Stateczność nawodnionej skarpy z mieszanki popiołowo-żużlowej

Artykuł przedstawia wyniki badań modelu fizycznego i obliczeń numerycznych dotyczących stateczności skarpy odwodnej nasypu. Model fizyczny nasypu hydrotechnicznego wybudowano w skali zmniejszonej w korycie hydraulicznym, wewnątrz którego zamontowano urządzenia umożliwiające swobodną regulację poziomu wody górnej i dolnej, a także rurki piezometryczne z elektronicznym pomiarem poziomu wody wewnątrz modelu. Wstępnie w badaniach laboratoryjnych określono podstawowe parametry fizyczne i mechaniczne gruntu niezbędne do uformowania nasypu modelowego. Oznaczone w laboratorium parametry gęstości, kąta tarcia wewnętrznego i kohezji oraz poziomy piezometryczne z badań modelowych zostały wprowadzone do obliczeń numerycznych w celu określenia współczynnika stateczności dla skarpy odwodnej. Obliczenia wykonano metodą Bishopa dla sześciu schematów obliczeniowych przy zmiennym położeniu krzywej filtracji w korpusie nasypu. Wyniki przeprowadzonych prac wskazują na zależność pomiędzy położeniem krzywej depresji, parametrami geotechnicznymi nawodnionej mieszanki popiołowo-żużlowej a uzyskiwaną wartością współczynnika stateczności.

Furnace waste that is produced in power plants is, among other things, ash-slag mixture. Considering high production of this material nowadays it is used in different fields of engineering as a valuable anthropogenic soil. Good compaction parameters of this type of waste are the reason for its often usage in forming embankments (also hydrotechnical). Ash-slag mixture can be used for these types of constructions providing that it will be carefully protected from water influence. Inappropriately selected design parameters can lead to instability of structures' slopes.The paper presents results from tests on the physical model and numerical calculations concerning a stability of riverside slope of embankment. The physical model of hydrotechnical embankment was built in a half-technical scale in hydrotechnical trough, inside of which there were devices that enabled free control of water levels installed, as well as piezometer tubes with electronic measurement of water levels inside the model. Tested material came from Skawina Power Plant. It was furnace waste from process of burning hard coal, which is the main fuel of the power plant. Initially, basic physical and mechanical parameters of tested soil necessary for forming the model embankment were determined in laboratory tests. Determined in laboratory parameters of density, angle of internal friction and cohesion as well as piezometric levels from model tests were used for carrying out numeric calculations in order to determine a safety factor of riverside slope. Calculations were carried out using Bishop's method for six calculation schemes with different retention levels of water as well as with changing position of filtration curve in the embankment body. Tests results indicate that there is a relation between position of filtration curve, geotechnical parameters of saturated ash-slag mixture and obtained values of safety factors. Observation and measuring were carried out during water level rising as well as during keeping target water level at 50 cm. The riverside slope was also controlled at quick lowering of the water level. Flow pressure that occurs at that time did not contribute to slope instability or to damages in the riverside slope, despite the inclination 1 : 1.5. Tests and calculations gave results that were concordant in regard to stability of the riverside model slope at every retention level. Model tests can distinctly verify stability calculations based on geotechnical parameters that were determined in laboratory.