TITLE:
Karstification Effect on the Stability of Mosul Dam and Its Assessment, North Iraq
AUTHORS:
Varoujan K. Sissakian, Nadhir Al-Ansari, Sven Knutsson
KEYWORDS:
Mosul Dam; Karstification; Sink Hole; Iraq
JOURNAL NAME:
Engineering,
Vol.6 No.2,
February
10,
2014
ABSTRACT: Mosul Dam is located on the Tigris river, 50 Km NW of Mosul; it is
113 m in height, 3.4 Km in length, 10 m wide in its crest and has a storage
capacity of 11.1 billion cubic meters. It is an earth fill dam, constructed on
bedrocks of Fat’ha
Formation, which consists of gypsum beds alternated with marl and limestone, in
cyclic nature. The thickness of gypsum beds attains 18 m; they are intensely
karstified even in foundation rocks. Therefore, continuous grouting Programme was planned during
construction, which was completed in June 1984, with planned operation age of
80 years. Due to insufficient grouting in the foundation, during last years of
the last century, the Karstification was enlarged in size and quantity, causing
serious problems to the stability of the dam. Since late eighties of the last
century, the status of the dam and its probable collapse has caused a panic to
the people of Mosul city and near surroundings. Therefore, many attempts were
carried out for assessment of the dam; all of them concluded that the Karstification
is the main problem and recommended continuous grouting, using modern
techniques. In addition, the authorities started to build another “Badush Dam”
south of Mosul Dam so that it can stop the first wave if Mosul Dam if
collapsed. All geophysical and
geological work executed on the dam site; it concluded that the existence of
many weaknesses zones, faults and large karstified areas, in different parts of
the dam site.