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Abstract In light of that the periodical temperature changing leads to mechanical properties deterioration of rock bolts during the snowmelt period in spring，the relationship between bearing capacity of rock bolts and freeze-thaw cycles was studied. The freeze-thaw cycling experiments were conducted first for rock bolt specimens under different freeze-thaw cycles；and then the pull-out experiments were carried out. The displacement，stress and failure load of bolt，stress of rock，shear strength at the bolt-grout interface were investigated；the failure mode and main destruction factor under freeze-thaw conditions were studied with load transfer mechanism. It is shown that the elastic modulus and strength of mortar decreases along with the increase of freeze-thaw cycles；the mortar near the loading end splits ahead of time and accelerates load transferring to the inside of bolt；the internal stresses of bolt and bond increase. The ultimate bearing capacity of bolt decreases while the deformation of bolt increases under freeze-thaw conditions；the inflection point in load-displacement curve and horizontal segment in slipping curve of bolt will appear in advance along with the increase of freeze-thaw cycles.
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Received: 22 April 2013
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2014, Vol. 33 
