Presently, traditional strengthened support is still
the main choice in soft rock large deformation projects. In this study, the
necessity of yielding support for large squeezing deformation is analyzed. The
traditional rigid support and retractable steel arch are not feasible for
controlling the large squeezing deformation of the tunnel, especially when the
deformation δ is greater than 500 mm. 〖HJ1.7mm〗The relevant results of the yielding anchor bolt and prestressed
yielding anchor cable in five projects confirm their effectiveness in
controlling the large squeezing deformation of soft rock. First, the design
concept and working principle, are introduced Second, (yielding anchor bolt and
prestressed yielding anchor cable are compared. The prestressed yielding anchor
cable is recommended owing to its construction and force performance). The
anchor bolt and anchor cable parameters, anchor head form, and anchor cavity
position of yielding support are introduced. Third, the economic benefit of
yielding support is discussed; the comparison and estimation results indicate
its costefficiency. Fourth, some problems in
calculating and analyzing the soft rock tunnel with large squeezing deformation
are explained: (1) the mode selection of twoand threedimensional analyses; (2) the geometric nonlinearity; (3) the
coupling interaction between creeptime effect and
rheological mechanical properties of nonlinear nonsteady viscoelastic
surrounding rock; (4) development and application of specific software for
analyzing the coupling effect between geometric and material nonlinearity.
Fifth, the research works on the coupling effect are summarized. Finally, the
following suggestions are put forward for further research. (1) Vast amount of
data should be collected from rheological tests and tunnel field measurements,
and numerical simulation should be conducted to provide more feasible methods
for predicting large squeezing deformation. (2) The threedimensional nonlinear viscoelastic rheological mechanical
characteristics should be introduced and expanded. Furthermore, the appropriate
rheological constitutive model should be adopted. (3) The test methods,
numerical calculating methods, and theoretical calculation should be
integrated. A more detailed study on nonlinear rheological mechanical
characteristics of squeezing deformation of different soft surrounding rocks
should be conducted. (4) The multifield coupling should be considered when
conducting indepth analysis on large squeezing
deformation. (5) The study is based on soft rock, and the proposed theory is
based on continuous medium, which does not suit for large deformation failure
of soft clay tunnel. However, it should be considered an extended research aspect.
SUN Jun
,
JIANG Yu
,
WANG Bo
,
FAN Yong
. Nonlinear Rheological Properties and Yielding Support
Technology for Large Squeezing
Deformation of Soft Rock Tunnel with High Ground Stress[J]. Tunnel Construction, 2021
, 41(10)
: 1627
-1633
.
DOI: 10.3973/j.issn.2096-4498.2021.10.001
