Engineering classification and index properties of the rocks at derbandi gomasbpan-suggested dam site

Abstract EN

This study concerns the ground conditions and the engineering properties of the rocks in Derbandi Gomasbpan (Gomasbpan valley), which was suggested to be a site for a dam construction.

The study emphasized on the qualitative engineering classifications and index properties of the existed rocks at the site as to be the dam foundation, their abutments and for the stability of the slopes, including the slopes of the dam embankments (when it is built from) during and after construction.

The Pila Spi Limestone which is one of the rock types and widely exposed at the site, was exceptionally, studied for its engineering behavior.

The geotechnical laboratory testing of Pila Spi limestone was carried out and the acquired data were used for its engineering classifications both, as an intact rock and as a rock mass.

The study results show that the general qualitative classification of this rock is rigid and high in mass strength, eventually, the rock was reliably evaluated for the dam foundation and its abutments.

The Gercus and Kolosh Formations which are predominantly composed of shale, which extensively, exposed at the dam site and most of the stream drainage-basin area.

The rocks at the dam site were studied in part for their mechanical properties, emphasized on their slake durability indexes and shale ratings.

The test results of the slake-durability and rating of the shale were variable in values, few tested samples showed, relatively, with very low rating.

The shale rating results were evaluated for the estimations of allowable slope angles of the dam embankment (construct from this shale) as a function of the shale ratings.

The allowable lift thicknesses and required compaction field densities of the shale for the embankment were also estimated.