基隆港鋼板椿結構物腐蝕調查研究

Corrosion Studies of Steel Sheet Pile Structures in Keelung Harbor

港灣碼頭鋼板椿結構物容易發生腐蝕，而國內尚未有腐蝕調查之經驗，本文係以基隆港七座鋼板椿碼頭所進行的初步腐蝕調查個案作為探討之對象，調查結果發現曾進行過防蝕措施者較未作防蝕者之腐蝕量為輕；而鋼板樁凸面之腐蝕速率較凹面為高，而側面側則為最低。以所處海洋環境位置考慮，則以潮汐帶（低潮位上方0.35m）為最高，水線上（低潮下－0.05m）次之，海中區（低潮低下3公尺）為最低。而在同一水域腐蝕型態之變化性很大，且發現有些裂縫，孔洞及穿孔出現。腐蝕速率超過設計規範0.2mm／yr值者也很多。建議各港務局應對全港區之鋼板椿作一詳細調查，如此可充份地瞭解該港區海域下鋼板椿腐蝕特性，可建立適用腐蝕速率預報公式及採取適當的補修與設計之策略。

The steel sheet piles used in harbor wharf structures are easily corroded. The purpose of this study is to understand the corrosion situation of steel sheet pile structures in the harbor wharf and to examine the effectivenss of corrosion protection. There are seven wharves with steel sheet piles in Keelung harbor were examined. From the data obtained, it is found that the corrosion for the cathodically protected structures is less than that for unprotected structures. At each water level, the corrosion rates of the convex sheet piles are higher than those of the concave sheet piles. One per 30 sheet piles was chosen for each wharf and the thicknesses of steel sheet piles were measured at 3 water levels of LWL+0.35m (in the tidal zone); LWL－0.05M (just below low water level) and LWL－3.00m (in the submerged zone) etc. The maximum corrosion rate is in the tidal zone where is just below mean low water level, and the minimum one is in the submerged zone. There appeared many different corrosion patterns in the some level. Furthermore, also some of cracking, pitting and penetration are found in the strcutures, The corrosion rates of all steel sheet piles are higher than that of design guide (0.2mm/yr). It is recommended that the detailed corrosion survey of harbor steel structures should be taken in each harbor, in order to have a full understanding of the performance and corrosion characteristics of the steel sheet pile structure under different marine environments; and to get the suitable estimated formula for corrosion rate Thus, the proper corrosion protection methods and maintenance treatments ect. for engineering usage can be established.