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Seepage is a crucial factor in the design of dams as it can lead to failure if not controlled. This study delves into the numerical modeling of seepage and investigates the effects of different sealing systems on the foundation and body of earthen dams under steady flow conditions. The study explores various sealing conditions ranging from optimal to critical, which include clay blankets, drains, and clay curtains in the foundation. In general, the combined effects have been studied by combining all types of defined elements without considering their geometric dimensions. The study reveals that the different seepage reduction systems have significant effects on reducing the flow within the dam body and foundation. The trend of seepage discharge increases with height and reaches a maximum between 38 to 46 meters before decreasing again. The combination of a drain, clay blanket, and clay curtain proved to be the most effective in ensuring the dam's stability. The study shows that this combination can reduce the flow rate by an average of 83%, the seepage rate by an average of 15.5%, and the water head by an average of 9.5% at downstream of the dam. The results of this study suggest that the diversity in the type of flow seepage reduction systems has a significant effect on reducing the flow inside the dam body and foundation. This finding underscores the importance of considering the combined effects of different sealing systems to ensure the stability of the dam. [ABSTRACT FROM AUTHOR]

The present work reports on the preparation and investigation of the properties of composites based on acrylonitrile butadiene rubber (NBR) aimed for production of sealants in water supply networks carrying hot and cold potable water. The studies involve 12 NBR-based composites. A conventional, semi-efficient and efficient sulphur-vulcanization system is used for four of the composites. A vulcanizing agent, dicumyl peroxide, was used in the other eight composites. The results obtained show that the type of the vulcanization system used has a significant impact both on the vulcanization characteristics of the investigated rubber compounds and on the mechanical properties of their vulcanizates. The comparison of the results obtained and the requirements of standard EN 681-1:1996 referring to the mechanical properties of the elastomer composites used for production of sealants for pipes carrying hot and cold potable water reveal that composition P-10 is the most suitable for the purpose. The microbiological characteristics of the water in contact with the composites indicate that no bacterial growth occurs in the samples tested as a result of this contact. The latter does not lead to a change of the organoleptic parameters as well. Higher values of heavy metals, nitrates or nitrites are not observed. [ABSTRACT FROM AUTHOR]

Petroleum and natural gas still have their place among the most important resources in many industrial areas. Their global consumption influences an increasing demand on the quality of drilling works and the efficiency of extraction. Nonetheless, even in this field of human activity, we can encounter exceptional events and accidents. One of the most serious kinds of accidents during exploration is the so called open eruption of extracted medium. The specific case of this accident is an open eruption caused by drilling tools when a working crew is not capable of securing drilling workplace. In order to solve this emergency situation, Main Mining Rescue Station Hodonin (HBZS Hodonin), in cooperation with researchers from Faculty of Mining and Geology at VSB - Technical University of Ostrava, designed and developed specialised apparatus DPRP (Drill Pipe Rescue Press), working designation FIB- 1. This apparatus enables the liquidation of eruption by pressing the drilling pipe. The residual crack, which remains following the pressing, must be eliminated by sealing materials. This paper reviews the testing of sealing elements (materials), designed by our team, in residual crack of circle shape with help of hydraulic press MTS 816 Rock Test System. [ABSTRACT FROM AUTHOR]

The influence of various stabilizers on the properties of rubber based on silicone rubber SKTV is studied. It is established that the use of the Ca/Zn stabilizer in the resin composition makes it possible to increase thermal resistance and physico-mechanical characteristics of the rubber used to make sealing elements in the automotive industry. [ABSTRACT FROM AUTHOR]

The tribomechanical functionality of a layered elastomeric composite in the form of a rubber substrate with a thin, nanoscale-thickness carbon (diamond-like) coating deposited on it was investigated. By the methods of dynamic contact indentation and tribotesting, it is established that, with increase in coating thickness, the Shore A hardness, viscosity, and relaxation time of the composite increase if the static and sliding friction coefficients decrease. The coating changes the classic wear mechanism of rubber from destruction by rolling down towards the less intense fatigue wear, which is characteristic of materials with a low friction coefficient. By calculating, it is shown that a change in coating thickness leads to a significant change in its stiffness from an insignificant flexural stiffness of membrane at h = 22 nm (in this case, the distribution of displacements practically coincides with deflection of an elastic half-space) to that of an almost nondeformable plate at h = 180 nm. [ABSTRACT FROM AUTHOR]