Abstract：Based on field testing results and numerical simulation of prestressed anchor cable of tunnel anchorage system of suspension bridge，the ultimate anti-pulling capacity and failure mode affected by anchor-length，free- length，grouting quality and interface mode between grout-cable and rock mass are analyzed. Stress distribution modality in rock mass and root effect are also introduced. And the concept of safety storage coefficient is put forward. It indicates that the increase of ultimate anti-pulling capacity increase principally depends on synthetical functions of the variables mentioned above. Free-length has key effect on effectively transferring and dispersing stress to wall rock. The failure mode of anchor cable is controlled by free and anchor length. The contribution value and occasion of anchor cable are determined by its free-length and initial stress.
