Authors:
Jin-xiu YUAN; Dao-yuan WANG;
Abstract:
By conducting a large-scale three-dimensional model test in an outdoor experimental tank, this paper aims to
reveal the effect of the pre-lining method during the full-section excavation and the mechanism of the
progressive failure and instability. Firstly, the test purpose, test site, similar materials, test process and
measuring systems are described in detail. Then, the effect of the pre-lining method is obtained through the
comparative analysis of the internal displacement, surrounding rock pressure and pre-deformation of advanced
core soil. Finally, the mechanisms of progressive failure and instability are explored by studying the instability
process and the deformation evolution under different loadings. The results show that the convergences of vault
and sidewall are decreased by 25% and 80%, the pre-convergence rate is reduced by 20 %~30 % and the
longitudinal influence range of advanced core soil is decreased by nearly 60% under normal load conditions.
The instability process of the tunnel is peeling-slip-collapse of rock mass and the collapse is finally formed
with 2 m depth of sidewall, 1.4 m depth of vault and 1.2 m depth of excavating face. The limit displacement
value of railway double-track tunnel under the geological condition of completely weathered V-grade granite
is given.
Keywords:
Tunnel engineering, Weak and broken surrounding rock, Pre-lining method, Effect
of implementation, Progressive failure, Model test