To investigate the characteristics and influencing
factors of the large deformation in the tuff stratum of the long and highaltitude
tunnels located in the QinghaiTibet Plateau, the field
investigation, monitoring data analysis, and numerical simulation are adopted
to analyze the characteristics of stress distribution, deformation, and failure
of large deformation section and discuss the influencing factors for large
deformation in highaltitude area. The research and
analytical results show the following: (1) The horizontal tectonic stress field
is the main stress field in the large deformation section of Ailashan tunnel,
and its magnitude is 2.12~2.8 times that of gravity stress field. (2) The
deformation failure characteristics of the primary support are mainly
manifested as cracking, falling blocks, steel frame distortion, and boundary
intrusion. (3) There are 55 cracks with different lengths, widths, depths, and
directions on the left and right sidewalls of the secondary lining. (4) The inverted
arch is dominated by the central uplift, with a maximum uplift of 382 mm, while
the uplift is uneven and the bending failure occurs. (5) The settlement of the
crown is 268.80 mm, the maximum horizontal convergence is 924.9 mm, and the
maximum daily deformation rate is 110.27 mm. The large deformation is
characterized by large amount, fast rate, long duration, and concentrated
location. (6) The initial high ground stress field and the lithologic
conditions of soft tuff are the main influencing factors for the large
deformation of the Ailashan highway tunnel, and the construction method of the
original twobench method, the supporting time, and the
insufficient stiffness of the supporting structure are the important
influencing factors for the large deformation.
GONG Haijun, ZHAO Gengpeng, YAN Jian, WANG Bo, ZHANG Yangyang, LI Zeng
. Characteristics and Influencing Factors of Large
Deformation of Ailashan Tunnel of SichuanTibet Highway[J]. Tunnel Construction, 2021
, 41(S2)
: 129
-136
.
DOI: 10.3973/j.issn.2096-4498.2021.S2.016
