Document Type : Original Research Paper

Authors

1 Faculty of Land Resources Engineering, Kunming University of Science and Technology, Yunnan, China

2 Department of Mining Engineering Karakoram International University (KIU), Gilgit, Pakistan

Abstract

The study examined the influence of cohesion, friction angle, and tunnel diameter on stability within engineering and geotechnical frameworks, while considering the consequences of nearby excavations on the overall stability assessment. The results show that a higher angle of internal friction leads to a decrease in soil stability number and weighting coefficient. Tunnel diameter significantly affects face support pressure, with larger diameters requiring stronger support due to increased stress. Higher friction angles help stabilize tunnel faces and mitigate diameter-related pressure effects. Stress redistribution around the tunnel is significant within 2 meters from the center, transitioning to elastic behavior elsewhere. A safety factor of 1.3 ensures tensile failure prevention in single and twin tunnels. Balanced stress distribution between tunnels with a slight difference is observed under isotropic in-situ stress. Numerical modeling enhances stress estimations and reveals changes during tunnel excavation, weakening the rock mass. Ground reaction curve analysis with support measures shows reduced tunnel convergence after implementation, suggesting support strategies like extended bolts using updated rock mass rating. The study improves tunnel design and stability assessment by comprehensively understanding stress redistribution and support strategies.

