基於振動之橋梁基礎檢測案例研究

CASE STUDY OF VIBRATION-BASED FOUNDATION INSPECTION FOR BRIDGES

柯永彥(Yung-Yen Ko) ； 張為光(Wei-Kuang Chang)

《中國土木水利工程學刊》 33卷2期 (2021/04) Pp. 163-174

https://doi.org/10.6652/JoCICHE.202104_33(2).0008

摘要

為了對不易到達或目視之跨河橋梁基礎進行檢測，本研究量測並分析橋梁上部結構之振動反應特性，藉此展現橋墩基礎之狀態。文中將呈現兩個現地試驗案例，包括沉箱基礎長期遭沖刷而嚴重裸露之北部某橋梁，與部分群樁基礎曾進行增樁補強之南部某橋梁，兩者均於多個橋墩對應之橋面位置進行環境微振同步量測記錄。結果顯示，不論由振動頻譜判別之顯著頻率，或由橋梁單元之實驗模態分析結果，均可反映因基礎因沖刷裸露造成之弱化與因增樁造成之強化等效應，驗證基於振動之橋梁基礎檢測法具實務可行性。

關鍵字

橋梁基礎檢測 ； 振動量測 ； 沖刷 ； 基礎補強

並列摘要

For the inspection of the foundations of river-crossing bridges which are not accessible or not visible, this study aims to exhibit the foundation state by measuring and characterizing the vibration response of superstructures. Two in-situ cases are presented, including a bridge in Northern Taiwan of which the caisson foundations had been long suffered scour and were thus severely exposed, and the other in Southern Taiwan of which some group-pile foundations were retrofitted by adding piles. For both cases, the ambient vibration on the deck was synchronously measured and recorded at multiple piers. Results showed that either the weakening of the foundation due to scour or the strengthening because of additional piles can be revealed by both the predominant frequency identified by the vibration spectrum and the experimental modal analysis of a bridge unit. Thus, the vibration-based foundation inspection was verified to be practically feasible.

並列關鍵字

bridge foundation inspection ； vibration measurement ； scour ； foundation retrofit