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Geomechanics and Engineering Volume 30, Number 4, August25 2022 , pages 325-336 DOI: https://doi.org/10.12989/gae.2022.30.4.325 |
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Analysis of surface settlement troughs induced by twin shield tunnels in soil: A case study |
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Chang-Yoon Ahn, Duhee Park and Sung-Woo Moon
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Abstract | ||
This paper analyzes the ground surface settlements induced by side-by-side twin shield tunnels bored in sedimentary soils, which primarily consist of sand with clay strata above the tunnel crown. The measurements were obtained during the construction of twin tunnels underneath the Incheon International Airport (IIA) located in Korea. The measured surface settlement troughs are approximated with Gaussian functions. The trough width parameters i and K of the settlement troughs produced by the first and second tunnel passings are determined, along with those for the total settlement trough. The surface settlement troughs produced by the first shield passing are reasonably represented by a symmetric Gaussian curve. The surface settlement troughs induced by the second shield tunnel display marginal asymmetric shapes at selected sections. The total settlement troughs are fitted both with a shifted symmetric Gaussian function and the superposition method utilizing an asymmetric function for the incremental trough produced by the second tunnel. It is revealed that the superposition method does not always produce better fits with the total settlement. Instead, the shifted symmetric Gaussian function is overall demonstrated to provide more favorable agreements with the recordings. Therefore, the shifted symmetric Gaussian function is recommended to be used in the design for the prediction of the settlement in clays caused by twin tunneling considering the simplicity of the procedure compared with the superposition method. The amount of increase in the width parameter K for the twin tunnel relative to that for the single tunnel is quantified, which can be used for a preliminary estimate of the surface settlement in clay induced by twin shield tunnels. | ||
Key Words | ||
asymmetrical function; shifted Gaussian curve; surface settlement trough; trough width parameter; twin shield tunnel | ||
Address | ||
Chang-Yoon Ahn: Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-ro, Sageun-dong, Seongdong-gu, Seoul, Korea; HDC Hyundai Development Company, 55, Hangang-daero 23-gil, Yongsan-gu, Seoul, Korea Duhee Park: Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-ro, Sageun-dong, Seongdong-gu, Seoul, Korea Sung-Woo Moon: Department of Civil and Environmental Engineering, Nazarbayev University, 53 Kabanbay Batyr Ave, Nur-Sultan 010000, Kazakhstan | ||