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Study on Dynamic Response and Long-term Settlement of Water-saturated Weathered Soft Rocks at the Base of Subway Tunnels
(1. Jiangxi Key Laboratory of Geotechnical Infrastructure Safety and Control, East China Jiaotong University, Nanchang 330013;2. Jiangxi Research Center for Underground Space Technology Development and Engineering, Nanchang 330013; 3. Jiangxi Province Architectural Design and Research Institute Group Co., Ltd., Nanchang 330006; 4. Coastal and Urban Geotechnical Engineering Research Center, Zhejiang University, Hangzhou 310058; 5. Shihutang Navigation and Hydropower Hub Branch of Jiangxi Port and Maritime Construction Investment Group Co., Ltd., Nanchang 330008)
Abstract In order to investigate the dynamic response and long-term settlement of water-saturated weathered soft rocks at the base of subway tunnels under the cyclic loading of trains, this paper takes argillaceous siltstones with different degrees of weathering at the tunnel base of the Nanchang Metro as the research subject to carry out indoor dynamic triaxial tests. The paper proposes a mathematical model of cumulative plastic strain of fully-and moderately weathered argillaceous siltstones considering the number of loading, the dynamic stress ratio and the deviatoric stress ratio etc., and conducts a dynamic response analysis through dynamic finite element software. The results show that in combined strata with different degrees of weathering, the vertical influence ranges of dynamic stress and acceleration caused by the train loading are 16.0 m and 7.0 m respectively when the subway tunnel base is located in fully weathered soft rocks, and 11.0 m and 6.0 m respectively when located in moderately weathered soft rocks; also,the peak values of the dynamic stress and the acceleration in fully weathered soft rocks are both greater than those in moderately weathered soft rocks; furthermore, combined with the mathematical model of cumulative plastic strain,the predicted cumulative settlements of the tunnel base located in fully- and moderately weathered soft rocks are 25.68 mm and 17.98 mm, respectively, when the subway has been in operation for 100 years and the train is running at a speed of 110 km/h; and the variation in train running speed has less impact on the long-term settlement of the weathered soft rocks at the base of the tunnel.
Abstract：
In order to investigate the dynamic response and long-term settlement of water-saturated weathered soft rocks at the base of subway tunnels under the cyclic loading of trains, this paper takes argillaceous siltstones with different degrees of weathering at the tunnel base of the Nanchang Metro as the research subject to carry out indoor dynamic triaxial tests. The paper proposes a mathematical model of cumulative plastic strain of fully-and moderately weathered argillaceous siltstones considering the number of loading, the dynamic stress ratio and the deviatoric stress ratio etc., and conducts a dynamic response analysis through dynamic finite element software. The results show that in combined strata with different degrees of weathering, the vertical influence ranges of dynamic stress and acceleration caused by the train loading are 16.0 m and 7.0 m respectively when the subway tunnel base is located in fully weathered soft rocks, and 11.0 m and 6.0 m respectively when located in moderately weathered soft rocks; also,the peak values of the dynamic stress and the acceleration in fully weathered soft rocks are both greater than those in moderately weathered soft rocks; furthermore, combined with the mathematical model of cumulative plastic strain,the predicted cumulative settlements of the tunnel base located in fully- and moderately weathered soft rocks are 25.68 mm and 17.98 mm, respectively, when the subway has been in operation for 100 years and the train is running at a speed of 110 km/h; and the variation in train running speed has less impact on the long-term settlement of the weathered soft rocks at the base of the tunnel.
SHI Yufeng1,
2 CAO Chengwei1,
2 TAN Yifan3 XU Changjie1 etc
.Study on Dynamic Response and Long-term Settlement of Water-saturated Weathered Soft Rocks at the Base of Subway Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(2): 86-95
2022, Vol. 59 