For better understanding of materials behavior subjected to thermal fatigue of work rolls used in hot rolling mill, two thermal fatigue tests were developed. Tests were performed using Gleeble 1500D thermo-mechanical simulator. The first test was applied for the testing of thermal fatigue resistance of work rolls used in common rolling conditions. The average cracks length and the crack density of the specimens were established at varying test temperatures and the number of thermal fatigue cycles. The second test enabled the simulation of the thermal loading of the work rolls during a rolling mill stall. The growth of stall band firecracks after different cooling condition of the work rolls is presented.
F.04 Increase of the technological level
COBISS.SI-ID: 1487967With the development of information technology, the possibilities of detail geomechanical analysis with the application of numerical methods have become an indispensable design tool for underground structures in different ground. In the practical applications we often had difficulties to determine input parameters and boundary conditions. Too little awareness of the influence on analysis results of the latter can easily lead us to an incorrect interpretation of the performed analyses and consequently inappropriate input parameters for underground structure design. With the purpose to research the influences of input parameters on ground deformation and structural forces in lining results, several 2D and 3D parametric analyses with Midas GTS 2013 and Midas GTS NX have been performed. The influence of boundary conditions, mesh coarseness and initial stress on calculated movement and stresses in ground-support system has been researched. 2D and 3D modelling procedures with different elasto-plastic constitutive models have been verified on the case study of two tunnels, which were constructed in different geotechnical conditions. A comparison has been made between the results of 2D and 3D analyses by using the Mohr Coulomb and Hardening Soil model. The calculated deformation values have been compared with measurements that were carried out during construction of two road tunnels.
F.16 Improvements to an existing information system/databases
COBISS.SI-ID: 1503327The presentation considers the approach of active soil pressure determination of confined deep excavations during excavation pit works, locally unprotected excavations constructing retaining structures, canalization tunnels and protecting deep excavations when outer stability of excavations constructing deep RC diaphragms is estimated. The presented procedure gives considering ψ=Φ realistic results what is verified with comparative analyses using FEM. Smaller dilatation coefficients should be used for practical use i.e. ψ=Φ/2 depending on properties of individual soils.
F.09 Development of a new technological process or technology
COBISS.SI-ID: 17885974In the construction of underground structures are always present risks due to unexpected ground conditions, the most basic goal is to provide stability in the planning and construction phase. Due to influence of parameters, which are known as random variables, is expedient to develop risk analysis with probabilistic approach, which enable to research the reliability of groups of data from geotechnical investigations and safety against the failure. It is also important to have carefully determined contract relation and obligations between the client and the contractor. In this article there will be represented risk assessment for basic stability reliability of underground structure and general overview of valid legislation in the Republic of Slovenia for the field of structure construction, set of laws, international recommendations and guidelines and law harmonisation at construction of the underground structures and divisions of risk between the subscriber and the contractor.
F.09 Development of a new technological process or technology
COBISS.SI-ID: 1488223The investigations described in this paper were performed in order to determine whether the concentrations of total suspended solids (TSS) in the Drava River, Slovenia, measured indirectly with optical sensors can be used to determine the amount and particle size of the suspended solids that can settle in stagnant water. The possibility of continuous monitoring of the TSS concentrations would allow a more reliable estimate of the amount of sediment in the accumulation lake of the planned, pumped-storage, hydroelectric power plant into which the water from the Drava River will be pumped. Therefore, during a period of one year, 90 water samples were taken directly at the optical sensors. The amount of sediments and their mineral and chemical compositions were investigated, and particle size analyses were made in 15 samples. Microbiological parameters, which included a determination of the amount of phytoplankton, zooplankton, bacteria, fungi and organic debris, were investigated in all the water samples, and the temperature and pH of the water were measured at the time when the samples were collected. The comparison of the parameters examined with the TSS concentrations showed that these concentrations can serve as a very good estimate of the amount of particles settled in the standing water, as well as of their size. These correlations are clearly expressed in the cases where the amounts of phytoplankton and organic debris in the water are low.
F.09 Development of a new technological process or technology
COBISS.SI-ID: 17860630