Deformation of rock foundations of high dams after filling the reservoirs

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1. Complex compressive and tensile deformations occur in the foundations of high dams, caused both by the loads from the installations and (to a greater extent) by the weight of water in the reservoirs. These have to be taken into account in the static calculations and model investigations into stability and stress of dams and their foundations. 2. In the relief and deconsolidation zones, the properties and behaviour of the rock masses differ substantially from those in the rock masses loaded and compressed from all sides outside these zones. In the first case, the rock mass must be considered as a system of blocks of different shape and size, interacting along the boundary surfaces and contacts. In the second case the rock mass is considered as an elastic medium, characterized by relatively high values of C, and capable of resisting the total and tensile stresses; fissuring, with the exception of individual breaks in continuity, is largely reduced to a minimum. 3. The detection and plotting of the deconsolidation zones of rock masses is one of the most important problems of prospecting and investigation of the foundations of high dams. 4. The principles governing the behaviour of rock foundations of high dams under the action of external loads, depending on a number of factors, have so far been little studied. Theoretical and experimental forecasts frequently diverge substantially from the actual.