ISSN - ISRM

24 ISRM (India) Journal6. CONCLUSIONSThe evaluation of the response of the tunnels usingdiscrete element method indicates that the presence oflining decreases relaxation around the tunnel. Theincrease in the contact force around the tunnel due tothe presence of lining results in arching which leads to amore stable tunnel assembly. The displacementdistribution clearly shows how the unlined tunnelcollapses and the same can be seen from the contactforce and variation of vertical strains. When lining ispresent it increases the confinement of the surroundingsoil and forces it to act as a single mass. Thedisplacement and contact force distributions for a linedtunnel clearly implies a stable configuration for linedtunnels. Also the assembly of twin tunnels is more stablewith less displacement or strains compared to singletunnels and this emphasizes the significance of twintunnels over a single tunnel.REFERENCES1. Potyondy D.O., and Cundall P. A. 2004, A bondedparticlemodel for rock, International Journal of RockMechanics and Mining Sciences 41: 1329-1364.2. Wu B.R., and Lee C.J. 2003, Ground movements andcollapse mechanism induced by tunneling in clayeysoil, IJPMG-Int. J. Physical Model.Geotech. 4: 15-29.3. Choi Y.K., Park, J.H., Kwon O.Y. and Woo S.B. 2005,Longitudinal arching characteristics around face of asoil tunnel with crown and face-reinforcement –laboratory investigation, Proceedings of the 31st ITA-AITES World Tunnel Congress. 917-923.4. Rowe R.K. and Kack G.J. 1983, A theoreticalexamination of the settlements induced by tunnelingfour case histories, Canadian Geotechnical Journal20:299-314.5. Lee K.M. and Rowe R.K. 1991, An analysis of threedimensionalground movements: the Thunder Baytunnel, Canadian Geotechnical Journal 28: 25-41.6. Funatsu T. Hosino T., Sawae H., and Shimizu N.2008, Numerical analysis to better understand themechanism of the effects of ground supports andreinforcements on the stability of tunnels using thedistinct element method Tunneling and UndergroundSpace Technology 23: 561-573.7. Tannant D.D. and Wang C. 2004, Thin tunnel linersmodelled with particle flow code EngineeringComputation: Int. J. for Computer-Aided Engineering21(2-4): 318 – 342.8. Kasper T. and Meschke G. 2004, A 3D finite elementsimulation model for TBM tunnelling in soft groundInternational Journal for Numerical and AnalyticalMethods in Geomechanics 28: 1441–1460.9. Cundall P. A. 1971, A Computer Model for SimulatingProgressive Large-Scale Movements in Blocky RockMechanics, Proc.Symp.Intl. Soc. Rock Mecha. Nancy,France,2: 129-136.10. Itasca Consulting Group Inc. PFC 3D (Particle Flowcode in 3 Dimensions), Version 4.0 Minneapolis, 200811. ISRM, 1983, Suggested methods for determining thestrength of rock materials in triaxial compression:revised version. International Journal of RockMechanics & Mining Sciences Geomech Abstr.20:291-295.FORTHCOMING ACTIVITIES OF INDIAN NATIONALGROUP OF ISRMSeminar on "Geotechnical Challenges in Water Resources Projects", 19-20 January 2012, DehradunExecution of multipurpose water resources projects located in complicated geological settings is a challenge to engineers.Despite tremendous all round advancement in technologies, there is still scope to learn and know more about thegeotechnical challenges faced during excavations and its implications on design as well as execution. Both design andconstruction engineers would always be keen to know what advancements are taking place in their respective fields toface such challenges and utilize the knowledge for most economical and safe design for construction of a project.These projects require application of modern principles of rock mechanics, which warrants deliberations and collaborationto facilitate flow of appropriate technology to enable successful implementation of such projects under a time-boundprogramme in a cost-effective manner, conforming to environmental requirements.Safety during tunnel and underground construction is of paramount importance not only to the stability of structures butalso to ensure safety of the work force. Safety in tunnels and cavities may be endangered due to sudden rock falls,geological failures, collapse of underground opening or a part of opening, etc.The objective of the proposed Seminar, being organized by the Indian National Group of International Society for Rock Mechanicsand the Central Board of Irrigation & Power and, is to provide a forum for the design and construction engineers to discuss thesolutions to various geological and geotechnical surprises encountered during the execution of various River Valley Projectsand use the knowledge for safe and economical design and construction of such projects.Volume 1 v No. 1 v January 2012