PIARC Prize "Best Innovation" - Efficient Safety Assessment of Expressway Slope Reinforced by Ground Anchors based on Residual Tensile Load Evaluated by Vibration Method

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Ground Anchoring is one of the popular methods for maintaining the stability of expressway slope. To maintain the stabilizing function of the anchors, it is necessary that the anchors are not corroded and the residual tensile load is maintained within the expected range. The soundness of anchor is evaluated based on the Guideline for the evaluation of residual tensile load [1], [2] (table 1). Periodic inspections of anchors are important to ensure the slope stability. Expressway companies have carried out the mandatory inspections including the confirmation of the residual tensile load of 5% of total anchors or at least 5 anchors for each anchored slope every five years in accordance with the maintenance manual [3] and survey manual [4].