To investigate the geological and structural
characteristics of the taluslike rock mass, analyze the
mechanisms of large deformation collapse during tunnel excavation, and explore
the tunnel stability, a case study is conducted of Tayi tunnel of the JianshuiYuanyang highway. Detailed study is carried out on the basic structural
characteristics of taluslike rock mass, engineering
problems during tunnel construction, and support measures using site survey,
field investigation, deformation measurement, and surrounding rock pressure
monitoring. The results show the following: (1) The surrounding rock mass has a
complex and loose structure, which is easily affected by the excavation
perturbation. The influence range of deformation is about 30 m behind the
tunnel face. (2) Some disasters such as large deformation, collapse of excavation
face, failure of the primary lining, and water inrush are easy to occur after
excavation. The surrounding rock deformation and stress increase rapidly due to
tunnel excavation, the maximum deformation is about 350 mm, the maximum
surrounding rock pressure is 350 kPa, and the internal force of steel arch
frame exceeds 250 MPa. It is also found that the excavation of the middle and
lower benches can obviously reduce the pressure and deformation around the
upper bench. The deformation and pressure along the tunnel section are
extremely uneven due to the uniform excavation profile. The safety and
stability of tunnel construction in the taluslike rock
mass can be guaranteed by enlarging the reserved deformation, improving the
type of steel arch and the strength and stiffness of the primary support,
installing doublelayer steel arch, strengthening the
arch foot support, and implementing advance reinforcement and grouting.
CHENG Hao, CAO Zhensheng, ZHANG Shaoqiang, TANG Weiyu, LI Xiaochang, ZHANG Zixin
. Structural Characteristics of TalusLike
Rock Mass and Tunnel Stability Analysis: a Case Study
of Tayi Tunnel of JianshuiYuanyang Highway[J]. Tunnel Construction, 2021
, 41(S2)
: 274
-283
.
DOI: 10.3973/j.issn.2096-4498.2021.S2.035
