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Abstract: When tunnels are constructed in coastal cities, they will inevitably undercross a river. Exploring the influence of rivers on tunnelling-induced deformation in costal soft soil is of great significance for controlling excessive settlement and protecting surrounding buildings. This paper presents a case study of twin tunnels undercrossing a river in soft soil in Hangzhou, China. The soft soil of Hangzhou refers to cohesive soil in a soft plastic or fluid plastic state with high natural water content, high compressibility, low bearing capacity, and low shear strength. Considering the influence of the river, the research region was divided into two parts, inside and outside the river-affected area, based on monitoring data of the Zizhi Tunnel. The development law of surface settlement is divided into three stages. In the first and second stages, the surface settlement within and outside the river-affected area showed a similar trend: the settlement increased and the growth rate of settlement in the second stage was smaller within the river-affected area. In the third stage, the surface settlement continued to increase within the river-affected area, while it converged outside the river-affected area. Within the river-affected area, there was an asynchronization of the sinking rate and stability of vault settlements and surface settlements. A numerical model was established by simulating different reinforcements of the tunnel. The numerical model revealed that the ground movement is influenced by the distribution and amount of the excess pore water pressure. The excess pore pressure was concentrated mostly in the range of 1.0H_t–3.0H_t (H_t is the tunnel height) before the tunnel face, especially within the river-affected area. Inside the river-affected area, the dissipation of excess pore water pressure needs more time, leading to slow stabilization of surface settlement. When undercrossing a river, a cofferdam is necessary to reduce excessive ground deformation by dispersing the distribution of excess pore water pressure.

河流对软土隧道开挖引起的变形的数值分析

[1]BroereW, 2003. Influence of excess pore pressures on the stability of the tunnel face. In: Saveur J (Ed.), (Re) Claiming the Underground Space. A.A. Balkema, Lisse, the Netherlands, p.759-765.

[2]CattoniE, MirianoC, BocoL, et al., 2016. Time-dependent ground movements induced by shield tunneling in soft clay: a parametric study. Acta Geotechnica, 11(6):‍1385-1399.

[3]CesanoD, OlofssonB, BagtzoglouAC, 2000. Parameters regulating groundwater inflows into hard rock tunnels—a statistical study of the Bolmen tunnel in Southern Sweden. Tunnelling and Underground Space Technology, 15(2):153-165.

[4]ChapmanDN, RogersC, HuntL, 2006. Predicting the settlements above closely spaced triple tunnels constructions in soft ground. Geotechnical Aspects of Underground Construction in Soft Ground. Proceedings of the 5th International Conference of TC 28 of the ISSMGE, p.219-224.

[5]ChapmanDN, AhnSK, HuntDVL, 2007. Investigating ground movements caused by the construction of multiple tunnels in soft ground using laboratory model tests. Canadian Geotechnical Journal, 44(6):631-643.

[6]DayMJ, 2004. Karstic problems in the construction of Milwaukee’s deep tunnels. Environmental Geology, 45(6):859-863.

[7]DivallS, 2013. Ground Movements Associated with Twin-Tunnel Construction in Clay. PhD Thesis, City University London, London, UK.

[8]GohATC, ZhangRH, WangW, et al., 2020. Numerical study of the effects of groundwater drawdown on ground settlement for excavation in residual soils. Acta Geotechnica, 15(5):1259-1272.

[9]HajjarM, HayatiAN, AhmadiMM, et al., 2015. Longitudinal settlement profile in shallow tunnels in drained conditions. International Journal of Geomechanics, 15(6):1-12.

[10]HöfleR, FillibeckJ, VogtN, 2008. Time dependent deformations during tunnelling and stability of tunnel faces in fine-grained soils under groundwater. Acta Geotechnica, 3(4):309-316.

[11]HuangJ, ZhangDL, 2004. Analysis of large deformation regularity in stratum above metro tunnel. Rock and Soil Mechanics, 25(8):1288-1292 (in Chinese).

