The opening of the contact joint between the concrete and rock in the zone of the upstream face of the bed sections of the Sayano-Shushenskoe dam, which was noted during the filling of the reservoir, continues to increase ( Fig. 1, data obtained by the Hydraulic Structures Laboratory at the Sayano-Shushenskoe hydroelectric plant). The maximum joint opening was observed in sections 18 and 45, which are located near the shoreline slope, and the minimum opening in key section 33. Variations in the opening of the contact joint for all sections, excluding section 33, have a clearly expressed seasonal character.Basic factors governing the opening of the contact joint in high gravity dams are rather well understood [1][2][3][4]. A tension zone may be forming beneath the upstream face of the dam as a result of load action on the structure and its rock bed. Tensile stresses a x virtually always develop along vertical platforms, while stresses cry develop along horizontal platforms only under certain conditions. The tensile stresses ay do not develop when they are completely compensated by the vertical component of the active loads, or when an additional store of compression is released at the contact by special measures taken during the dam's construction [5].The stage construction and monolithizing of the structure during the annual rise in the headrace level exert a significant influence on the stress--strain state of the concrete-rock contact of an arch-gravity dam.Computational and model studies conducted at the V. E. Vedeneev All-Union Scientific-Research Institute of Hydraulic Engineering with consideration of the actual stage construction of the Sayano-Shushenskoe Dam predict the development of tensile stresses of up to 2 MPa in the rock bed in the zone of the upstream face of the channel sections as the reservoir is filled to the normal operating level. Monolithizing of the Sayano-Shushenskoe Dam during its construction was carried out annually with seasonal drawdown of the reservoir in the winter-spring period with rather accurate observance of design requirements regarding the temperature state of the concrete masses; this ensured the combined action of the dam's columns. The behavior of the grouted intercolumn and intersectional joints, the character of variation of the relative deformations, as measured in the monolithic concrete and in the section of concrete with the joint [6], the displacements of the structure, and the deformations (bed settlements and tilting of the dam) suggest the monolithic character of the Sayano-Shushenskoe Dam~The monolithizing that was carried out has caused, among other things, "bridging" of the dam on the shoreline slopes and the appearance of an additional retaining moment, which prevent the tilting and deflection of the dam's channel sections. Neither of these factors make it possible to trace the sections freely beyond the depressions of the reservoir channel, which are caused by increasing pressure on its water column with increasing headrace level and which are developed by ...
out and the curves of their distributions with a determination of the design indices of the required probability are plotted. A correspondence of the statistical characteristics of the hydrological series (par. i) and hydrologlcal-morphological (or morphological, par. 3) series will not be observed. This is determined by the fact that the time series of the hydrological-morphological parameters (par. 3) cannot be obtained by linear transformations of the initial random sequence, which a hydrological series during a long-term period is (par. i), since the relations between the characteristics composing the series being compared are nonlinear. For example, the Saint Venant equation for unsteady flow in open channels is nonlinear.
The construction and operation of hydro developments are accompanied by technogenic effects and processes arising and developing in the foundation masses. The state of these masses established over the course o1 centuries undergoes serious changes in a comparatively brief time. The main factor determining the characteristics of the behavior of rock foundations of hydraulic structures and the extent and consequences of the technogenic effect on them is the seepage flow forming in the foundation from the time of filling the reservoir. For calculating the stress--strain state of the rock foundation, determining the characteristics of seepage processes occurring in its mass, evaluating the interaction of the dam and rock mass, and determining the deformations of the reservoir banks, it is necessary to correctly determine the size of the active region of the foundation and level of the force effect of the seepage flow in the indicated region.Calculation of the force effect of a reservoir and seepage flow on concrete dams and their rock foundations is carried out in conformity with the building codes SNiP 11-16-76 and SNiP 11-54-77. The calculated settlements of dam foundations, as the results of onsite observations show, is 1.5-2 times less than those actually observed. This indicates imperfection of the calculation scheme of permeable foundations. In our opinion, the calculation scheme should be refined with respect to the following main positions.First, it is necessary to more completely take into account the force factors caused by the seepage flow in the mass of the fractured foundation. In addition to uplifting forces, which occur in bank masses during their primary wetting, it is necessary to introduce into the calculation:The seepage forces, which are distributed in the bulk of the permeable mass in conformity with the law of distribution in the same mass of the gradient of the head I(x, y, z) and coefficient of the effective area of action of the seepage forces a2(x, y, z). For a certain band of the flow with length L and cross-sectional area to(L) the expression for the sum of the seepage forces has the following form:L where p is the water density; g is the acceleration of gravity; The seepage compressive (SC) forces which occur due to the existing piezometric head in the permeable foundation mass. If, for example, the rock mass is represented as a set of individual elastic impermeable cubic blocks with side a, then its permeability will be determined only by fractures. With an increase of the piezometric head in some region of the mass by the quantity ~d-/, each block due to all-around compression on the faces, will reduce the linear dimensions by the amount Aa. The opening b of each fracture will increase by this same amount (fib = Z~a).With consideration of the coefficient of the effective area of action of the seepage forces, each block is compressed not over the entire area of its faces but over a part of it. Then the decrease of the linear dimensions of each block will bewhere E, ~, are the modulus of ...
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