Buckling of load Unsupported Timber Piles

The results of a pile loading test made on a group of four long, unsupported, timber piles in order to determine their ultimate buckling capacity are presented. The test results confirmed that the ultimate bearing capacity of the long timber wharf piles was governed by the buckling capacity of the unsupported section of the pile. The buckling capacity of the long piles, acted on by an eccentric vertical load, can be determined theoretically with satisfactory accuracy, using the appropriate form of the secant equation. Appreciable lateral support was provided to the embedded part of the timber piles by the soft foundation soils that exist at the site. The computed depth below the mud line to the apparent point of fixity ranged from 6 ft to 11 ft. Conventional practice for soft foundation soils is to assume fixity at 10 ft depth. The test results confirm this practice to be reasonable.