Effect of Model Dimension in Numerical Simulation on Assessment of Water Inflow to Tunnel in Discontinues Rock

Authors: Hadi Farhadian, Homayoon Katibeh

Abstract:

Groundwater inflow to the tunnels is one of the most important problems in tunneling operation. The objective of this study is the investigation of model dimension effects on tunnel inflow assessment in discontinuous rock masses using numerical modeling. In the numerical simulation, the model dimension has an important role in prediction of water inflow rate. When the model dimension is very small, due to low distance to the tunnel border, the model boundary conditions affect the estimated amount of groundwater flow into the tunnel and results show a very high inflow to tunnel. Hence, in this study, the two-dimensional universal distinct element code (UDEC) used and the impact of different model parameters, such as tunnel radius, joint spacing, horizontal and vertical model domain extent has been evaluated. Results show that the model domain extent is a function of the most significant parameters, which are tunnel radius and joint spacing.

Keywords: Water inflow, Tunnel, Discontinues rock, Numerical simulation.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1100450

References:

[1] H. Farhadian, A. Aalianvari, H. Katibeh, “Optimization of Analytical Equations of Groundwater Seepage into Tunnels: A Case Study of Amirkabir Tunnel,” Journal geological society of India, 80 (1): 96-100, 2012. doi: 0016-7622/2012-80-1-96/$
[2] H. Farhadian, H. Katibeh, A.R. Sayadi, “Prediction of Site Groundwater Rating (SGR) for Amirkabir Tunnel Using Artificial Neural Networks,” International Journal of Mining, Metallurgy & Mechanical Engineering (IJMMME) 1(1), 2013.
[3] M. El Tani, “Circular tunnel in a semi-infinite aquifer,” Tunn Undergr Space Technol 18(1):49–55, 2003. doi:10.1016/S0886-7798(02)00102-5
[4] P. Perrochet, “Confined flow into a tunnel during progressive drilling: An analytical solution,” Ground Water 43(6):943–946, 2005. doi: 10.1111/j.1745-6584.2005.00108.x
[5] D. Kolymbas and P. Wagner, “Groundwater ingress to tunnels – the exact analytical solution,” Tunn Undergr Space Technol 22(1):23–27, 2007. doi:10.1016/j.tust.2006.02.001
[6] P. Gattinoni, L. Scesi and S. Terrana, “Hydrogeological risk analysis for tunneling in anisotropic rock masses,” In: Proceedings of the ITAAITES World Tunnel Congress “Underground Facilities for Better Environment & Safety”, Arga, India, pp. 1736–174, 2008.
[7] J. Molinero, J. Samper and R. Juanes, “Numerical modeling of the transient hydrogeological response produced by tunnel construction in fractured bedrocks,” Eng Geol 64(4):369–386, 2002. doi:10.1016/S0013-7952(01)00099-0
[8] J.H. Hwang, and C.C. Lu, “A semi-analytical method for analyzing the tunnel water inflow,” Tunn Undergr Space Technol 22(1):39– 46, 2007. doi:10.1016/j.tust.2006.03.003
[9] C. Zangerl, E. Eberhardt, K.F. Evans and S. Loew, “Consolidation settlements above deep tunnels in fractured crystalline rock: part 2, numerical analysis of the Gotthard highway tunnel case study,” Int J Rock Mech Min Sci 45(8):1211–1225, 2008.
[10] P. Gattinoni and L. Scesi, “An empirical equation for tunnel inflow assessment: application to sedimentary rock masses,” Hydrogeology J 18(8):1797–1810, 2010. doi: 10.1007/s10040-010-0674-1
[11] K. Esmaieli, J. Hadjigeorgiou and M. Grenon, “Estimating geometrical and mechanical REV based on synthetic rock mass models at Brunswick Mine,” Int J Rock Mech Min Sci 47(6):915–926, 2010. doi:10.1016/j.ijrmms.2010.05.010
[12] B. Indraratna and P. Ranjith, “Effects of boundary conditions and boundary block size on inflow to an underground excavation – sensivity analysis,” IMWA Proceedings, 1998.
[13] D. Cesano, A.C. Bagtzoglou and B. Olofsson, “Quantifying fractured rock hydraulic heterogeneity and groundwater inflow prediction in underground excavations: the heterogeneity index,” Tunn Undergr Space Technol 18(1):19 –34, 2003.
[14] J. Moon and G. Fernandez, “Effect of Excavation-Induced Groundwater Level Drawdown on Tunnel Inflow in a Jointed Rock Mass,” Eng Geol 110(3-4):33–42, 2010. doi:10.1016/j.enggeo.2009.09.002
[15] J. Moon and S. Jeong, “Effect of highly pervious geological features on ground water flow into a tunnel,” Eng Geol 117(3-4):207–216, 2011. doi:10.1016/j.enggeo.2010.10.019
[16] C. Butscher, “Steady-state groundwater inflow into a circular tunnel,” Tunn Undergr Space Technol 32:158–167, 2012. doi:10.1016/j.tust.2012.06.007
[17] H. Farhadian, H. Katibeh, “Groundwater Seepage Estimation into Amirkabir Tunnel Using Analytical Methods and DEM and SGR Method,” World Academy of Science, Engineering and Technology, International Journal of Civil, Structural, Construction and Architectural Engineering 9(3), 2015.