Bakhtiari dam is located on the Bakhtiari river, 120？km away from the north of the Andimeshk city. Upper diversion tunnel of this dam with large cross section (13.7？m excavation diameter) and more than 1？km length is a huge construction. The tunnel is placed in the Sarvak formation carbonate rocks of Bangestan group which passes through seven different geological zones with various specifications (SV1, SV2, SV3, SV4, SV5, SV6, and SV7). Joint studies show two main discontinuit including bedding and a main group of joint (J1) together with random joints (faults and fractures). Most of discontinuities have been filled mainly by calcite or calcite and clay. Data deduced from testing and analysis shows good-to-excellent RQD classes with 75 to 90 values. Based on RMR and Q methods, generally rock masses have good to very good quality with 61 to 95 values for RMR and 10 to 35 values for Q. Based on conducted stability analysis, suitable supports were suggested for tunnel by RMR and Q methods. As a result, it can be concluded that all units have a good stability. Therefore, systematic rock bolting with 40–50？mm unreinforced shotcrete has been proposed for some special place. For rock support, according to RMR method, 3？m rock bolts in crown, 2.5？m spacing and with 50？mm shotcrete in crown has been proposed also 3？m rock bolts, based on Q method, 2.3-2.4？m spacing with systematic Bolting without shotcrete or 40？mm unreinforced shotcrete in some units, has been proposed. According to RMR method, for SV5 zone with very good and excellent quality, local 33 bolting without shotcrete and 3m rock bolts, 3？m spacing and spot bolting according to Q method has been proposed. 1. Introduction In recent years, following the increasing need to create spaces underground with larger scale and in greater depth in poor areas (such as underwater), identifying more and more of the earth is evident. In relation to construction of dams, geological survey is the most important parts of studies which can be useful and valuable information about the design of underground spaces offer [2]. Feasibility of these constructions in natural materials, such as rock and soil, causes the geological conditions to play a major role in their stability [3]. Dams are considered as one of the most important civil structures. Arch dams with high stresses on their foundation highlight the role of rock mechanics studies. It should be noted that many geological data cannot be directly applied in the design of underground constructions, so in recent years; many efforts have been made for geotechnical
References
[1]
N. Barton, R. Lien, and J. Lunde, “Engineering classification of rock masses for the design of tunnel support,” Rock Mechanics Felsmechanik Mécanique des Roches, vol. 6, no. 4, pp. 189–236, 1974.
[2]
E. Hoek, “Rock Enginnering,” Course Notes, 2007.
[3]
E. Hoek and P. Marinos, “Predicting tunnel squeezing problem in weak heterogeneous rock masses,” Tunnels and Tunnelling international, Part1, November 2000, Part2, December 2000.
[4]
B. Singh and R. K. Geol, Tunnelling in Weak Rock, vol. 5 of Elsevier Geo-Engineering Book Series, 2006.
[5]
Z. T. Bieniawski, Engineering Rock Mass Classifications, John Wiley and Sons, New York, NY, USA, 1989.
[6]
T. Miranda, A. Gomes Correia, I. Nogueira, M. Santos, P. Cortez, and L. Ribeiro e Sousa, “Alternative models for the calculation of the RMR and Q indexes for granite rock masses,” in Proceedings of the 5th International Workshop on Application of Computational Methods in Geotechnical Engineering, R. Sousa, M. M. Fernandes, E. Vargas Jr., and R. Azevedo, Eds., pp. 151–162, Taylor & Francis Group, Guimar？es, Portugal, April 2007.
[7]
B. Sing and R. k. Goel, Rock Mass Classification, University of Roorke India, 1999.
[8]
K. Rajnish and S. G. Bhawani, Tunneling in Weak Rocks, Elsevier Geo-Engineering Book Series, 2006.
[9]
S. M. Hossaini, F. Nezhadshahmohamad, and M. Dadkhah, “Stability assessment and support design for water deviation binary tunnels of bakhtiyari dam-Iran,” in Proceedings of the 11th Underground Coal Operators' Conference, University of Wollongong Research Online, 2011.
