Pile Load Tests in Dense Sand: Planning, Instrumentation, and Results

ABSTRACT Two driven, 18-m (59-ft) long, 0.61-m (24-in.) diameter steel pipe piles were tested in a very dense Sam in the Rasp Tan jib area on the east coast of Saudi Arabia. The piles were instrumented along their length with strain gages am tell-tales for measurement of pile stresses am displacements during testing. Pile top stresses am acceleration were also measure during driving. The first pile was tested in tension to the maximum load that could be applied with the testing frame. Cyclic tension and creep loading tests were then conducted. The second pile was tested first in compression to the maximum available load fan the test frame, and then tested to failure in tension; Maximum applied loads ranged Fran 12.7 MN (2854 kips) in tension to 16.8 MN (3775 kips) in compression. The ratio of maximum applied loads during the tests to the capacity Imputed by the American Petroleum Institute method1 ranges from about 3.5 (in compression) to 11.5 (in tension). INTRODUCTION Considerable difficulty has been experienced in driving 0.6 to 1.2-m (24 to 48-in.) diameter steel pipe piles to 20 to 40-m (65 to 130... ft) penetrations in the Arabian Gulf. Layers of very dense or cemented Sam, and rock encumbered during pile driving have result: I in frequent pile refusal, even where pile driving hammers with rated energies of 407 KN-m (300,000 ft-lbs) were used. Costly am time-consuming remedial construction, consisting of drilling, jetting, retrieving, and/or installing grout plugs or insert piles have often been required. In addition, piles were occasionally damaged during driving. Base: I on accumulated experience Fran soil borings, pile installations, and limited pile load test data in the Arabian Gulf, it became apparent that the methx1s that were used for computing pile capacities may have 'been germy conservative. These methx1s had been developed primarily in the Gulf of Mexico, and were appropriate for soils that were significantly different Fran the soils found in the Arabian Gulf. Full-scale pile load tests were, therefore, needed to increase understanding of the behavior of the Arabian Gulf soils. Arabian Gulf soils are highly variable over relatively short lateral am vertical distances. The geological history of the area explains most of the variability and the occurrence of strong soils am rock. During the worldwide lowering of sea level cause by the Pleistocene glacial advances, the entire Gulf was sub-aerially exposed. Tributary rivers developed through the exposed Tertiary carbonate rock and carried sediment Fran the inland Arabian Shield. The downward cutting of river channels created an uneven erosion surface throughout the Gulf. These channels were later filled as the sea level rose.