HISTORY OF MOSUL DAM AND ITS FOUNDATION

Mosul Dam is considered one of the most dangerous dams in the world. This project is an earth fill embankment with clay core located on the river Tigris north of Iraq about ۶۰ km northwest of Mosul city. The dam is ۱۱۳ m high, ۱۰ m wide in its crest and ۳۶۵۰ m long including the spillway. The dam was designed to impound ۱۱.۱۱ billion cubic meters. This scheme is a multipurpose dam to provide water for irrigation, hydropower generation, and flood control. From a geological standpoint, the location of the dam site was built on a double plunging anticline and problematic foundation. The rocks of the site are mainly consisting of brecciated and highly karstified gypsum/anhydrite, limestone, marl, and conglomerates in which gypsums are the main component as a cementing material. This has caused several problems during the construction, impounding, and operation of the dam. Since the first impounding of the reservoir, seepage of water was noticed due to the dissolution of gypsum beds beneath the foundation of the dam. To mitigate the seepage, plenty of grouting operations were implemented and are still ongoing. The main protective measures were deep grouting curtains and blanket grouting. In addition, to minimize the possibility of dam failure it was recommended to drop the maximum operation water level to ۳۱۹m instead of ۳۳۰m above sea level (a.s.l), because of that at or above this level the rate of subsurface dissolution rises significantly. Many investigations were conducted to evaluate the safety of the dam, and all of them emphasized continued grouting. This paper addresses the details of the various causes behind the continuity of the grouting process and suggests some possible and practical remedial steps that can be carried out to reduce the risk of collapse and keep the dam safe.

کلیدواژه ها:

Mosul Dam ، Seepage ، Karstification ، Grouting