The liquid and plastic limits (Atterberg limits) are of key importance in soil mechanics because they determine, in a simple way, the interaction between the solid and liquid phases in soils, and thus provide the possibility of classifying soils into groups with similar mechanical properties. It has been observed that all fine-grained soils have an almost equal undrained shear strength and hydraulic conductivity at the liquid limit as well as for the matrix suction. The results of the experimental tests of several researches have shown the values of the matrix suction at the liquid limit to be between 0.5 kPa and 7 kPa. The aim of the present study was to determine the matrix potential of fine-grained soils at the liquid limit by using the experimentally obtained thickness of the adsorbed water film on the external surfaces of clay minerals. The double-porosity model for the pore space geometry was considered as well as the assumption that, at equilibrium, the water in the clay mineral aggregates and macropores of fine-grained soils is in the same energy state. The obtained values of the matrix potential ranged from - 2.2 kPa to - 8.6 kPa, depending on the adopted value of the Hamaker constant for the soil-water system.
COBISS.SI-ID: 15986966
The method of sublevel coal extraction requires multi caving of the hanging wall layers, which are recompressed, and where each represent a hanging wall in sublevel stoping. Extensive stress and deformation changes in the surrounding area and in the mine represent a safety hazard for employees since the supporting system in the mine roadway could collapse. A numerical model, which allows for in-depth analyses of the geomechanical processes is broadly applicable and highly relevant for analyzing the intensity and the level of caving processes in sublevel coal mining, and for making realistic plans for coal excavation with worker safety in mind.
COBISS.SI-ID: 1215327
The assessment for realistic CO2-adsorption capacities of different rocks is important for understanding the processes associated with CO2 storage. This paper investigates the adsorption characteristics of rocks for CO2 by using a gravimetric method. The measurements were performed at 21oC with pressures from 1 up to 4 MPa. Sandstone (and clay with sand/sandstone) showed the largest adsorption capacity at 21o C. The highest amount of in situ CO2 contents in measured samples was 21.4 kg/t. The CO2 adsorption capacities were lower than past results in different coal samples. The results indicate that adsorption of CO2 into rocks may play an important role in storing CO2 in subsurface rock.
COBISS.SI-ID: 7007097
The objective of this paper is to present an alternative approach to the conventional level set methods for solving two-dimensional moving-boundary problems. A new approach is used to solve a convective transport equation for advancing the level set function in time. This new approach is based on the asymmetric meshless collocation method and the adaptive greedy algorithm. Numerical simulations are performed to verify the accuracy and stability of the new numerical scheme which is then applied to simulate a bubble that is moving, stretching and circulating in an ambient flow to demonstrate the performance of the new meshless approach.
COBISS.SI-ID: 5041761
A new method is presented for the self-noise estimation of a seismometer using a single, side-by-side, reference instrument and taking into consideration the misalignment in the orientation of both seismometers. The self-noise of seismometers is extracted directly from the measurements without using any information relating to the transfer functions. This procedure can be applied if the self-noise of the reference seismometer is well known and defined, or if the self-noise of the reference seismometer is sufficiently below the selfnoise of the tested instrument and can be neglected. The latter case applies to this study. An algorithm is also developed where we apply self-noise data in order to determine the orientation misalignment between two seismometers, which is then resolved in threedimensional space. This new method provides an estimate of the self-noise and can also be used to extract some parameters of the installed seismic system in comparison with the reference seismic system, such as generator constants and seismometer.
COBISS.SI-ID: 1165663