LABORATORY RESEARCH ON ANCHORAGE EFFECT OF FRACTURED ROCK MASS UNDER FREEZING AND THAWING

This paper uses similar materials and makes rock specimens with unanchored and/or anchored prefabricated fissures. Bolts and cracks at 45ånd 90åre made into the anchor rods in the rock specimens. It discusses the regulation of propagation rules, anchorage effects and failure modes of rock samples through uniaxial compression tests after 60 cycles of freeze-thaw cycles with strain monitoring. The test results show the follows. (1)Two types of anchorages have equal effect in cracks supporting before 30 cycles of freeze-thaw cycles. The higher angle between bolts and cracks would have the larger power of anchorage to the cracks. (2)There is a regular form including six stages, cold shrinkage, frost heaving, frost heaving stability, melt-thaw, and rebound stability under natural conditions. Two supporting conditions do not show obvious stages of contraction and rebound. The 90°supporting condition is more effective than the 45°supporting condition. (3)The cement slurry is applied to fractured rock mass by hydraulic grout. It can repair the whole anchoring system. (4)The anchor rod enhances the ability of the fractured rock mass to resist the expansion of the fracture, reduces the suddenness of the fractured rock mass in the fractured rock mass. The failure mode is transformed from tensile damage to tensile shear complex damage.