Support design method for deep soft-rock tunnels in non-hydrostatic high in-situ stress field

Abstract

Due to the long-term plate tectonic movements in southwestern China, the in-situ stress field in deep formations is complex. When passing through deep soft-rock mass under non-hydrostatic high in-situ stress field, tunnels will suffer serious asymmetric deformation. There is no available support design method for tunnels under such a situation in existing studies to clarify the support time and support stiffness. This study first analyzed the mechanical behavior of tunnels in non-hydrostatic in-situ stress field and derived the theoretical equations of the ground squeezing curve (GSC) and ground loosening curve (GLC). Then, based on the convergence confinement theory, the support design method of deep soft-rock tunnels under non-hydrostatic high in-situ stress field was established considering both squeezing and loosening pressures. In addition, this method can provide the clear support time and support stiffness of the second layer of initial support. The proposed design method was applied to the Wanhe tunnel of the China-Laos railway in China. Monitoring data indicated that the optimal support scheme had a good effect on controlling the tunnel deformation in non-hydrostatic high in-situ stress field. Field applications showed that the secondary lining could be constructed properly.

Keywords

non-hydrostatic stress field / high in-situ stress / deep soft-rock tunnel / squeezing pressure / loosening pressure / support design method

References

[1] WangY-q, LiJ-q, WangZ-f, et al. . Structural failures and geohazards caused by mountain tunnel construction in fault zone and its treatment measures: A case study in Shaanxi. Engineering Failure Analysis, 2022, 138: 106386 J]

[2] QiaoY-f, TangJ, LiuG-z, et al. . Longitudinal mechanical response of tunnels under active normal faulting. Underground Space, 2022, 7(4): 662-679 J]

[3] ChenS-j, FengF, WangY-j, et al. . Tunnel failure in hard rock with multiple weak planes due to excavation unloading of in situ stress. Journal of Central South University, 2020, 27(10): 2864-2882 J]

[4] SiX-f, HuangL-q, GongF-q, et al. . Experimental investigation on influence of loading rate on rockburst in deep circular tunnel under true-triaxial stress condition. Journal of Central South University, 2020, 27(10): 2914-2929 J]

[5] ChenZ-q, HeC, XuG-w, et al. . A case study on the asymmetric deformation characteristics and mechanical behavior of deep-buried tunnel in phyllite. Rock Mechanics and Rock Engineering, 2019, 52(11): 4527-4545 J]

[6] LiH-b, YangX-g, ZhangX-b, et al. . Deformation and failure analyses of large underground caverns during construction of the Houziyan Hydropower Station, Southwest China. Engineering Failure Analysis, 2017, 80164-185 J]

[7] YangJ-p, ChenW-z, ZhaoW-s, et al. . Geohazards of tunnel excavation in interbedded layers under high in situ stress. Engineering Geology, 2017, 230: 11-22 J]

[8] WuD, ChenZ-q, GanL-w, et al. . Study of force mechanism of asymmetrical deformation of deep-buried layered surrounding rock tunnel under high ground stress. Tunnel Construction, 2018, 38(11): 1813-1821[J]

[9] ZhangY-h, LuY-r, ZhouH-m, et al. . Study on the relationship between failure characteristics of surrounding rock and in situ stress direction. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(S2): 3526-3535[J]

[10] ZhengK-y, ShiC-h, ZhaoQ-j, et al. . Failure mechanisms and dynamic process control measures of deep buried tunnels in tectonic fracture zones under high in-situ stresses-a case study in Southwestern China. Frontiers in Earth Science, 2023, 11: 1289251 J]

[11] ZhengK-y, ShiC-h, ZhaoQ-j, et al. . A computational method for tunnel energy evolution in strain-softening rock mass during excavation unloading based on triaxial stress paths. Computers and Geotechnics, 2024, 169106212 J]

[12] AziziF, KoopialipoorM, KhoshrouH. Estimation of rock mass squeezing potential in tunnel route (case study: Kerman water conveyance tunnel). Geotechnical and Geological Engineering, 2019, 37(3): 1671-1685 J]

[13] ChenJ-h, LiuL, ZengB-q, et al. . A constitutive model to reveal the anchorage mechanism of fully bonded bolts. Rock Mechanics and Rock Engineering, 2023, 56(3): 1739-1757 J]

[14] AroraK, GutierrezM, HedayatA, et al. . Tunnels in squeezing clay-rich rocks. Underground Space, 2021, 6(4): 432-445 J]

[15] CaoC-y, ShiC-h, LeiM-f, et al. . Squeezing failure of tunnels: A case study. Tunnelling and Underground Space Technology, 2018, 77188-203 J]

[16] KhanlariG, MeybodiR G, MokhtariE. Engineering geological study of the second part of water supply Karaj to Teheran tunnel with emphasis on squeezing problems. Engineering Geology, 2012, 145: 9-17 J]

