Pęcznienie skał senońskich w przełomowym odcinku Wisły środkowej jego inżyniersko-geologiczne znaczenie

Witold Cezariusz Kowalski

Abstract


SWELLING OF SENONIAN ROCKS IN THE REARCH AREA OF THE MIDDLE VISTULA AND ITS ENGINEERING GEOLOGICAL SIGNIFICANCE

Summary
The valley slopes of the reach sector of Middle Vistula river consist of strongly fractured rocks of Upper Cretaceous. Although these rocks are practically completely impermeable, due to their fracturings making an uniform system of fissures perfectly connected with each other – water might easily flow through these fissures.
However, the previous observation of occurrence of most fracturings above the zone of complete water saturation of rock massif and their disappearance in this zone as well as examination of presence of variously swelling clay minerals in the Senonian rocks allowed for assumption that these rocks swell i.e. magnify their volume when they absorb water.
The study of water saturation and drying the samples of Senonian siliceous marl of 10.23% montmorillonite and 17.35% illite contents as well as opoka marl of 14.16% montmorillonite and 6.35% illite contents permit to draw the following conclusions:
1 – the above mentioned Senonian rocks occurring above the water saturation zone in natural dry state are portially fractured due to the contraction;
2 – these rocks after water saturation swell with at least, partial narrowing of the exist fissures;
3 – maximum swelling is to be seen within the rocks of great contents of clay minerals;
4 – swelling appearance of the Senonian rocks diminishes the water permeability of the Senonian massif and should be taken into consideration during forecasting of water decreases of an eventual basin;
5 – determination of quantitative influence of this phenomenon requires the future study.

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