Herein, a largescale tunnel structural model
experimental system is established. First, loaded damage tests are conducted on
tunnels without support, supported by shotcrete of various thicknesses, and supported
by secondary lining through structural tests to validate the feasibility of the
load structure model of the shotcrete layer using the total safety factor
method and its calculation method. The physicomechanical
parameters of each material in the model test are then clarified through
triaxial tests of the surrounding rocks and fine sand materials. The entire
loaded damage process of the tunnels without support, supported by shotcrete of
various thicknesses, and supported by secondary lining, is simulated. The
designed bearing capacity of the shotcrete and secondary linings is determined
according to tunnel failure states. The stress and strain of the surrounding
rocks, internal and external strain of the shotcrete layers, and displacement
of the shotcrete layers are monitored. Finally, the deformation and stress
characteristics of shotcrete and secondary linings are analyzed for determining
the bearing capacity of these materials. Comparing the results with the
calculated results using the total safety factor method shows the following:
(1) The stress of the shotcrete layer exhibits a small eccentric compressive
stress. The cohesion between the shotcrete lining and surrounding rock mass can
transfer the shearing force in the rock mass, reducing the bending moment and
greatly improving the compressive strength of the shotcrete lining. The
designed bearing capacity of the shotcrete lining is higher than that of the
secondary lining under the same thickness. (2) The designed bearing capacities
of the shotcrete lining with thicknesses of 2 and 4 cm are 27.0% and 22.9% higher, respectively, than the
theoretical calculation results by the total safety factor method, indicating
the rationality of the calculation model of the bearing capacity of the
shotcrete lining by the total safety factor method.
XIAO Mingqing
,
XU Chen
,
CUI Lan
,
SHENG Qian
,
CHEN Jian
,
XIE Biting
,
WU Peng
. Experimental Study of Bearing Capacity of Shotcrete
Lining Based on Total Safety Factor Method[J]. Tunnel Construction, 2024
, 44(3)
: 464
-474
.
DOI: 10.3973/j.issn.2096-4498.2024.03.004
