Mechanical properties of soils in internal waste bank of lignite mines and their primary characteristics

Abstract

The modern development of urban areas is related to, among others, the location of industrial facilities on the outskirts of cities. More and more often, commercial buildings are founded on areas that have not been used for construction so far. Such areas include, among others: reclaimed lignite mine banks in the Konin region. The man-made soil is a chaotic mixture of fragments of glacial tills and Pliocene clays, often exceeding 20 m in thickness, which is naturally consolidated over time. Due to the method of formation of the embankment, despite the fact that banks are made of natural soil, their strength and deformation characteristics clearly differ from those characteristic of lithologically similar soils deposited as a result of geological processes. In this case, the use of a standard test approach may overestimate the strength and stiffness of the soil. Due to the complex structure of the bank in-situ tests were used for geotechnical exploration: CPTU and FVT, as well as laboratory tests in a triaxial apparatus and an oedometer. The results were compared with the results of studies conducted in similar naturally deposited soils. The obtained results provide valuable geotechnical characteristics of the embankment soil, which in its large fragments is built of natural soil clasts. The obtained results indicate a relatively small change in the geotechnical properties of the soils incorporated into the embankment within individual clasts of the natural soil (on a local scale) and a clear deterioration in the scale of the entire embankment, treated as the impact zone of building structures.