Abstract
In roadways with high ground stress or burial depths, the joints distributed within rock formations are subject to complex stresses and interlayer misalignments frequently. Rock bolts and cable bolts anchored in the rock formations are subject to tensile and shear forces. Most of the bolts used in roadway engineering are local anchored, resulting in insufficient shear strength at the bolt free end close to roadway surface and increasing bolts breaking. The anchor cable and C-shaped tube (ACC) is a highly prestressed cable bolt that can withstand high shear force in its free end. This paper examines the effect of the relationship between C-shaped tube length and joint location on the shear resistance of ACC by double shear tests. To fully exploit the ACC’s shear resistance, the C-shaped tube ends should be at least 30 cm beyond the joint. The effect of preload and concrete spray thicknesses on roadway deformation and plastic zone is investigated by numerical simulation. Results show that ACC and concrete spraying layer can form a stable extruded arch structure, so that the broken and soft rock within the loosen zone is in three-dimensional-stress state, effectively improving surrounding rock properties and controlling its deformation size. Based on these results, the ACC support design method is proposed.
Highlights
As coal resources are developed and exploration, many mines are gradually developing to depths of 1000 m and more, and deep roadways will face complex ground stress, water-rich, and other geological conditions, exhibiting obvious nonlinear large deformation characteristics [1]
The relationship between the location of the C-shaped tube and the joint surface is investigated through double shear experiments, the design guidelines for the C-shaped tube length in the support design are determined, and the influence of the preload and concrete spray layer thickness on the plastic zone of the roadway is investigated through numerical simulations
With a hole length of 300 mm in a single concrete block, when the C-shaped tube is more than 30 cm from the joint surface, the test result in this condition was replaced by cable bolt
Summary
As coal resources are developed and exploration, many mines are gradually developing to depths of 1000 m and more, and deep roadways will face complex ground stress, water-rich, and other geological conditions, exhibiting obvious nonlinear large deformation characteristics [1]. The relationship between the location of the C-shaped tube and the joint surface is investigated through double shear experiments, the design guidelines for the C-shaped tube length in the support design are determined, and the influence of the preload and concrete spray layer thickness on the plastic zone of the roadway is investigated through numerical simulations. With a hole length of 300 mm in a single concrete block, when the C-shaped tube is more than 30 cm from the joint surface, the test result in this condition was replaced by cable bolt.
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