Through the pullout test of rock bolt and direct shear test of cementation plane between grout and rock, the bond strength parameters between borehole wall and grout and that between grout and rock were obtained respectively. Test results show that the bond strength of cementation plane between grout and rock is dependent on the roughness of cementation plane when the integrity and homogeneity of rock are good. When the strength of hard rock is high, it has strong resistance ability to lateral impact of drilling bit, therefore, the borehole wall of shaped anchor bore is smooth. Contrarily, when the strength of soft rock is low, it has weak resistance ability to lateral impact of drilling bit, as a result, the borehole wall of shaped anchor bore is rough, which enhances ultimate load capacity of cementation plane between grout and rock in the interior embedment section of soft rock anchor cable, and decreases the probability of debonding failure of the interface. Because the influence of borehole wall roughness on the bearing capacity of rock anchor is very obvious, it should be taken into account reasonably in the design and revision of technical specification for prestressed anchors in the future.
Key words
road engineering /
prestressed anchor /
experimental research /
cementation plane /
shear strength /
borehole wall roughness
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