When the tunnel boring machine(TBM) used in
Daliangshan tunnel of Leshan-Xichang expressway bored to parallel
heading No.1 in the layered silty mudstone strata, the surrounding rock
loosened and fell, and large deformation occurred. As a result, to investigate
the damage characteristics of the surrounding rock during TBM construction in
layered silty mudstone strata and explore feasible support methods, the field
monitoring and numerical simulation methods are adopted to study the damage
process and the factors affecting the stability of the surrounding rock in TBM
tunneling in such strata. On this basis, the research of TBM support method is
carried out. The results show the following: (1) The deformation and plastic
zone of the surrounding rock increase after the shield passes by, the damage of
the surrounding rock intensifies, resulting in uncontrollable surrounding rock
deformation and plastic zone development under the support of anchor bolt and
steel arch frame. The protection zones by anchor bolt and steel arch frame are
the key points. (2) The stability of the surrounding rock in such strata is
mainly affected by the combination of the layered rock mass formation, high insitu stress, and the unique support method of the TBM. The numerical
simulation results of support optimization show that after increasing the rock
bolt length and changing the sprayed concrete support method into primary spraying
and secondary spraying, the deformation and plastic zone of the surrounding
rock have been controlled, the damage has been decreased, and stability of the
surrounding rock have been improved, reaching a good construction effect.
FANG Xinghua, YAO Jie, XU Zhen, LI Xiaowei, XIA Yimin, YANG Junsheng
.
Stability and Support Methods of Surrounding Rocks of
Tunnel Boring
Machine Tunnel in Layered Silty Mudstone Strata
[J]. Tunnel Construction, 2021
, 41(S2)
: 320
-328
.
DOI: 10.3973/j.issn.2096-4498.2021.S2.041
