Seismic stability of roundhead buttress dams

Abstract

Roundhead buttress dams, being one of the economic types of lightweight concrete dams, are often constructed in regions with high seismic activity. Despite the fact that many studies in the USSR and abroad (for example. [1][2][3][4][5][6]) are devoted to an investigation of the seismic stability of these structures, the elaboration of such problems as the effect of the three-dimensional behavior of the dam, yielding of the foundation, character of the seismic load, and. finally, the construction characteristics of a particular type of dam in relation to its seismic stability is far from complete.It is necessary to note that the existing methods of investigation [2,3,4,7] do not permit a complete consideration of the entire set of factors affecting the behavior of dams under dynamic loads. We used an experimental method of investigation on physical models which permits taking into consideration the characteristics of the work of the complex structure of high concrete dams.The experiments were of a dam with a height of 100 m and section width of 25.6 m ( Fig. 1) made on models to a scale of 1 : 200 under conditions of an empty reservoir. The seismic load was simulated as the magnitudes of reduced seismic accelerations WI = ktg and reproduced in two forms: seismic shock of forward direction(type I load) y=A for t<0,reproduced by means of a seismic platform equipped with an instantaneous-action hydraulic disrupter, and a seismic load of the traveling-wave type (type!I load) propagating in the mass of the model foundation with the shock assigned on its free surface. The accelerogram of this load, recorded at a point near the base of the model buttress, and its spectrum are given in Fig. 2a.