Jerzy Janusz, Wojciech Janusz - Monographic Series No 9
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Inwestigations of reactions of water storage reservoirs to changes of acting pressure load
Every structure is subject to geometrical changes correlated to variations in acting pressure loads. Vectors describing shifts of discrete points established on the structure can be determined on the basis of measurements of a control network, which contains discrete points of the structure as well as points in its vicinity. Such shift vectors, in conjunction with pressure load information, may serve for calculations of coefficients which characterize the susceptibility of the construction to pressures acting on it.
This work describes the technology employed in geometrical monitoring of the embankment and water inlet/outlet building of the largest in Poland storage pumping power plant. Here, shifts occur as a result of daily changes in water level in the reservoir – of app. 14 mln m3.
The following vectors and coefficients have been derived from surveys of horizontal and vertical control networks covering the embankment and water inlet/outlet building, performed under high and low water levels:
- horizontal and vertical shifts of points established on structures under investigation,
- model of geometrical changes (of scale and inclination) of these structures,
- coefficients of changes of scale and inclination of the structures per unit of change of water level,
- divergence of shift vectors from the model, pointing out regions of the embankment of lesser/greater susceptibility to pressure changes (change in water level),
- shifts of the natural terrain in vicinity of the water reservoir.
Values mentioned above have been observed once a year since 2001, demonstrating changes within the range of error of measurement. This indicates a persistent resistance of the man-made land bank and reinforcedconcrete inlet/outlet building to changes in pressure.
Future surveys, such as have been described, are expected to serve as an important safety precaution – changes of values of shift vectors and individual shift vector divergence from the model can indicate altered vulnerability of the embankment and water outlet construction and should alert of heightened risk of operation of the facility.