The Use of an Innovative Mechanical Fastening Technology to Replace Failed Fixing Bolts and Extend the Useful Life of Anchored Steel Bulkheads

At an oil transfer terminal owned and operated by an international oil company, there is presently a bulkhead, most of which was constructed in 1971, that is approximately 853 m (2,800 ft) long with a design dredge elevation that varies between –11.9 and –6.1 m (–39 and –20 ft) MLWD (Mean Low Water Datum). The bulkhead is made of steel sheet piles secured by bolts to a double-channel, interior wale that is anchored via tie-rods to an upland, buried, steel sheet pile wall. The bulkhead is in fair to good condition after 29 years of service with one exception: the bolts that fasten the sheet piles to the wale (i.e., fixing bolts) are failing due to excessive corrosion. As a result, since 1996, sheet piles in several areas of the bulkhead have separated from the wale and deflected waterward (i.e., localized areas of bulkhead failure are occurring). Each time a failure occurs, it results in costly repairs and significant disruption to terminal operations. More failures are anticipated in the future unless measures are implemented to identify and replace deteriorated fixing bolts. This paper provides detailed coverage of the development, testing and use of an innovative and cost-effective mechanical fastener developed to replace failed fixing bolts without upland disturbance. Use of the new fastener can result in a significant reduction in the time and expense of replacing failed fixing bolts over traditional methods, such as excavating behind the bulkhead. Further, if used as part of a comprehensive maintenance program, the replacement mechanical fastener can prevent costly bulkhead failures and substantially extend the useful life of anchored, steel sheet pile bulkheads with interior wales, a commonly encountered bulkhead configuration.