Squeezing rock conditions at phyllite-slate zone in Golab water conveyance tunnel, Iran: A case study

Abstract

Squeezing ground in tunneling is associated with large deformation of the tunnel face. In this study, squeezing characteristics of the ground and rock conditions in Golab water conveyance tunnel, Iran, are discussed and the classification of squeezing behavior around zones where the problems occurred is presented. The squeezing conditions were investigated using empirical and semi empirical methods. In the next step, creep convergence of the tunnel with Burger’s model was simulated by the numerical method. Numerical analysis showed that wall displacement (64.1 mm) of the Golab tunnel was more than allowable strain (1% of the tunnel diameter), therefore, it was found that squeezing phenomenon could exist, leading to the failure of the support system. Numerical analysis at the phyllite-slate zone also showed squeezing conditions due to the weakness of rock mass and high overburden that this situation cause failure in the segmental lining. In this research, failure in segmental lining in phyllite-slate zone verified the results of the numerical modeling.

Keywords

squeezing / large deformation / Burger’s model / numerical analysis / failure / segmental lining

References

[1] BasnetC BEvaluation on the squeezing phenomenon at the headrace tunnel of Chameliya hydroelectric project, Nepal [D], 2013, Trondheim, Norwegian University of Science and Technology

[2] RamoniM, AnagnostouG. The interaction between shield, ground and tunnel support in TBM tunneling through squeezing ground [J]. Rock Mechanics and Rock Engineering, 2011, 44(1): 37-61

[3] SinghM, SinghB, ChoudhariJ. Critical strain and squeezing of rock mass in tunnels [J]. Tunneling and Underground Space Technology, 2007, 22(3): 343-350

[4] ScusselD, ChandraS. New approach to the design of tunnels in squeezing ground [J]. International Journal of Geomechanics, 2014, 14(1): 110-117

[5] BarlaG. Squeezing rocks in tunnels [J]. ISRM News Journal, 1995, 2(34): 44-49

[6] DalgicS. Tunneling in squeezing rock, the Bolu tunnel, Anatolian Motorway, Turkey [J]. Engineering Geology, 2002, 67(12): 73-96

[7] TerzaghiKProctorR V, WhiteT L. Rock defects and loads on tunnel supports [M]//. Rock Tunneling with Steel Supports, 19461599

[8] SinghB, JethwaJ L, DubeA K, SinghB. Correlation between observed support pressure and rock mass quality [J]. Tunneling and Underground Space Technology, 1992, 7(1): 59-74

[9] DubeA KSqueezing under high stress conditions, assessment and prevention of failure phenomena in rock engineering [M], 1993

[10] AydanO, AkagiT, KawamotoT. The squeezing potential of rocks around tunnels: Theory and prediction [J]. Rock Mechanics and Rock Engineering, 1993, 26(2): 137-163

[11] AydanO, AkagiT, KawamotoT. The squeezing potential of rocks around tunnels: Theory and prediction with examples taken from Japan [J]. Rock Mechanics and Rock Engineering, 1996, 29(3): 125-143

[12] SchubertW, SchubertP. Tunnels in squeezing rock: failure phenomena and counteractions [C]//. International Symposium on Assessment and Prevention of Failure Phenomena in Rock Engineering, 1993479484

[13] BartonN, GrimstadE. The Q-system following twenty years of application in NMT support selection [C]// 43rd Geomechanic Colloquy. Salzburg, Felsbau, 1994, 12(6): 428-436

[14] GoelR K, JethwaJ L, PaithankarA G. Tunneling through the young Himalayas–A case history of the Maneri-Uttarkashi power tunnel [J]. Engineering Geology, 1995, 39(12): 31-44

[15] HoekE. Big tunnels in bad rock [J]. The ASCE Journal of Geotechnical and Geoenvironmental Engineering, 2001, 127(9): 726-740

[16] VermaA K, SinghT N. Assessment of tunnel instability—A numerical approach [J]. Arabian Journal of Geosciences, 2010, 3(2): 181-192

[17] RamoniM, AnagnostouG. Tunnel boring machines under squeezing conditions [J]. Tunneling and Underground Space Technology, 2010, 25(2): 139-157

[18] RamoniM, AnagnostouG. Thrust force requirements for TBMs in squeezing ground [J]. Tunneling and Underground Space Technology, 2010, 25(4): 433-455

[19] RamoniM, AnagnostouG. The interaction between shield ground and tunnel support in TBM tunneling through squeezing ground [J]. Rock Mechanics and Rock Engineering, 2011, 44(1): 37-61

[20] RamoniM, AnagnostouG. The effect of consolidation on TBM shield loading in water-bearing squeezing ground [J]. Rock Mechanics and Rock Engineering, 2011, 44(1): 63-83

[21] BarlaG, PelizzaSTBM tunneling in difficult ground conditions [M], 2000

[22] GoodmanR EIntroduction to rock mechanics [M], 1989

[23] ISRM.. Methods for the quantitative description of rock masses and discontinuities [J]. International Journal of Rock Mechanics and Mining Sciences, 1978, 15: 319-368

[24] HoekE, MarinosP. Predicting tunnel squeezing problems in weak, heterogeneous rock masses, Part 1 [J]. Tunnels and Tunneling International, 2000, 32(11): 45-51

[25] HoekE, MarinosP. Predicting tunnel squeezing problems in weak heterogeneous rock masses, Part 2 [J]. Tunnels and Tunneling International, 2000, 33(12): 33-36

[26] Itasca consulting group. User manual for Flac3D [R]. Version 4. Minnesota, 2009.

[27] HoekE, BrownE TUnderground excavations in rock [M], 1980, London, Institution of Mining and Metallurgy

[28] SinghB, GoelR KRock mass classification: a practical approach in civil engineering [M], 1999

[29] StephanssonO. Rock stress measurement by sleeve fracturing [C]//. 5th International Congress Rock Mechanics, 1983129137

[30] SheoreyP R. A theory for in-situ stresses in isotropic and transversely isotropic rock [J]. International Journal of Rock Mechanics and Mining Sciences, 1994, 31(1): 23-34

[31] SheoreyP R, MohanG M, SinhaA. Influence of elastic constants on the horizontal in situ stress [J]. International Journal of Rock Mechanics and Mining Sciences, 2001, 38(8): 1211-1216