Three-Dimensional Numerical Analysis of Ground Surface Settlement Caused by Excavation of Curved Tunnel

• Main Authors: LIN, CHU-YING, 林筑瑩
• Other Authors: CHEN, SHONG-LOONG
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/4ccr8x

碩士 === 國立臺北科技大學 === 土木工程系土木與防災碩士班 === 107 === The “Contract CM01 of the Taoyuan International Airport MRT Line, Extension to Chungli Railway Station” was selected for a case study. The finite element software, Plaxis 3D, was used for 3-dimensional model analysis. A simulation was performed on the curved section of the shield tunnel for the ground surface settlement deformation caused by the excavation. The longitudinal and lateral ground surface settlement deformation curves were compared with in-situ monitoring data. Two rock mass models, Mohr-Coulomb and Hoek-Brown, were introduced. A comparison was made for the ground surface settlement caused by the excavation activities at various stages and on straight and curved sections, as well as for the soil deformation around the inside and outside of the curved section. As far as the constitutive law of soil mass is concerned, the analysis using the Mohr-Coulomb model and that using the Hoek-Brown model showed no distinct difference between the results. The deformation percentage increased steeply within 0.5 tunnel diameter behind the excavation face; and the ground surface settlement caused by tunnel excavation reached its maximum between 3 and 4 tunnel diameters from the excavation face. Overall, the analysis using the Hoek-Brown model produced results that were closet to the in-situ monitoring data regardless in longitudinal profile or lateral cross section, whereas the analysis using the Mohr-Coulomb model produced slightly different result. The shape of overall subsidence trough was similar to the trend observed. For excavation at sections of different shapes, the ground surface settlement at the curve section was slightly smaller than that at the straight section, provided that the soil conditions and construction conditions were the same at both the curved and straight sections.