Study on mechanical properties of a layered rock with holes under the
support structure
Abstract
In order to analyze the action mechanism of the tunnel support structure
and its supporting characteristics in a layered and weak rock tunnel, an
experimental study on seven types of support situations, namely, rough
tunnel, systematic rock bolt support, systematic rock bolt, and
shotcrete support, systematic rock bolt and shotcrete and steel arch
support, steel pipe support, steel pipe, and shotcrete support, and
steel pipe and shotcrete and steel arch support, has been conducted. The
mechanical, deformation, and support characteristics of the rock with
holes under uniaxial compression tests have been studied. The
experimental results demonstrated that (1) all different support
structures can enhance the uniaxial compressive strength of the
specimens, but different support structures exhibit different effects.
The rock bolt can significantly enhance the strength of the specimen,
but the supporting effect of concrete and steel arches is not evident.
(2) The bedding direction directly affects the strength enhancement of
the support structure to the specimen, the support strength of the
support structure to the rock with a bedding angle of 90° is higher than
that of the rock with a stratification angle of 0°, and the bedding
affects the failure process of the rock mass and the secondary crack
distribution. (3) By using the CT scan of the specimens after the test,
it is found that the bolt’s crack arrest effect on cracks is the result
of weakening, shearing, and arresting of cracks in the anchorage zone;
the crack arrest effect is related to the size of the anchorage zone,
and the larger the range of the anchorage zone, the better the crack
arrest effect.