[12]LiZ, LuoZJ, XuCH, et al., 2019. 3D fluid-solid full coupling numerical simulation of soil deformation induced by shield tunnelling. Tunnelling and Underground Space Technology, 90:174-182.

[13]LiangY, ZhangJ, ChenXY, 2021. The impact of excess pore pressure on the support stability of a shield when tunnelling in sand stratum. KSCE Journal of Civil Engineering, 25(8):3136-3145.

[14]LiuW, ZhaoY, ShiPX, et al., 2018. Face stability analysis of shield-driven tunnels shallowly buried in dry sand using 1-g large-scale model tests. Acta Geotechnica, 13(1):1-13.

[15]LiuW, WuB, ShiPX, et al., 2021. Analysis on face stability of rectangular cross-sectional shield tunneling based on an improved two-dimensional rotational mechanism. Acta Geotechnica, 16(11):3725-3738.

[16]MaL, 2015. Application research of steel sheet pile cofferdam in water-pier reinforcement engineering. Transportation Science & Technology, (3):31-34 (in Chinese).

[17]MairRJ, 1996. Settlement effects of bored tunnels. International Conference of Geotechnical Aspects on Underground Construction in Soft Ground, p.43-53.

[18]O’ReillyMP, NewBM, 1982. Settlements above tunnels in the United Kingdom‍–‍their magnitude and prediction. Proceedings of Tunnelling’82 Symposium, p.‍173-181.

[19]PeckBR, 1969. Deep excavations and tunneling in soft ground. Proceedings of the 7th International Conference on Soil Mechanics and Foundations Engineering, p.225-290.

[20]SahooJP, KumarB, 2019. Support pressure for stability of circular tunnels driven in granular soil under water table. Computers and Geotechnics, 109:58-68.

[21]ShahinHM, NakaiT, IshiiK, et al., 2016. Investigation of influence of tunneling on existing building and tunnel: model tests and numerical simulations. Acta Geotechnica, 11(3):679-692.

[22]SogaK, LaverRG, LiZL, 2017. Long-term tunnel behaviour and ground movements after tunnelling in clayey soils. Underground Space, 2(3):149-167.

[23]SuwansawatS, EinsteinHH, 2007. Describing settlement troughs over twin tunnels using a superposition technique. Journal of Geotechnical and Geoenvironmental Engineering, 133(4):445-468.

[24]TangXW, GanPL, LiuW, et al., 2017. Surface settlements induced by tunneling in permeable strata: a case history of Shenzhen Metro. Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 18(10):757-775.

[25]TangXW, LiangJX, LiuW, et al., 2021. Modification of peck formula to predict ground surface settlement of twin tunnels in low permeability soil. Advances in Civil Engineering, 2021:6698673.

[26]WanMSP, StandingJR, PottsDM, et al., 2019. Pore water pressure and total horizontal stress response to EPBM tunnelling in London Clay. Géotechnique, 69(5):434-457.

[27]WeiXJ, ChenWJ, WeiG, et al., 2012. Research on distribution of initial excess pore water pressure due to shield tunnelling. Rock and Soil Mechanics, 33(7):‍2103-2109 (in Chinese).

[28]XuH, LiangZG, 2015. Reinforcement technology of large-scale steel sheet pile cofferdam in soft foundation on the sea. Construction Technology, 44(17):120-123 (in Chinese).

[29]XuT, BezuijenA, 2018. Analytical methods in predicting excess pore water pressure in front of slurry shield in saturated sandy ground. Tunnelling and Underground Space Technology, 73:203-211.

[30]YooC, 2016. Ground settlement during tunneling in groundwater drawdown environment–influencing factors. Underground Space, 1(1):20-29.

[31]YooC, LeeYJ, KimSH, et al., 2012. Tunnelling-induced ground settlements in a groundwater drawdown environment‍–‍a case history. Tunnelling and Underground Space Technology, 29:69-77.

[32]ZhouH, GaoY, ZhangCQ, et al., 2018. A 3D model of coupled hydro-mechanical simulation of double shield TBM excavation. Tunnelling and Underground Space Technology, 71:1-14.