To explore the stress
characteristics of the anchor bolt support in small-section TBM tunnels and assess the rationality of the support
parameters, a case study is conducted on the Tongcheng pumped storage power station′s self-flow drainage tunnel project in Anhui province, China. The rock mass
mechanics method and numerical simulation method are used to calculate the
anchor internal force and surrounding rock displacement under the Grade Ⅲ surrounding rock conditions. Three monitoring sections are selected
immediately following the TBM in the TBM excavation section of the tunnel, and
the anchor stress meter and multi-point displacement
meter are used to monitor the anchor internal force and surrounding rock
displacement under actual working conditions. After comparative analysis of the
results obtained by the three methods, conclusions are drawn as follows: (1)
The changing trends of the axial force calculated by the numerical simulation
method and the geotechnical method are similar. The maximum axial force value
appears in the middle of the anchor bolt, which is consistent with the neutral
point theory. The maximum axial force is 4.78 kN. (2) The changing trends of
the surrounding rock displacement obtained by the three methods are similar,
with the maximum displacement appearing on the surface of the tunnel
surrounding rock, and the smallest displacement of the surrounding rock inside
the rock layer, with the maximum displacement being 2.03 mm. Furthermore,
compared with the existing research results on the structural stress of larger
cross-section tunnels, it is shown that compared with
larger cross-section tunnels, the anchor bolt axial
force and surrounding rock deformation of small-section
TBM tunnels are smaller, and the anchor support function has not been fully
utilized. Based on this, optimization suggestions are put forward to delay,
reduce or cancel the anchor support of small-section
TBM tunnels.
WANG Wei, YANG Guang, REN Taozhe, DU Kenan, LYU Fengying, WANG Junjie
.
Stress Characteristics and Parameter Optimization of Anchor Bolt Support in Small-Section
TBM Tunnels
[J]. Tunnel Construction, 2024
, 44(S1)
: 237
-246
.
DOI: 10.3973/j.issn.2096-4498.2024.S1.026