[10]
E. Grimstad and N. Barton, “Updating the Q-System for NMT,” in Proceedings of the International Symposium on Sprayed Concrete—Modern Use of Wet Mix Sprayed Concrete for Underground Support, Fagernes, pp. 46–66, Norwegian Concrete Association, Oslo, Norway, 1993.
[11]
Iran Water and Power Resourced Development Co, “Geological report of bakhtiari dam,” 2006.
[12]
K. R. Davis, “The geology of an area in southest Lurestan, GR1104,” 1964.
[13]
Iran Water and Power Resourced Development Co, “In-situ and laboratory rock mechanics tests of Bakhtiari Dam,” 2008.
[14]
Anon, “Classification of rocks and soils for engineering geological mapping,” Bulletin of the International Association of Engineering Geology, no. 19, pp. 364–371, 1979.
[15]
N. R. Barton, “Predicting the behavior of underground opening in rock,” Manuel Rocha Memorial Lecture, Lisbon, Norwegian Geotechnical Institute, Oslo, Norway, 1978.
[16]
D. Saiang, “Stability analysis of the blast-induced damage zone by continuum and coupled continuum-discontinuum methods,” Engineering Geology, vol. 116, no. 1-2, pp. 1–11, 2010.
[17]
N. Barton, “Some new Q-value correlations to assist in site characterisation and tunnel design,” International Journal of Rock Mechanics and Mining Sciences, vol. 39, no. 2, pp. 185–216, 2002.
[18]
T. Ramamurthy, “A geo-engineering classification for rocks and rock masses,” International Journal of Rock Mechanics and Mining Sciences, vol. 41, no. 1, pp. 89–101, 2004.
[19]
E. Hoek and M. S. Diederichs, “Empirical estimation of rock mass modulus,” International Journal of Rock Mechanics and Mining Sciences, vol. 43, no. 2, pp. 203–215, 2006.
[20]
Z. Gurocak, P. Solanki, and M. M. Zaman, “Empirical and numerical analyses of support requirements for a diversion tunnel at the Boztepe dam site, eastern Turkey,” Engineering Geology, vol. 91, no. 2–4, pp. 194–208, 2007.
[21]
H. Stille and A. Palmstr？m, “Classification as a tool in rock engineering,” Tunnelling and Underground Space Technology, vol. 18, no. 4, pp. 331–345, 2003.
[22]
A. Palmstr？m and R. Singh, “The deformation modulus of rock masses—comparisons between in situ tests and indirect estimates,” Tunnelling and Underground Space Technology, vol. 16, no. 2, pp. 115–131, 2001.
[23]
A. Palmstr？m, “Characterizing rock masses by the RMi for Use in Practical Rock Engineering: Part 1: The development of the Rock Mass index (RMi),” Tunnelling and Underground Space Technology, vol. 11, no. 2, pp. 175–188, 1996.
[24]
A. Palmstrom, RMI-A rock mass classification system for rock engineering purposes [Ph.D. thesis], University of Oslo, 1995.
[25]
A. Palmstorm, “The volumetric joint count- a useful and simple neasure of the degree of rock jointing,” in Proceedings of the 4th Congress of the International Association of Engineering Geology, vol. 5, pp. 221–228, New Delhi, India, 1985.
[26]
H. Katibeh and A. Aalianvari, “Development of a new method for tunnel site rating from groundwater hazard point of view,” Journal of Applied Sciences, vol. 9, no. 8, pp. 1496–1502, 2009.
[27]
Z. T. Bieniawski, Rock Mechanics Design in Mining and Tunneling, A. A. Balkema publishing Co, 1984.
[28]
A. Palmstrom, “Combining the RMR, Q, and RMi classification systems,” 25p, 1996, http://www.rockmass.net/.
