Steel yielding arch support constructed of V profiles is commonly used to protect galleries and, in some cases, to reinforce or secure a shaft support. For this purpose, a closed, circular-shaped arch support is used, with arches overlapped by clamps that are typical for this type of construction. The support has high resistance to the impact of even (distributed over the entire surface of the support) load, however, as a result of significant deformation associated with a change in the radius of the curvatures, the support shows limited yielding capacity. This is due to the increase in resistance to slide on the locks, resulting from changes in the geometry of the ring caused by the rock mass. This article presents the results of research and analysis concerning the elements of the arch support with notches in arches. The research team tested the effect of the depth and location of the notches of the section’s flanges on the load impacting on the clamp’s bolts and the strength of the roof support. Moreover, the tests covered the influence of the number and location of clamps in a frictional joint on the change in the nature of work and yielding capacity. Finally, the research included both strength tests of the support’s elements, as well as strength analyses based on the finite element method.

The conduction of mining activity under the conditions of rock bursts and rock mass tremors means that designers often utilise support systems comprising various configurations of steel arch, rock bolt and surface support. Particularly difficult geological and mining conditions, when wire mesh does not provide sufficient dynamic resistance, it requires an additional reinforcement with wire rope lacing in the form of steel ropes installed between the bolt ends and fixed to them by means of various rope clamps (e.g. u-bolt clamps). Bench tests were conducted to compare the strength of wire ropes under static and dynamic loading. The tests involved wire ropes with an internal diameter of Ø15.7 mm. Tests under static loading demonstrated that the cable bolts transferred a maximum force F_{s max} = 289.0 kN without failure, while the energy absorbed until failure was E _1s = 16.6 kJ. A comparative test result analysis for the wire ropes used in the bolt designs revealed that the influence of dynamic loading forces has a significant effect on reducing the rope load capacity, which results in the brittle cracking of the wires in the rope. Although the average dynamic force leading to wire rope failure F _dmax = 279.1 kN is comparable to the minimum static force F_min = 279 kN defined in the relevant standard, the average energy E_1d absorbed by the cable bolt until failure is 48% lower than the energy E_1s determined for wire rope failure under static loading. Furthermore, cable bolt failure under dynamic loading occurred at an impact velocity of the combined ram and crosshead masses ranging within v_p = 1.4-1.5 m/s.

The paper presents the results of the experimental tests of Mg/Al bimetallic bars rolling process in classic and multi-radial modified round-oval-round passes. The bimetallic bar consist of magnesium core, grade AZ31 and aluminium outer layer, grade 1050A. The stocks were round bars with diameter 22.5 mm with an aluminium layer share of 28%. As a result of rolling in four passes, bars of a diameter of about 17 mm were obtained. A bimetallic feedstock was manufactured using an explosive welding method. The use of the designed arrangement of multi-radial modified stretching passes resulted in obtaining Mg/Al bimetallic bars with an uniform distribution of the cladding layer over the bar perimeter and high quality of shear strength between individual layers compared to Mg/Al bars obtained in the classic passes.

Pojemniki są ważnym elementem wyposażenia zabytkowego ogrodu. Kwiaty były uprawiane w donicach i misach już w czasach Homera. W ogrodach historycznych XVII, XVIII i XIX wieku pojemniki ustawiano w punktach, które chciano podkreślić, formowano z nich rzędy i rytmiczne kompozycje. Donice ustawiano nad brzegami zbiorników wodnych, na balustradach, tarasach i schodach.

In this study some of the experimental results of water shut-off treatments in oil and gas production wells were presented. The effect of water saturation of Miocene rocks of the Carpathian Foredeep on the relative permeability to gas was analyzed. Also, wide review of the worldwide publications from the point of view of the results obtained in water shut-off treatments in oil and gas formation was presented. Based on experimental results efficiency of relative permeability modification of sandstone from Szydłowiec to brine and nitrogen by four selected chemicals polymers and microgels was evaluated. Experimental results indicated that trend changes of permeability modification strongly depends on the fluid used in the RPM treatment. Moreover, efficiency of permeability modification to brine depends on flow rate of brine through the core - the lower brine flow rate the higher efficiency of the RPM treatment. RPM product number 1 caused significant loss of permeability to brine ca. 60% and slight permeability modification to gas ca. 18%. This permeability change to brine and gas was obtained by modification of formation wettability what affects well productivity. In the case of product number 2 which is based on microgels technology, also significant modification of selective permeability to brine was observed. Loss of permeability to brine was in the range of 65 to 90% while to gas ca. 50%.