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This paper presents some results of the laboratory tests on the time-dependent behaviour of three types of sandstone. Research into the rheological properties of rocks is mostly done under static (quasistatic) loading. In nature, however, rocks are also often subjected to cyclic (vibration) loading as a result of vibrations from traffic or the propagation of seismic waves due to, for example, earthquakes, rock bursts, blasting operations and such like. On this account, the research presented is focused on the study of rheological rock properties during vibration (cyclic) loading.The tests of the rheological properties of a cyclic load were conducted both in creep regime and in relaxation regime, at various levels of average load or strain and for various parameters of vibration (frequency, amplitude).The measured values of different parameter settings were compared and evaluated so that it was possible to set the dependence of cyclical rock loading in the rheological regime. For the purpose of the comparison of rock behavior during vibration and static loading, other tests were also carried out.The results of the research show that, in the course of cyclical loading, the rock rheological properties depend, to a significant extent, on the parameters of this loading, especially the amplitude and frequency.

Abstract. This article presents a method for the experimental measurement of specific fracture energy and surface tension of a brittle materials in a powder form. This work is focused on testing a method on the mineral, almandine. A hydraulic press was used in the experiment to crush powder particles, and statistical evaluation was used to analyze the change in the powder surface. The powder was subject to various conditions during crushing. The crushing was performed both in air and in water. It was done at three different compression speeds, namely 15.8 MPa/s, 3.95 MPa/s and 2.25 MPa/s. The experimental results showed measurable differences in the specific fracture energy values in the presented regimes.

Technology of a composite material of silicon nano-particles (99.999 w% for semiconductors) arranged densely in a metal tin matrix (99.7 w%) is presented in the present paper. The main motivation for the technology development is an endeavor to prepare a nano-composite material in which semiconductor particles are crowded densely by applying high pressure in a metal matrix. In the above arrangement, a coexistence of very narrow mesh nanostructure of a tin matrix with dispersed nanoparicles of silicon is involved. With the high level of volume density of nanoparticles, the surface interface between metal and semiconductor attains an extraordinarily large size. Thanks to this fact, a significant enhancement of the volume rate of the transitional Shottky's zone between metal tin and semiconductive silicon has been reached. Based on preliminary measurements, the abovementioned structure is characterized by an active influence on material behavior in the area of temperature dependence of resistivity which cannot be explained by mere superposition of parallel currents in two independent components: silicon and tin.