsilniej odczuwane są w rejonie chodników i przecinek konieczne jest wzmocnienie stalowych obudów tunelowych i obudów w przejściach. Jest to jednak drobny problem w porównaniu z głównymi problemami zapewnienia bezpieczeństwa kopalni (Kidybiński, 2011), jako że zastosowanie kotwienia do dodatkowego wzmocnienia obudowy wydaje się zabiegiem skutecznym. Przeanalizowano lokalizację i ilość zastosowanych kotwi. Wyniki porównano z wynikami badań stabilności w warunkach dynamicznych, przeprowadzonych z wykorzystaniem trójwymiarowego modelowania matematycznego. Modelowanie przeprowadzono w oparciu o metodę elementów skończonych, z wykorzystaniem programu ANSYS. W oparciu o metodę określa się kształt i charakter odkształceń obudów stalowych, naprężenia i odkształcenia wzmocnień kotwi, graniczną wartość energii przy której następuje trwałe odkształcenie oraz wzajemne oddziaływania z otaczającymi skałami i ich wpływ na wyżej wymienione charakterystyki. Podano także rekomendacje odnośnie ilości i lokalizacji uzupełniających kotwi.Słowa kluczowe: obudowa wyrobisk, tąpnięcia, kotwienie