Masjed-Soleiman hydroelectric power station is one of the most recent achievements in underground construction in Iran. This paper will review the general geology, geotechnics, excavation, support system and monitoring results of the caverns. Based on the results of monitoring and computer modelling, several suggestions for improvement of the future extension program will be discussed.


La centrale hydroelectrique de Masjed-Soleiman est un des plus recents aceoplissements dans la construction souterraine en Iran. La geologie generale et la geotechnique des cavernes, leur excavation, systeme de soutenement et les resultats de manipulation dans les caverne sont discutes. Base sur les resultats de la manipulation et sur le resultats de la modelisation avec l' ordinateur, plusieurs suggestions sont presentees pour ameliorer l' execution du programme d' extension de cette centrale.


Die Masjed soleiman Wasserkraftanlage ist eine recente Ausfuehrung der untertaegigen Bauten im Iran. Die allgemeine Geologie, die Daton der Geotechnik der Kaverne. deren ausbrechen, sowie Ausbausystem und schliesslich dieErgebnisse sind cliskutiert. Auf Grund der Ergebnisse wurde ein Computermodell hergestellt und Vorschlage zur Erweiterung des Programms gemacht.


In the last ten years several dams with underground power stations have been under construction in Iran. Masjed-Soleiman dam and power Station is one of these projects, located at north east of the Masjed-Soleiman city.

The dam is rock fill type, 480m long, 177m high, creating a 230 million m3 reservoir. Its underground power station, in the right bank, and at the depth of 250m, includes a l54.5m x30mx43m powerhouse cavern and a 110mx13.6mx21m cavern for installation of transformers. It also includes four 250MW generator units. Another set of similar units is to be installed in the extension phase. The caverns were excavated in 1995–97. This paper describes the geotechnical conditions, the excavation method, support systems, and results of monitoring of the caverns, offering a few suggestions regarding the future extension works.


Preliminary investigations including geological mapping of the dam site, drilling boreholes, and rock mechanic tests were performed before 1990 (Moshanir & Lahmeyer Int. 1990), Major explorations, commenced in summer 1990, were: a) Excavation of 6 trenches, 77 test pits and 31 auger boreholes. b) Excavation of an exploratory drift in the right bank, 550m long, to reach the caverns position. c) Drilling a number of boreholes in different location, including the exploratory drift to obtain core samples. d) A series of laboratory tests on the samples such as uniaxial and triaxial compressive tests, Brazilian tests, point load index, and determination of RQD. e) A few dilatometre, over coring and fiat jack tests. 1) Performing about 290 Lugeon and Lefrance tests. g) Engineering classification of rock mass using RMR and Q systems (Moshanir & Lahmeyer Int. 1993).

The investigations were continued during excavation process. When the cavern walls were exposed and could be sampled, some laboratory tests and rock classification were particularly repeated. Table 1 shows the summary of parameters for the main rock types (Moshanir & Lahmeyer Int. 1993).

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