Design criteria for rock foundation treatment in dam sites

1995. Design criteria for rock foundation treatment in dam sites : Gavoshan dam site, Iran / by Hamid Bagheri. - Delft : ITC, 1995. - 90 p. ; 30 cm. - ITC MSc-thesis. ABSTRACT, supervisor: Hack, thesis availability: ITC Library.

ABSTRACT

Over the past two centuries, a short period compared to that of the development of civil engineering, grouting has been used for improvement of the underground. In grouting, grout     is injected to the fissures, voids and cavities in soil and rock formations in order to seal them.

Nowadays grouting has a wide application in civil engineering works, but this research only deals with rock grouting in dam construction. Two types of rock grouting are predominantly carried out in dam sites:

* Curtain grouting, to reduce the permeability of the rock foundations.

* Consolidation grouting, to increase the strength of the rock formations.

The rock masses are never homogeneous they are jointed and fractured. When joints have connection with the reservoir area and down stream side, percolate water. Seepage can cause water loss, uplift force and hydrostatic pressure below the dam.

Discontinuities are different in size, extension and shape and ranging between very fine and extremely wide openings. Normally a grout curtain is not necessary for very narrowly     spaced discontinuities when seepage loss is negligible. For large openings, or a danger of erosion of filling materials of discontinuities and high water losses, sealing of the openings with grouting suspension is really necessary.

In consolidation grouting, all of the joints, fissures and voids must be grouted with a high strength grout in order to     reduce the rock deformability.

Different grout material and procedures have been used to get good results under different conditions. However designing and execution of grouting is still mostly on empirical basis. The aim of this research is to find the applicable design criteria for rock grouting with utilizing the available literature and case histories. And design the grout curtain and consolidation grouting for Gavoshan dam site which is located in the west of Iran in Kermanshah province.

In order to design and construct good grouting work, a lot of information about the rock foundation is necessary, that can be established by a comprehensive exploration and investigation. Site investigation should be able to provide the following information:

* Information about the geology of the site.

* Information of the permeability of rock foundation.