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Thank you my friend for your invitation,,,The effects of any internal hydrostatic pressures in arch dams,therefore, will be distributed between both vertical and horizontal elements. A recent analysis of these effects on an arch dam of moderate height showed a stress change of approximately 5 percent of the allowable stress. The capability of analyzing the effects of internal hydrostatic pressure has not been incorporated as a regular part of the analysis because of the minor change in stress.The internal pressure distribution through the foundation depends on depth of drains, grout curtain,rock porosity, jointing, faulting, and any other geologic features that may modify the flow. Determination of such pressure distributions can be made from flow nets computed by several methods including two- and three-dimensional physical models,two- and three-dimensional finite element models, and electric analogs. the An arch dam should be constructed of concrete that meets the design criteria for strength, durability, permeability, and other required properties. Because of the sustained loading generally associated with them, the concrete properties used for the analyses of static loading conditions should include the effects of creep.Properties of concrete vary with age, the type of cement, aggregates, and other ingredients, as well as their proportions in the mix [3]. Since different concretes, gain strength at different rates, measurements must be made of specimens of sufficient age to permit evaluation of ultimate strengths. Although the concrete mix is usually designed only for compressive strength, appropriate tests should be made to determine the tensile and shear strength values. The mix should be proportioned to produce LOADS Factors to be considered as contributing to the loading combinations for an arch dam are: (1) reservoir and tailwater loads, (2) temperature, (3) internal hydrostatic pressure, (4) dead weight, (5) ice, (6) silt, and (7) earthquake. Such factors as dead weight and static water loads can be calculated accurately. Others such as earthquake, temperature, ice, silt, and internal hydrostatic pressures must be predicted on the basis of assumptions of varying reliability.
