Stabilization of Deep Roadways in Weak Rocks Using the System of Two-level Rock Bolts

Abstrakt

Large rock mass deformation around deep roadways in the weak rocks was a significant
problem in mining activities in Vietnam and other countries. The excavation of roadways leads to high
releasing stress, which exceeds the peak strength of spalling surrounding rock and causes it to enter the
post-failure stage. Tensile failures then initiate and develop around the roadways, which causes the
fragmentation, dilation, and separation of surrounding rock. The capacity of the primary support system
is low, which results in a severe contraction in the whole section of roadways, which requires finding
solutions to prevent the deformation of rock mass around roadways and technical solutions from
stabilizing for deep roadways. To stability analysis of roadways can be applied analytical, experimental,
semi-experimental, and numerical methods. This paper introduces the prevention mechanism of large
deformation of rock mass around roadways using 2-level rock bolts. The research results show that using
the system of two-level rock bolts can reduce the values of tensile stress on the boundary of roadways
range from 10 to 15% compared with only one. The importance of the total displacement of rock mass on
the boundary of roadways will be reduced from 3.47 to 13.85% using six long cable bolts.