Open AccessStability control measures of soft and broken surrounding rocks of super-large section tunnel constructed using benching tunneling method
Author(s) -
Fei Wan,
Bo Wang,
Chongtao Fu,
Lei Li,
Xuefeng Liu
Publication year - 2021
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/769/3/032082
Subject(s) - arch , quantum tunnelling , geotechnical engineering , stability (learning theory) , deformation (meteorology) , displacement (psychology) , stratum , strength reduction , geology , structural engineering , water tunnel , engineering , materials science , mechanics , physics , computer science , finite element method , psychology , oceanography , optoelectronics , machine learning , psychotherapist , vortex
The tunnel face of the super-large section tunnel constructed using benching tunneling method tends to loss stability in the stratum with very poor surrounding rock grade (grade V). Therefore it is necessary to employ advanced support or optimize bench construction parameters to improve the stability of tunnel construction. In order to determine the stability control measures for the super-large section tunnel constructed using benching tunneling method in soft and broken surrounding rock, a three-dimensional elastoplastic model is established. Taking the extrusion displacement of tunnel face and the failure zone of surrounding rock as indices, the influences of bench height, bench length, circulating footage and other construction parameters and the construction of advanced large pipe shed on tunnel stability were analyzed. The calculation results show that when the tunnel is constructed using benching tunneling method, the surrounding rock within 4.5m in front of the tunnel face and 1.5m above the arch collapses, and the failure develops from the arch top down to the arch foot. The measures such as shortening the circulating footage, shortening the length of the bench and reducing the height of the upper bench have little effect on the stability of the tunnel, and the maximum difference among the strength reduction coefficients of the surrounding rock is 0.1 when the tunnel losses stability. The advanced large pipe shed can significantly improve the stability of benching tunneling method construction. The deformation and failure of the tunnel mainly concentrates in the side wall area, which gradually develops from the arch foot to the wall foot, and the depth of the surrounding rock failure zone is very limited.