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| Numerical simulation and analysis of construction behavior for
dualarch tunnel tunneling overlapped to existing tunnel |
| School of Civil Engineering, Southwest Jiaotong University, Chengdu， Sichuan 610031, China |
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Abstract Considering Yashan dualarch tunnel with characteristics of shallow buried depth, unsymmetrical load and closely adjacent to an existing smalldistance tunnel, the two construction processes of a dualarch tunnel were simulated by FEM under the sequences of ″deep to shallow″ and ″shallow to deep″ to tunnel the mainhole respectively. The deformation stress condition of dualarch tunnel surrounding rock and lining of existing smalldistance tunnel and the displacement of middlewall in the two tunneling sequences were analyzed and compared. The results indicate that the deformation rule of dualarch tunnel in the two construction processes is basically consistent. The largest vault settlement occurs at the deeper buried mainhole, and the largest horizontal displacement appears at the junction of shallow buried left mainhole and middlepilot with values of 3.19 mm and 1.17 mm, respectively. Due to unsymmetrical load, the middlewall subjects to compression load with small eccentricity since it is completed. However, the initial deflection of middlewall is corrected gradually when either mainhole is excavated. After rock mass excavation of the dualarch tunnel, the smalldistance tunnel lining between spandrel and haunch occurs displacement with moving toward the dualarch tunnel, and the displacement of ″deep to shallow″ is 0.01~0.02 mm larger than that of ″shallow to deep″.
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2016, Vol. 37 
