• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1105-1123
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• 2018

The main risk factors of tunnel excavation through urban areas are ground settlement and surface sink which caused by ground conditions, excavation method, groundwater condition, excavation length, support method, etc. In the process of ground settlement assessment, the numerical analysis should be conducted considering the displacement and stress due to tunnel excavation. Therefore a technique that can simplify such process and easily evaluate the influence of tunnel excavation is needed. This study focused on the tunnelling-induced ground settlement which is main consideration of underground safety impact assessment. The parametric numerical analyses were performed considering such parameters as ground conditions, tunnel depth, and lateral distance from tunnel center line, etc. A simplified ground settlement evaluation chart was suggested by analyzing tendency of ground subsidence, lateral influence area and character by depth. The applicability of the suggested settlement evaluation chart was verified by comparative numerical analysis of settlement characteristics.

• Journal of the Korean Geotechnical Society
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• v.38 no.11
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• pp.149-161
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• 2022

This study selected the indexes for evaluating the damage of the railway embankments due to liquefaction from the earthquake damage cases of railway embankments. The study correlated the selected indexes and the settlement of the embankment crest from the dynamic numerical analysis. Further, the correlation was used to develop a method for evaluating the liquefaction damage to the railway embankment. The damage cases and damage types were analyzed, and referring to the liquefaction damage assessment method for other structures, the embankment height (H), the non-liquefiable layer thickness (H₁), and the liquefaction potential index were selected as indexes for evaluating the damage. The study performed dynamic effective stress analyses on the railway embankment, and the PM4-Sand model was applied as the constitutive liquefaction model for the embankment foundation ground. The model's validity was first verified by comparing it with the existing dynamic centrifugal model test results performed on the railway embankment. Nine sites where the foundation ground can be liquefied were selected from the data of 549 embankments of the Honam High-speed Railway in Korea. Further, dynamic numerical analyses using four seismic waves as input earthquake load were performed for the selected site sections. The numerical analysis results confirmed the correlation between the evaluation indexes and the embankment crest settlement. A method for efficiently evaluating the damage to the embankment due to liquefaction was proposed using the chart obtained from this correlation.