In design stage of Karun-4 dam, fifty six FDT were performed as part of the in-situ testing programme to determine the moduli of the foundation rock mass. Creep behaviour and anisotropy properties of the rock mass were also detected. The results denote insufficiency amount of the moduli, whereas the remedy methods such as grouting in the rock mass of both sides evoke an increase in the moduli as well as the strength of the rock mass.
Pendant le stage preliminaire de Karun-4, cinquante six TDF etaient executes comme une partie du programme des essais en place afin de determiner les modules de la massive rocheuse de fondation. Les proprietes de l'anisotropie et le comportement incline de la massive rocheuse etaient aussi detectees. Les resultats signifient insuffisamment l'intensite des modules, tandis que les methodes de remede tel qu'injection de ciment dans la masse a deux cotes evoque un accroissement des modules ainsi qu'une augmentation a la resistance de la massive rocheuse.
In der phase der planung der Karun-4 talsperre, 56 FDT wurde als ein programm der in-situ untersuchung geleistet, um den modulitaets faktor der fondation des gesteins festzustellen. Das rutsehverhalten und anisotropische eigenschaften der gesteinsmasse wurde entdeckt Die ergebnisse zeigten ungenuegende modulitaet. Gegenueber dieses, die abhilfemetoden wie zementieren der beiden seiten erhoeht die modulitaet der gesteinsmasse sowie dessen bruchfestigkeit.
Karun-4 dam project envisages construction of a 205m high concrete dam on Karon river in Chaharmahal province to the south-west of Iran. Typical geology of the site has been brought out here to study the engineering properties of these rocks.
One of the problems in rock mechanics is the assessment of deformability of rock masses. Some methods are used for measuring in-situ the deformability and for determining the elastic material constants of rocks or of stiff soils.
In design stage of Karun-4 dam project. among various insitu testing methods, Flexible Dilatometer Test (FDT) was performed as part of this testing programme to determine the moduli of the foundation rock mass. Other in-situ tests such as Plate Load Jests (PLT) and Direct Shear Tests (DST) are also conducted to find the moduli and shear behaviour of the rock mass. Although FDT method has some limitations such as maximum. applied pressure and the scale of the rock mass in contact, in comparison with other methods like PLT, it is advantageous because of its easy access to the undisturbed rock mass in deeper zones. Beside that when compared with PLT, the dilatometer test offers several more advantages:
Reduced cost and increased operational facility enabling to perform several tests at various depths in a borehole.
Testing of the ground in a state as close as possible to natural mechanical and hydraulic conditions.
Possibility of detennining the anisotropy of the ground formatron
The range of deformation and Young's moduli measurable by the dilatometer extends from about 5 MPa to about 20 GPa (50 bars to 200.000 bars).
