investigating the effect of initial values of lozenge and hydraulic gradient on the process of dissolution of gypsum located behind dams (case study of marash dam)

In order to optimally design earthen dams, it is inevitable to know the characteristics of its construction, including geological and geotechnical characteristics, as well as awareness of behaviors such as permeability and bedrock permeability changes during water intake and long-term exploitation of the dam reservoir. when the stone bed of the dam construction consists of materials containing gypsum and anhydrite, then these materials will last longer against the continuation of anti-flow. in the study of hazdar, the influence of the primary permeability values of the sedang-basdter of merash dam construction, which consists of joints containing gypsum and anhydrite, and hydraulic gradient values on the speed and process of the expansion of the joint, along with the dissolution rate of materials containing gypsum and anhydrite, has been investigated. the amount of expansion of each joint for the duration of a dam is calculated and considering the amount of hydraulic gradient drop in the body of the dam and manat with gypsum, the water loss rate of the dam is evaluated. the results obtained from the circulation test with the hydraulic gradient find that in the length of the water flow path, the rate of increase in the diameter of the joint decreases gradually. also, along the length of the water flow, in the places where there is purer gypsum, the rate of increase in the diameter of the seams is higher than the rest.