SM490A鋼管樁斷裂破損原因分析

Failure Analysis of SM490A Steel Used For Pipe Pile

賴建霖(Chien-Lin Lai) ； 吳宗峯(Tseung-Feng Wu) ； 羅亦旋(I-Hsuang Lo)

《防蝕工程》 36卷4期 (2022/12) Pp. 23-29

https://doi.org/10.6376/JCCE.202212_36(4).0003

摘要

高雄港第三碼頭興建工程，使用SM490A鋼板，經彎曲加工後再銲接製成鋼管，鋼管以機具夾持後再進行打樁，為減少夾持機具對鋼管之損傷，鋼管內圈以銲接方式銲上一塊補強板，打樁過程發生一根鋼管樁打入海底，於重新拔起時頭端斷裂。本研究利用材質成分分析、顯微鏡觀察組織、硬度量測，再配合破斷面形貌觀察，進行破損肇因分析。研究結果顯示，鋼管樁破裂主因為銲道與鋼管連接處的不連續面導致應力集中，且應力集中處位於銲接熱影響區的硬脆組織區域，振動打樁過程中即產生裂紋，並於後續拔樁時發生斷裂。將銲道與管件連接處之不連續面研磨成較為平順之連接面，可減緩應力集中的程度，降低鋼管樁於打樁過程斷裂之機率。

關鍵字

銲接 ； 熱影響區 ； 應力集中

並列摘要

The construction project of Kaohsiung Port No. 3 Wharf used SM490A steel plates, which are bent and processed and then welded into steel pipes. The steel pipes are clamped by machines and then piled. In order to reduce the damage to the steel pipes by the clamping machines, a reinforcing plate was welded on the inner side of the steel pipes. During the piling process, a steel pipe is driven into the seabed, and the head is broken when it is pulled up again. In this study, chemical composition analysis, microstructure observation, hardness measurement, and fracture morphology observation were used to analyze the causes of failure. The results show that the fracture of the steel pipe pile is mainly due to the stress concentration caused by the discontinuous surface at the connection between the weld bead and the steel pipe. The stress concentration is located in heat affect zone (the hardest area of the weldment). Therefore, the cracks initiate during the vibratory piling, and fracture occur during subsequent pile extraction. Grinding the discontinuous surface at the connection between the weld bead and the pipe fitting into a relatively smooth surface can lower the stress concentration level and reduce the probability of the steel pipe pile breaking during the piling process.

並列關鍵字

Welding ； Heat Affected Zone ； Stress Concentration

參考文獻

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