Keywords

Main Subjects

[1]. Fu, J., Safaei, M.R., Haeri, H., et al. (2022) Experimental Investigation on Deformation Behavior of Circular Underground Opening in Hard Soil using a 3D Physical Model. Journal of Mining and Environment, 13(3), 727-749.
[2]. Rezaei, A.S., Sarfarzi, V., Babanouri,N., Omidimanesh,M., Jahanmiri, S., (2023). Failure Mechanism of Rock Pillar Containing Two Edge Notches: Experimental Test and Numerical Simulation.
[3]. Wan, M., Standing, J.R., Potts, D.M., Burland, J.B., (2017). Measured short-term ground surface response to EPBM tunnelling in London Clay. Géotechnique, 67(5), 420-445.
[4]. Luciani, A., and Peila, D., (2019). Tunnel Waterproofing: Available Technologies and Evaluation Through Risk Analysis. International Journal of Civil Engineering, 17(1), 45-59.
[5]. Wang, X., Jinxinget, L., He, S., Garnes, R.S., Zhang, Y., (2020). Karst geology and mitigation measures for hazards during metro system construction in Wuhan, China. Natural Hazards, 103(3), 2905-2927.
[6]. Gong, C., Ding, W.,  Xie, D., (2020). Twin EPB tunneling-induced deformation and assessment of a historical masonry building on Shanghai soft clay. Tunnelling and Underground Space Technology, 98, 103300.
[7]. Sarfarazi, V.,  (2020). Behavior of Tunnel and Neighboring Joint with and without Presence of Rock Bolt under biaxial loads; Particle Flow Code Approach. Journal of Mining and Environment, 11(3), 855-864.
[8]. Doležalová, M.,(2001). Tunnel complex unloaded by a deep excavation. Computers and Geotechnics, 28(6-7), 469-493.
[9]. Sharma, J., Hefny, A.M.,Zhao, J., Chan, C.W., (2001). Effect of large excavation on deformation of adjacent MRT tunnels. Tunnelling and Underground Space Technology, 16(2) 93-98.
[10]. Hu, Z., ( 2003). Design and construction of a deep excavation in soft soils adjacent to the Shanghai Metro tunnels. Canadian Geotechnical Journal, 40(5), 933-948.
[11]. Doležalová, M., (2001). Tunnel complex unloaded by a deep excavation. Computers and Geotechnics, 28(6), 469-493.
[12]. Sharma, J.S., (2001). Effect of large excavation on deformation of adjacent MRT tunnels. Tunnelling and Underground Space Technology, 16(2), 93-98.
[13]. Wang, W., Xu., Z. and Li., Q., (2018) Design and Construction of Deep Excavations in Shanghai. Geotechnical Research, 5, 1-55.
[14]. Sarfarazi, V., Asgari, K., Abad, S.M.B., (2021).  Interaction between tunnel and surface foundation using PFC2D. Journal of Mining and Environment, 12(3), 785-798
[15]. Zhang, J.F., and Chen, J.J., (2013). Prediction of tunnel displacement induced by adjacent excavation in soft soil. Tunnelling and Underground Space Technology, 36, 24-33.
[16]. Athar, M.F., Zaid, M., Sadique, R., (2019). Stability of Different shapes of Tunnels in Weathering Stages of Basalt.
[17]. Luc Leroy, M., Ndop, J., Ndjaka, J., (2015). Numerical investigations of stresses and strains redistribution around the tunnel: Influence of transverse isotropic behavior of granitic rock, in situ stress and shape of tunnel. Journal of Mining Science, 51, 497-505.
[18]. Fama, M.E.D., 3 - Numerical Modeling of Yield Zones in Weak Rock, in Analysis and Design Methods, C. Fairhurst, Editor. 1993, Pergamon: Oxford. p. 49-75.
[19]. Kirsch, A.,(2010). Experimental investigation of the face stability of shallow tunnels in sand. Acta Geotechnica, 5, 43-62.
[20]. Hou, C., Zhong, J., Yang, X., (2023). Three-dimensional stability assessments of a non-circular tunnel face reinforced by bolts under seepage flow conditions. Tunnelling and Underground Space Technology, 131, 104831.
[21]. Ninić, J., (2020). Integrated parametric multi-level information and numerical modelling of mechanised tunnelling projects. Advanced Engineering Informatics, 43, 101011.
[22]. Guan, K., (2018). A finite strain numerical procedure for a circular tunnel in strain-softening rock mass with large deformation. International Journal of Rock Mechanics and Mining Sciences, 112, 266-280.
[23]. Hoek, E., Diederichs, M.S.,(2006). Empirical estimation of rock mass modulus. International Journal of Rock Mechanics and Mining Sciences, 43(2), 203-215.
[24]. Shiau, J., Al-Asadi, F.,(2020). Three-dimensional heading stability of twin circular tunnels. Geotechnical and Geological Engineering, 38, 2973-2988.
[25]. Islam, M.S., Iskander, M.,(2023). Three-dimensional numerical investigation of ground settlement caused by piggyback twin tunnels. Tunnelling and Underground Space Technology, 134, 104970.
[26]. Najm, S.J., Daraei, A.,(2023). Forecasting and controlling two main failure mechanisms in the Middle East’s longest highway tunnel. Engineering Failure Analysis, 146, 107091.
[27]. Chehade, F.H., Shahrour, I.,(2008). Numerical analysis of the interaction between twin-tunnels: Influence of the relative position and construction procedure. Tunnelling and underground space technology, 23(2), 210-214.
[28]. Liu, Z., et al., (2021). A simplified two-stage method to estimate the settlement and bending moment of upper tunnel considering the interaction of undercrossing twin tunnels. Transportation Geotechnics, 29, 100558.
[29]. Zheng, G., et al., (2023). Relating twin-tunnelling-induced settlement to changes in the stiffness of soil. Acta Geotechnica, 18(1), 469-482.
[30]. Abbas, N., et al.,(2022).  Correlation of Schmidt Hammer Rebound Number and Point Load Index with Compressive Strength of Sedimentary, Igneous and Metamorphic Rocks. Journal of Mining Science, 58(6), 903-910.
[31]. Zeng, G., Wang, H. Jiang, M.,(2023).  Analytical stress and displacement of twin noncircular tunnels in elastic semi-infinite ground. Computers and Geotechnics,160, 105520.
[32]. Shah, k.S., et al., (2023). Analysis of Granite Failure Modes and Energy Conversion Under Uniaxial Compression at Various Temperatures. Journal of Mining and Environment, 14(2), 493-506.
[33]. Bobet, A., (2010). Numerical methods in geomechanics. The Arabian Journal for Science and Engineering,  35.
[34]. Barpi, F., and Peila,  D., (2012). Influence of the tunnel shape on shotcrete lining stresses. Computer‐Aided Civil and Infrastructure Engineering, 27(4),  260-275.
[35]. Alagha, A.S.N., and Chapman, D.N., (2019). Numerical modelling of tunnel face stability in homogeneous and layered soft ground. Tunnelling and Underground Space Technology, 94, 103096.
[36]. Ye, Z., et al., (2023). A digital twin approach for tunnel construction safety early warning and management. Computers in Industry, 144, 103783.
[37]. Zhang, H., et al., (2023). Stability evaluation of rock pillar between twin tunnels using the YAI. Scientific Reports, 13(1), 13187.
[38]. Islam, M.S., and Iskander, M., (2021). Twin tunnelling induced ground settlements: A review. Tunnelling and Underground Space Technology, 110, 103614.
[39]. Leca, E., and Dormieux, L., (1990). Upper and lower bound solutions for the face stability of shallow circular tunnels in frictional material. Géotechnique, 40(4), 581-606.
[40]. Liu, K., et al., (2021). Tunnel face stability in soils – Influence of the soil arching effect. International Journal of Geomechanics, 21.
[41]. Ads, A., Shariful Islam, M., Iskander, M., (2021). Effect of Face Losses and Cover-to-Diameter Ratio on Tunneling Induced Settlements in Soft Clay, Using Transparent Soil Models. Geotechnical and Geological Engineering,  39(8), 5529-5547.
[42]. Minh, N.V., (2016). Reducing the cover-to-diameter ratio for shallow tunnels in soft soils.
[43]. Lai, F., et al., (2021). Ground movements induced by installation of twin large diameter deeply-buried caissons: 3D numerical modeling. Acta Geotechnica, 16, 2933-2961.
[44]. Chortis, F., and Kavvadas, M., (2021). Three-dimensional numerical investigation of the interaction between twin tunnels. Geotechnical and Geological Engineering, 39(8), 5559-5585.
[45]. Abbas, N., et al., (2023). Empirical Evaluation of RMR, GSI, and Q for Underground Excavations. Iranian Journal of Science and Technology, Transactions of Civil Engineering.
[46]. Bahri, M., et al., (2022). Numerical Model Validation for Detection of Surface Displacements over Twin Tunnels from Metro Line 1 in the Historical Area of Seville (Spain). Symmetry, 14(6), 1263.