[17] AganC. Prediction of squeezing potential of rock masses around the Suruç Water tunnel. Bulletin of Engineering Geology and the Environment, 2016, 75(2): 451-468 J]

[18] IasielloC, Guerra TorralboJ C, Torrero FernándezC. Large deformations in deep tunnels excavated in weak rocks: Study on Y-Basque high-speed railway tunnels in northern Spain. Underground Space, 2021, 6(6): 636-649 J]

[19] ZhangC-q, CuiG-j, ZhangY, et al. . Squeezing deformation control during bench excavation for the Jinping deep soft-rock tunnel. Engineering Failure Analysis, 2020, 116: 104761 J]

[20] WangM-n, WangZ-l, TongJ-j, et al. . Support pressure assessment for deep buried railway tunnels using BQ-index. Journal of Central South University, 2021, 28(1): 247-263 J]

[21] AsgharR, LohrasbF, MohammadD. Squeezing rock conditions at phyllite-slate zone in Golab water conveyance tunnel, Iran: A case study. Journal of Central South University, 2017, 24(10): 2475-2485 J]

[22] LiuZ-d, LiD-yuan. Intelligent hybrid model to classify failure modes of overstressed rock masses in deep engineering. Journal of Central South University, 2023, 30(1): 156-174 J]

[23] FennerR. Untersuchungen zur erkenntnis des gebirgsdrucks. Gluckacf, 1938, 74(32): 681-695[J]

[24] KastnerHStatik des tunnel- und stollenbaues, 1971, Berlin Heidelberg, Springer M]

[25] BrownE T, BrayJ W, LadanyiB, et al. . Ground response curves for rock tunnels. Journal of Geotechnical Engineering, 1983, 109(1): 15-39 J]

[26] WangY. Ground response of circular tunnel in poorly consolidated rock. Journal of Geotechnical Engineering, 1996, 122(9): 703-708 J]

[27] Carranza-TorresC, FairhurstC. Application of the convergence-confinement method of tunnel design to rock masses that satisfy the Hoek-Brown failure criterion. Tunnelling and Underground Space Technology, 2000, 15(2): 187-213 J]

[28] SharanS K. Exact and approximate solutions for displacements around circular openings in elastic-brittle-plastic Hoek-Brown rock. International Journal of Rock Mechanics and Mining Sciences, 2005, 42(4): 542-549 J]

[29] ParkK H, TontavanichB, LeeJ G. A simple procedure for ground response curve of circular tunnel in elastic-strain softening rock masses. Tunnelling and Underground Space Technology Incorporating Trenchless Technology Research, 2008, 23(2): 151-159 J]

[30] AlonsoE, AlejanoL R, VarasF, et al. . Ground response curves for rock masses exhibiting strain-softening behaviour. International Journal for Numerical and Analytical Methods in Geomechanics, 2003, 27(13): 1153-1185 J]

[31] AlejanoL R, AlonsoE, Rodríguez-DonoA, et al. . Application of the convergence-confinement method to tunnels in rock masses exhibiting Hoek-Brown strain-softening behaviour. International Journal of Rock Mechanics and Mining Sciences, 2010, 47(1): 150-160 J]

[32] KirschE G. The theory if elasticity and the need of the strength of materials (trans.). J Assoc Ger Eng, 1898, 42(7): 797-807[J]

[33] CaquotAEquilibre des massifs a frottemeni interne, 1934, Paris, FR, Gauthier-Villars[M]

[34] CaquotA, KeriselJTraite de mecanique des sols, 1940, Paris, FR, Gauthier-Villars[M]

[35] OresteP P. Analysis of structural interaction in tunnels using the covergence-confinement approach. Tunnelling and Underground Space Technology, 2003, 18(4): 347-363 J]

[36] OkeJ, VlachopoulosN, DiederichsM. Improvement to the convergence-confinement method: Inclusion of support installation proximity and stiffness. Rock Mechanics and Rock Engineering, 2018, 51(5): 1495-1519 J]

[37] AnX-x, HuZ-p, SuY, et al. . Initial support distance of a non-circular tunnel based on convergence constraint method and integral failure criteria of rock. Journal of Central South University, 2022, 29(11): 3732-3744 J]

[38] HoekEUnderground excavations in rock, 1980, London, UK, CRC Press: 248-332[M]

[39] ShiC-h, LeiM-f, JiaC-junTunnel mechanics, 2022, Changsha, Central South University Press[M]

[40] GuanB-shuGeneral theory of tunnel mechanics, 1993, Chengdu, Southwest Jiaotong University Press[M]

[41] KabweE, KarakusM, ChandaE K. Proposed solution for the ground reaction of non-circular tunnels in an elastic-perfectly plastic rock mass. Computers and Geotechnics, 2020, 119: 103354 J]

[42] ZhangJ-z, ZhouX-p, YinPeng. Visco-plastic deformation analysis of rock tunnels based on fractional derivatives. Tunnelling and Underground Space Technology Incorporating Trenchless Technology Research, 2019, 85209-219 J]