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Study on Effect of Backfilling Grouting Thickness on Anti-floating of the Shield Tunnel
(1 Hangzhou Metro Group Co., Ltd., Hangzhou 310017; 2 PowerChina Huadong Engineering Corporation Limited, Hangzhou 311122;3 Zhejiang Engineering Research Center of Smart Rail Transportation, Hangzhou 311225; 4 College of Civil and Transportation Engineering, Hohai Unversity, Nanjing 210098)
Abstract Sand liquefaction will occur and result in tunnel uplift and even damage under the effect of earthquake when the shield tunnel passes through sandy soil stratum. The dynamic response of the surrounding liquefied strata before and after backfill grouting of the shield tunnel is studied by shaking table model test and numerical simulation, and it shows the main damage pattern of the shield tunnel is liquefaction induced uplift. Backfill grouting can ′t significantly alleviate the liquefaction tendency of subsoil, but the uplifting displacement of the tunnel model can be remarkably reduced if peak acceleration keeps unchanged. The numerical simulation and test results show that the sand liquefaction firstly occurs at the surface and shallow soil layer, and the sand liquefaction degree gradually decreases with the increase of depth, that is to say increase of tunnel buried depth is conducive to reducing liquefaction degree. Integrity is formed by backfilling grouts and tunnel structure and this increases the overlying effective pressure indirectly and can offset the uplift induced by foundation liquefaction. For the shield tunnel with a diameter larger than 6.2 m, obvious anti-uplift effect will be obtained if the grout penetration radius is larger than 1.0 m in condition of grouting reinforcement.
Abstract：
Sand liquefaction will occur and result in tunnel uplift and even damage under the effect of earthquake when the shield tunnel passes through sandy soil stratum. The dynamic response of the surrounding liquefied strata before and after backfill grouting of the shield tunnel is studied by shaking table model test and numerical simulation, and it shows the main damage pattern of the shield tunnel is liquefaction induced uplift. Backfill grouting can ′t significantly alleviate the liquefaction tendency of subsoil, but the uplifting displacement of the tunnel model can be remarkably reduced if peak acceleration keeps unchanged. The numerical simulation and test results show that the sand liquefaction firstly occurs at the surface and shallow soil layer, and the sand liquefaction degree gradually decreases with the increase of depth, that is to say increase of tunnel buried depth is conducive to reducing liquefaction degree. Integrity is formed by backfilling grouts and tunnel structure and this increases the overlying effective pressure indirectly and can offset the uplift induced by foundation liquefaction. For the shield tunnel with a diameter larger than 6.2 m, obvious anti-uplift effect will be obtained if the grout penetration radius is larger than 1.0 m in condition of grouting reinforcement.
LI Qiang1 GAN Penglu2,
3 ZHONG Xiaochun4
.Study on Effect of Backfilling Grouting Thickness on Anti-floating of the Shield Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(6): 27-35
2019, Vol. 56 