The construction of Latiyan Buttress Dam was finished in 1968. The result of dam instrumentation indicated that till July of 1970 the dam was in a suitable situation. However at that time vertical cracks were observed on the walls of buttress 10/11, for the first time. These cracks were located on both sides of the gate control room, which extend from the crest level down to the floor of control room. The rehabilitation operations were done by injection of epoxy into the crack openings in winter 1970, but it did not work properly and the cracks opened again in summer 1971. Measurement of opening and closing of cracks shows a cyclic loop behavior affected by seasonal variations in temperature. The latter seems to be the major cause of cracking. In this study finite element analysis of crack propagation has been done by use of Nonlinear Fracture Mechanics concepts and Smeared Crack Method. In this method it’s suggested that the crack will be replaced by a continuum with changeable physical properties. If the failure criterion is met, cracking takes place in the direction normal to the maximum principal stress. After cracking, the stiffness of concrete normal to the crack plane is reduced and concrete model becomes orthotropic. Therefore by propagation of crack in the structure the finite element mesh will not change while the material behavior relation changes. At first we find the distribution of temperature in the dam body by Heat Transfer Analysis for both summer and winter. Then by applying different static load combinations, the load combination that produce the crack is found. The result of static analysis demonstrates that applying the following load combination would cause high tensile stresses in the cracked region: Dam Weight + Hydrostatic Pressure + Summer Temperature Load + Lateral Pressure of Adjacent Blocks
By analyzing of the model under cyclic temperature loads it is concluded that after a while the results should become steady and increasing the loading cycles does not make major differences in the results. We can conclude that by applying static loads the crack pattern won’t propagate and the dam won’t get in danger. It means that to keep services of this dam it is not necessary to do rehabilitation operations to resist static loads and the dam is safe in the normal loading conditions.
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