Damage Mechanism of Anchor Bolt Structure Under Dynamic and Static Pull-out Loads
Research on damage mechanism of anchor bolt structure under dynamic and static pull-out is very important to the design and construction,the numerical calculation model was established based on elastoplastic damage model of anchorage agent and bond-slip model of anchorage interface,and parameter"static ratio"and sinusoidal dynamic load model with variable amplitudes were also introduced.The numerical model was verified by laboratory test firstly taking deformation curve of anchor bolt as example,then the damage mechanisms of anchor bolt structures with different interface strengths under composite loads were studied,which includes the damage process,mode and characteristics,and the influence of static ratio was also analyzed simultaneously.Results show that three damage modes of anchor bolt structure are included under influence of anchorage interface strength,namely single damage mode(anchorage interface sliding),three phases damage mode(oblique&horizontal cracks of anchorage agent and interface sliding),two phases damage mode(oblique and horizontal cracks of anchorage agent).Anchor bolt slides with the anchorage interface when the interface strength is small,while the oblique crack of anchorage agent generates with the increase of interface strength,and the dip angle becomes smaller,the oblique crack zone becomes larger,while the oblique crack doesn't extend to anchorage interface.Bearing capacity of anchor bolt structure increases with the increase of static ratio when it's less than 70%,while it decreases gradually on the contrary.Ultimate displacement of anchor bolt structure and cycle time of dynamic load decrease with the increase of static ratio.Peak load of anchor bolt structure under composite loads is less than the static condition,and the decrease is apparent of post-peak bearing capacity.In engineering application,strength increases of anchorage interface and agent are suggested,and decrease of static ratio as well,especially the reduction of dynamic impact load.
tunnelanchor bolt structurecomposite pull-outdamage mechanisminterface strengthstatic ratio
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