Soft rock large deformation occurred in East Tianshan
extralong highway tunnel crossing F2 fault fracture zone. Accordingly,
the theoretical analysis, numerical simulation, onsite
monitoring, and statistical analysis are employed to investigate the control
standards of primary support deformation of tunnel constructed by twobench reserved core soil method and threebench
method. Then the phased early warning method of primary support deformation is
proposed. The results reveal the following: (1) The reserved deformation of
East Tianshan tunnel crossing F2 fault fracture zone is recommended to be 60~80
cm, which can meet the construction requirements. (2) The primary support
deformations induced by top heading and lower bench excavation using twobench reserved core soil method are recommended to be 60% and 40% in
total deformation, respectively, whereas those induced by top heading, middle
bench, and lower bench excavation using threebench
method are recommended to be 20%, 65%, and 15% in total deformation,
respectively. (3) Grades Ⅰ, Ⅱ,
and Ⅲ early warning should be started respectively when
the primary support deformation not exceed reserved deformation, exceeds the
reserved deformation but not exceed 5% of the secondary lining design
thickness, and not exceed 10% of the secondary lining design thickness. Normal
construction can be operated in case of grade Ⅰ early
warning, treatment measures such as controlling excavation advance and bench
length, setting up retaining arch in time, and closing primary support as soon
as possible shall be undertaken in case of grade Ⅱ early warning, and short bench or micro bench method shall be further used in
case of grade Ⅲ early warning.
HUANG Jiefang, HUANG Mingli, TAN Zhongsheng
. Phased Control Standards of Primary Support
Deformation of East Tianshan Tunnel Crossing Fault Fracture Zone[J]. Tunnel Construction, 2022
, 42(S1)
: 155
-165
.
DOI: 10.3973/j.issn.2096-4498.2022.S1.018
