Engineering Geology Characteristics of Zarani Dam Site (South East of Iran) Emphasis Seepage from Foundation and Abutments

Abstract

Embankment dam of Zarani in the Hormozgan province is located 35 km southeast of Minab. Studied area is located in the western end of the Makran subduction zone. The main regional faulting systems near the site, is Minab- Zandan-Palami right- handed thrust system. The purpose of this study was to identify the geology, engineering geology of reservoir area, and foundation and fulcrum of dam, scrutiny and analysis discontinuities of rock mass, to determine joints and fractures, determine the permeability of dam structure (foundation and fulcrum) based on the results lugeon test and finally, offer suggestions for cut off dam. The research method includes first gather basic information and general research, and then field investigations were done and finally were analyzed data by the Stereonet, Stereograph and Dips software. The result of lugeon test showed penetration depth in the right, middle and left side are 45, 45 and 50 respectively, the slope of shale - sandstone layers of site is near vertical and the dip direction is the east to northeast. This condition of site formation has cut off rule, but it cause to seepage on the right shore of reservoir. In the right shore of the reservoir, shale layers were dominant and have folded out by the Zendan faults and has changed trend of the layers, which caused cut off in this area. The left and right abutment of structure, three sets of discontinuities crosscut the rock mass, according to the layering in these categories are with discontinuities, make most of potentially space to escape water, but because of vertical layers, this space has not noticeable effect on seepage.