Unbound bearing layers have a distinct weakness that they are not capable of bearing tensile stresses in a horizontal plane. This results in plastic deformations that transmit on the surface of the pavement as cracks and ruts as a consequence. Despite the transformation of natural gravel and sand materials and added binders, vertical deformations of the pavement cannot be avoided. These are the consequence of excessive horizontal tensions in detached layers of the pavement construction, especially when overloading or in the case of deteriorated hydro-geologic conditions. Bound layers, combined with geocells, represent an effective system of pavement structure that guarantees permanent elasticity, flexibility and adequate bearing strength of the construction itself. Recent research has shown the advantage of using rigid geocells, which was also confirmed by the results of numerical modeling. Rigid geocells were also used in the test field. Numerical modelling and experimental analysis showed a crucial improvement of the bearing strength and reduction of deformation.
B.04 Guest lecture
COBISS.SI-ID: 20563734The results of tests performed in the laboratory on a flexible pavement structure subjected to simulated traffic loadings are presented. The aim of these tests was to help in practical applications in road design, so that the actual in-situ stress conditions and road traffic loads had to be adequately simulated. A new testing device known as a Traffic Load Simulator (TLS) has been constructed at the Slovenian National Building and Civil Engineering Institute (ZAG) for this purpose. In contrast to other similar experimental research methods, the TLS introduces synchronized vertical and horizontal cyclic loads which take into the account the specific characteristics of traffic loading, resulting in vertical and horizontal normal stresses as well as non-zero shear stress values. The latter cause rotation of the principal stress axis, which typically occurs during traffic loadings. The impact of traffic loading upon the development of rutting in the pavement structure is also presented.
F.23 Development of new system-wide, normative and programme solutions, and methods
COBISS.SI-ID: 2345063The effects of climate on soil strength as well as pavement dependence on climate, soil type, drainage and depth of ground water table, was considered. Most investigations can be divided into two main groups regarding to the effect on pavement strength: - Determining moisture and temperature effect on strength - Determining freeze-thaw cycle effect on pavement strength. Moisture content and temperature variations change the deformation properties of unbound material, which leads to variations of permanent deformation. Pavement stiffness rapidly decreases during spring thaw, which causes large settlements, while during freezing no changes in settlement or swelling can be observed. However spring thawing and snow melting can increase water content in base or sub base layer, which also leads to reduction of pavement strength, decreasing dry density and increasing the porosity.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 21194006The Velenje Coal Mine is causing subsidence of the surface of the mine pits by excavation of lignite with using longwall mining method. The Velenje Coal Mine - VCM's system of exploitation area observation is complex and can be classified as an extended geodetic monitoring system. With the extended geodetic monitoring system, the surface movements and deformations are observed on over 300 measurement points in mining area and it vicinity. The extended VCM geodetic monitoring system is constantly upgraded with new measurements and the latest measuring equipment. New observation network is established above longwall "-80 C" to monitor formation of subsidence. Observation network of the mine is measured by terrestrial measurements (TPS), GPS measurement and geometric leveling. Using drone subsidence is observed with use of aerophotogrammetry.
B.04 Guest lecture
COBISS.SI-ID: 1688159In underground coal mining engineering one of important tasks is to monitor, predict and managing the surface subsidence due to underground coal excavation. The impact of underground mining excavation reflects as subsidence of the overlying strata and the formation of surface depressions soon after excavation. The surface subsidence is one of many natural processes, which exhibit a progression from small beginnings that accelerates and approaches a climax over time. When a detailed data is lacking, a logistic function is often used. In this paper the analysis of the surface subsidence above longwall -80C in Velenje Coal Mine by using a modified sigmoid function (surrogate of logistic function), with common āSā shape, is introduced.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1688415