Determination of the geomechanical characteristics of riprap materials in Gelingüllü (Yozgat) Dam

Riprap is a cover layer that is placed to protect the upstream slope of the earth-dwelling dams. The physical and mechanical properties of the rocks to be used as riprap material in the dam body should have certain limit values. Mineralogical, physical and mechanical properties of the rocks change due to the physical and chemical degradation effects and the physical and mechanical properties of the rocks which are within the limits for riprap material initially can go beyond these limits. The values outside the boundaries constitute problems for the dam. The continental climate is dominant in the region, and the rocks used as riprap are intense frost-dissolving effect. In this study, geological, physical and mechanical properties of rocks used as riprap material in Gelingüllü dam body have been investigated. It has been understood that the marginal zones of the blocks, and especially the blocks of the aqueous zones (A, B, C), show more mating, sericitization, hydrobiotization and microcracking. Blocks in the A zone rounded by wave action and weathering. The average values of the dry density, the water absorption and the compressive strength of the blocks in all zones, are within acceptable limits. However, it was observed that the engineering parameters of some blocks in A, B, and C zones affected by the dam water are out of the acceptable limits. All engineering parameters remained within the acceptable limits in dry zone (D). Rocks in the A, B and C zones have higher porosity values than D zone. The increase in porosity can enhance the impact of wetting-drying and freezing-thawing on the riprap blocks. This will accelerate the degradation and weakening of the blocks. Key words: Riprap, Gelingüllü Dam, earth dam, granite, Yozgat