To avoid arch large deformation and ground collapse
when tunneling through fracture zones, an excavation support system of the
prestressed anchor bolt and bench method is designed for tunnels crossing
fracture zones. The system is numerically modeled and compared with the hollow
grouting anchor bolt and the central diaphragm (CD) method, and field tests are
performed. The results reveal the following: (1) The prestressed anchor bolt
and bench method have an excellent control effect on the surrounding rock
deformation; simulation results show that the controlling effect of crown
settlement, horizontal displacement, and excavation disturbance range of the
surrounding rock in the recommended methods is superior. After arch
penetration, the final surrounding rock deformations using the bench method and
the CD method are stable at 6.8 mm and 11.5 mm, respectively. (2) The active
support site monitoring results indicate that the settlement of the crown is
mainly concentrated during the excavation of guide hole No. 1, and the
evolution process can be divided into acceleration, development, and stability stages.
(3) The grating steel frame′s stress is primarily compressive,
with the crown stress exceeding 90 MPa; the axial force of the anchor bolt
evolves through three stages with tunnel excavation: prestress loss,
fluctuation, and stability, with the change not exceeding 0.1 kN/d after
stabilization.
MA Xingzhi
,
ZHONG Ke
,
XU Dongming
,
,
ZHAI Zhaoxi
,
ZHAN Jiawang
,
FANG Yi
. Comparative Analysis of Excavation and Support Schemes
for ShallowBuried Large CrossSection
Tunnels Crossing Fracture Zones: a Case Study of Chuangzhigu Station on Qingdao Metro Line 6[J]. Tunnel Construction, 2022
, 42(6)
: 1061
-1070
.
DOI: 10.3973/j.issn.2096-4498.2022.06.014