Open AccessStudy on construction mechanics of in-situ expansion of ultra-large flat tunnel in collapse section of an existing tunnel
Author(s) -
Yulong Song,
Shi Bo-ran,
Hui Liu,
Ma Zhi-guo,
He Bin,
Yong Yuan,
Haitao Yu
Publication year - 2020
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.179
H-Index - 26
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/570/2/022068
Subject(s) - geotechnical engineering , excavation , settlement (finance) , deformation (meteorology) , geology , computer simulation , arch , section (typography) , engineering , structural engineering , mechanics , physics , oceanography , world wide web , computer science , advertising , business , payment
To meet the needs of the transportation, a tunnel in Fujian Province was expanded in situ to form an ultra-large flat tunnel. In some sections, a large-scale collapse has occurred during the original tunnel construction, which brings a huge risk for the expansion construction. Based on the above background, the theoretical formula is used to calculate the spatial distribution of the collapse, and the dynamic construction mechanical characteristics of the CRD method are studied through numerical analysis and field tests. The results show that: (1) curves of the surface settlement are presented small in both ends while big in the middle, and the settlement center appears above the left side of the tunnel centerline, and the surface settlement caused by the excavation of the upper bench is the largest; (2) the surrounding rock disturbance range is 0.5 times of the tunnel diameter in front and rear of the tunnel. The deformation of the left spandrel of the tunnel is the largest; (3) there are two "V" shaped shear plastic areas in the arch of the tunnel, which is deep into the surrounding rock. During the tunnel construction, the monitoring results of surface settlement, surrounding rock, and support system deformation are in good agreement with the numerical simulation results, which verifies the reliability of the numerical simulation. The research results can provide a reference for the further study of the stability of surrounding rock during the expansion construction of the ultra-flat section tunnel and provide some reference for similar projects in the future.