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Piles are commonly used foundation structures. The installation process of piles is governed by dynamic processes which induce stress waves into the pile and the surrounding soil. Hence, the bearing capacity of the installed piles is influenced by the dynamic behavior and the resulting pile-soil interaction. To predict realistic bearing capacities, it is important to establish a thorough understanding of the underlying processes. Based on an understanding of both pile design and installation of offshore piles it is possible to identify the main influencing factors of dynamic load tests and to derive as well as to validate a new evaluation method for dynamic load tests. Another application that focuses on the dynamic pile behavior is the pile driving analysis. The impact of (unexpected) obstacles such as boulders in the ground represents a critical design consideration for pile driving. An approach to evaluate the pile behavior when impacting boulders during driving by applying one-dimensional wave theory is described. The example also emphasizes the limitations of using one-dimensional wave theory to evaluate the pile-soil interaction and provides an alternative outlook based on the proposed evaluation method for dynamic load tests.

Soil setup effect is a natural phenomenon where pile bearing capacity increases over time as a result of dissipation of excess pore water pressure as well as soil aging. Soil setup significantly contributes to the increase in shaft bearing capacity of prefabricated displacement piles installed in saturated clay. The past experiences indicate that shaft bearing capacity increases almost linearly with the logarithm of time elapsed after the pile initial drive, usually quantified using a dimensionless setup factor. The magnitude of setup factor is governed by pile geometry and type of surrounding soil. To quantify the setup rate potential, a minimum of two field measurements of the pile ultimate load are required. Whenever signal matching analyses are performed on pile dynamic load test results at end-of-drive and restrike data, the variations of setup effects along the pile shaft can be determined. The main objective of this paper is to evaluate the effects of over-consolidation ratio (OCR) on setup factor using pile dynamic load tests (DLT) at end of initial drive and restrike as well as static load tests (SLT). For this purpose, an elaborate field testing program was conducted at Bidboland II Gas Refinery site. The program consisted of DLT and SLT on the prestressed spun concrete piles that have been driven at different locations of the site having variations of OCR as a result of preloading under different surcharge pressures. Results indicate that shaft resistance has considerably increased over time at the study site. The setup factor is affected by the over-consolidation ratio in such a way that with increasing OCR, the setup potential has reduced. The findings of the study are useful in engineering applications of piling in clayey deposits in which the time constraints of construction does not allow performance of dynamic load tests at different time steps as well as estimating the setup factor at sites having over-consolidated soil.

Many precast driven piles have been constructed in soft soils of southwest Iran in Khuzestan Province in oil, gas, petrochemical and other industrial projects within the past 20 years. Estimating the adequate pile bearing capacity and drivable embedment depth of piles are always a major challenging task both during the design and construction phases. Clients have been promoted to carry out dynamic load test (DLT) and static load test (SLT) on both “test piles” and “construction piles” to optimize the pile design and improve the execution quality. Data sets of several projects with number of piles ranging from 5000 to 8000 in each project are compiled for comparison purposes of the ultimate load obtained from DLT with SLT tests. The study area geological stratification is mostly comprised of soft cohesive layers on top underlain with medium stiff to stiff strata. Soil setup potential is understood to be considerable in the region. During the pile testing program, it has been attempted to carry out DLT at the end of drive as well as restrike at different time intervals up until few weeks or months. Then correlations for soil setup are used to determine the parameters of the study site such as “A” and t0 of Skov and Denvor relation. The results have shown that the t0 is very variable in the region ranging from 0.1 day in highly permeable strata up to 1 day in pure cohesive strata with low permeability. The results also indicate that if the DLT tests are corrected for setup effects equivalent to the SLT time past from the initial drive, more accurate agreements could reach. During piling operation, as it may not be feasible to wait for sufficiently long time for the setup to occur, and usually DLT tests are carried out within few days from pile installation, the extrapolated capacities considering site specific setup effects are used in verifying the design capacities. Considerable savings are made through the explained procedure both in “construction cost” and “construction time” of the projects.

Tokyo International Cruise Terminal, a four-story passenger ship terminal, was constructed at the Tokyo Bay area in 2020. The terminal building is on the jacket-type pier foundation supported by large-diameter steel pipe piles (SPPs) having an outer diameter (Do) of 2 m. A very soft sediment exists below the seabed to a depth of about 35 m. The surface soft layer is underlain by a gravel layer of 4 m thick and a mudstone layer having SPT N-values greater than 50. In order to estimate an appropriate embedment length of SPP in the gravel layer or the mudstone layer, rapid load tests (RLTs) were carried out on two SPPs having a length of 57 m (Pile 1) or 62 m (Pile 2). For both SPPs, double crossed steel ribs (#-shaped ribs) were welded inside the piles along the bottom 5 m section. Both piles were instrumented with strain gages at 8 levels to obtain axial forces during RLTs. High plugging was observed in both piles

The author evaluated H-pile load test data from three (3) sources: 1) Florida database of 641 H-piles from public bridges with Dynamic Load Test (DLT), 2) FHWA database of 23 H-piles having both DLT and Static Load Test (SLT), and 3) a private sector project with detailed DLT and SLT results. The need for this study originated from occasional very large divergence between DLT results and static analyses results of H-piles in several projects. Upon detailed evaluations it is concluded that the observed large divergence is not due to correlations discrepancy, but rather the invalidity of the DLT results for certain H-piles, especially for 1) long H-piles with penetration depth exceeding 30 m, the piles may behave as plugged in the static condition, but as unplugged during dynamic loading event; 2) short H-piles, the conventional lumped CASE damping factor in conventional range should not be relied on for these piles.

Three bidirectional static load tests (BDSLT) were executed on bored concrete piles, as part of the permanent foundations for two buildings sites located at the Sabana, San Jose, Costa Rica, separated at a relatively short distance of about 1 km. Unit skin friction values obtained for both sites, principally for the “Lahar” layer show that in general, friction pile capacity from the tests is higher than anticipated per static calculations from soil borings geotechnical parameters correlations. Results from the tests were also compared with dynamic load tests (DLT) executed at other two sites in the surrounding area, and with a Finite Element (FE) Analysis that model soil-pile interaction for one of the projects. On the other side, some construction issues were detected on one of the sites, which negatively affected the end bearing capacity, but being that pile friction was higher than anticipated, the required overall pile capacity was accomplished. The BDSLTs results of these tests help to better understand the geotechnical behavior of the soil layers in the Sabana. Moreover, they also show that is possible to optimize the design and construction of other bored pile supported buildings and structures on the zone.