PIPING IN A CAVE-FORMING CLAYSTONE-INJANA FORMATION, KARBALA – NAJAF AREA

Abstract

A Cave-forming claystone bed, just below Dibdiba Formation has been studied. This bed ranges in thickness from 6 – 10 m or more, and has a considerable extension (about 180 Km) along Tar Al-Najaf and Tar Al-Sayyed.
The study indicates that one of the interesting geological hazard phenomenon (piping) is well developed in that bed. It is clear that the main reason for the caving in the claystone bed is the water erosion, particularly along the remarkable joints (two set of joints), the north-south and east-west direction.
A well defined irregular holes due to piping has been noticed in this bed, they are of different shapes and sizes that reach (11.0 x 1.25 x 8.0 m) dimensions. These holes are scattered on a small exposed plateau of the cave-forming claystone. This bed has been exposed due to backward erosion of the overlying Dibdiba Formation. The study also indicates that piping phenomenon should be taken in consideration for any heavy construction on Karbala – Najaf plateau, and that the cave-forming claystone represents a uniform quite fluvial environment.