To clarify the adverse
effects induced by lateral unloading of an adjacent foundation pit excavation,
a shield tunnel structure model is established based on the joint force-displacement equation and the interaction relationship between a
metro shield tunnel and a foundation pit in Hangzhou, China. Then, an elaborate
stratum-shield tunnel finite numerical simulation
method is used to explore the force and deformation mechanisms of the segments
and joints of the existing shield tunnel caused by lateral unloading. The
effectiveness of the proposed method is validated by comparison with field
monitoring data. The results reveal the following: (1) The deformation of the
shield tunnel can be divided into a convergence deformation zone and a ring
dislocation zone. (2) A 7.5 mm vertical settlement and an 8.5 mm horizontal
displacement towards inner foundation pit are induced, and the displacement
along longitudinal direction shows a stepped shape due to dislocation between
segmental rings. (3) The segmental ring exhibits an elliptical convergence
deformation, and the longitudinal joints at the tunnel crown and the arch waist
open towards inside and outside of the tunnel, respectively. The maximum in-ring compression stress reaches 7.66 MPa, leading to leakage of the
longitudinal joints at the tunnel crown and compression crack at the arch
waist. (4) Dislocations between adjacent rings occur at circumferential joints,
leading to leakage. (5) Foundation pit dewatering is a primary factor affecting
tunnel displacement, which contributes 82% of settlement and 46% of horizontal
displacement, respectively.
RUAN Hengfeng
,
LIANG Rongzhu
,
KANG Cheng
,
LI Zhongchao
,
CAO Shi′an
,
DING Zhi
. Elaborate Numerical
Modeling of Metro Shield Tunnel Structure Deformation
Induced by Lateral Foundation Pit Excavation[J]. Tunnel Construction, 2024
, 44(S2)
: 245
-255
.
DOI: 10.3973/j.issn.2096-4498.2024.S2.025
