Investigation into Failure Mechanism of Prestressed Anchor Cables Under Concentrated Tension in Contrlling Landslide

Prestressed anchor cable under concentrated tension is often applied in supporting projects of road slope,when designing structure of anchorage,the bond strength of interface between grouting and rock is highly concerned,from investigatings on unstable road slope in mountainous area of south-west China,the weakest part of prestressed anchor cable under concentrated tension was not the interface between grouting and rock.Therefore,eleven grouting materials with different mixture ratios are designed,in which eighty prestressed anchor cables under concentrated tension are embedded in soft rock and hard rock.Then the failure mode of prestressed anchor cables have been obtained by pull-out tests in laboratory.The test results indicate that the dominant failure model of prestressed anchor cable under concentrated tension is debonding along the cable-grouting material interface.The paper abtains the elastic solution of stress distribution on two bond interfaces of embedment section via rational mechanical computation mode.The analyses demonstrate that the peak stress of bond interface between cable and grouting is located at the hole-top of anchorage hole,the stress distribution is highly uneven,which causes debonding of the cable-grouting material interface of hole-top first,the debonding interface transfers to the end of embedment section in progress and finally draw out the cable from the grouting.It should be attach great importance to the study results mentioned above in the design of anchorage engineering and revision of technical specification for prestressed anchor cables in the future.