7 CONCLUSIONS
In this paper, similar simulation materials are used for prefabricating
specimens with holes and anchors, and laboratory uniaxial compression
tests are carried out. The strength, deformation characteristics, and
the laws of crack propagation are studied by using the CT scan, and the
coupled stress-damage simulation tests are carried out by using the 3DEC
numerical simulation method. The damage evolution process of the
specimens with bedding and holes under the action of support structures
is discussed.
The support structures can improve the uniaxial compressive strength of
the specimens, but different support structures exhibit different
degrees of supporting effects on the strength of the specimens. The
bolts can significantly improve the strength of the specimens, but the
supporting effects of concrete and steel arches are not evident. With
different bedding angles, the support structures also show different
strength enhancement effects on the specimens. The support structures
demonstrate a better effect on improving the strength of the surrounding
rock of the specimens with a bedding angle of 90° than the specimens
with a bedding angle of 0°.
Concrete and steel arches can induce support pressure on the tunnels,
effectively prevent the holes from peeling, spalling off and other
damages and help maintain the integrity of the holes. The existence of
bedding surfaces can affect the failure process of the rock mass and the
distribution of the secondary cracks, but it cannot affect the final
failure mode.
The analytical formulas related to the stress and the displacement of
the surrounding rock in the anchored area and the non-anchored area
under the action of supporting structures are discussed herein. Based on
the test results, it is concluded that the bolts primarily realize the
anchoring effect by changing the stress state of the surrounding rock in
the anchoring area and by improving the mechanical parameters of the
surrounding rock. The anchoring area demonstrates the functions of
weakening, arresting, and changing the propagation path of cracks, which
thus improves the bearing capacity of the surrounding rock.