Abstract
In Lithuania, surface moraine loam, clay and other lithologic varieties with low permeability take around 60% of the territory. Roads, railway tracks, bridges, dumps intended for keeping waste of different level of danger and other overground structures are built in these areas. Moraine formations with low water permeability become the foundation for earth bank, roads, bridge supports, dumps and other engineering structures. Through these foundations water filtration, infiltration, movement of capillary water and evaporation to the atmosphere continue during the entire period of operation. In wintertime, the volumetric changes of water, contained and freezing in these soils, and water migration in soil towards the surface of freezing determine deformations of foundations or road surface and the occurrence of frost cracks. All the mentioned water migration processes in the layers take place in various directions and in different intensity. This determines the change in geomechanical and geofiltration properties of foundation soils. Foundation soil deformations are likely also due to the processes of drying, bloating and filtration of clayey soils. Thus, the goal of the present work is to evaluate the evolution of filtration features and evaporation intensity of moraine loam in time. The continuous duration of laboratory investigations was over 10 months. For filtration, the filtrometer was used containing the Proctor Standard moulds, water deaeration device and pressure measuring stand with three tubes of different diameter (piezometers). Water and air temperature and relative humidity of the laboratory were measured during each experiment.
Highlights
Filtration features of moraine loams in Lithuania, especially occurring at the surface, are subject to change
Moraine loam from the middle Pleistocene of quaternary of Medininkai (Lithuania) suite was taken from the excavation near the Vilnius Airport, where a road was being built
The essence of the performed experiments is that two processes – filtration from below and water evaporation from the surface – proceeded in loam simultaneously; only during the first experiment, the sample surface was covered with the perforated plate and steel gauze, and during the second one sample surface was uncovered
Summary
Filtration features of moraine loams in Lithuania, especially occurring at the surface, are subject to change. Geofiltration studies in situ were carried out in various regions of Lithuania (Dobkevičius et al 1988; Klizas 1993) The majority of these studies were performed in the north of Lithuania – the karst regions in Biržai and Pasvalys Districts. In these areas, moraine loam at the surface covers the Devonian sulphate carbonate thickening, where at the moment intense karst processes and sinkhole formation of the surface are observed. Filtration studies of solids with low permeability in this region were carried out with clays, loams, clayey marls, dolomites and chalk-stones of the Quaternary and Upper Devonian age, using the filtrometer LITA-5, designed by Klizas and Miksys (1985). Studies of changes in filtration characteristics of clayey solids with low permeability are carried out in different directions
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