PILE DAMAGE EVALUATION METHOD

To provide a pile damage evaluation method which can accurately evaluate pile damage.SOLUTION: A pile damage evaluation method includes: a step of acquiring time from generation of an elastic wave by striking a head part of a pile that has a known length and is to be evaluated to propagation of the elastic wave through the pile, reflecting the elastic wave on the tip of the pile, and propagation of the elastic wave to the head part; a step of acquiring an elastic wave propagation speed measurement value in the underground of the pile from the length L of the pile and the time; a step of acquiring an elastic wave propagation speed measurement value in the air of the pile; a step of acquiring an elastic wave propagation speed calculation value V' in the underground of the pile with no damage from the elastic wave propagation speed measurement value in the air of the pile, in consideration of an influence of the ground in the periphery of the pile; comparing the elastic wave propagation speed measurement value in the underground of the pile with the elastic wave propagation speed calculation value V' in the underground of the pile, and determining a reduction ratio η of the elastic wave propagation speed by the damage of the pile; and a step of determining magnitude of the damage of the pile from a relation between magnitude of damage obtained by previous testing of a test pile having the same material as the pile and the reduction ratio η of the elastic wave propagation speed.SELECTED DRAWING: Figure 6 【課題】的確に杭の損傷を評価することが可能となる杭の損傷評価方法を提供する。【解決手段】既知の長さを持つ評価対象の杭の頭部をたたいて弾性波を発生させてから、杭を伝播し杭の先端部で反射し、頭部に伝播するまでの時間を取得するステップと、杭の長さＬと時間から杭の地中での弾性波伝播速度計測値を取得するステップと、杭の気中での弾性波伝播速度計測値を取得するステップと、杭の周囲地盤の影響を考慮して、杭の気中での弾性波伝播速度計測値から、損傷の無い杭の地中での弾性波伝播速度計算値V'を取得するステップと、杭の地中での弾性波伝播速度計測値と杭の地中での弾性波伝播速度計算値V'とを比較して杭の損傷による弾性波伝播速度の低下率ηを求めるステップと、杭と同じ材質の試験杭に対して予め試験して求めた損傷の大きさと弾性波伝播速度の低下率ηとの関係から杭の損傷の大きさを求めるステップと、を有する。【選択図】図６