Full-Scale Testing and Foundation Design: Honoring Bengt H. Fellenius

Geotechnical engineering in Sweden has a long tradition due to the presence of soft and sensitive clay deposits along lake and sea shores, where most settlements were established. As the country increasingly took on the difficult tasks of constructing harbors, canals, and foundations for roads and railways, novel foundation concepts had to be developed.The establishing of an interdisciplinary "Geotechnical Commission" in 1914 consisting of geologists and civil engineers with the task to study landslides and slope failures laid the foundation for modern geotechnical field and laboratory testing methods and began the key role of geotechnical engineering in Swedish civil engineering. A very important aspect is the spirit of close cooperation between practitioners, engineers, and scientists, manifested in the Swedish Geotechnical Institute and the Swedish Pile Commission. The Swedish geotechnical practice has a long history of important accomplishments by individual engineers. A few notable contributions to geotechnical engineering by Swedish engineers and scientists from the early stages of civil engineering around 1600 until about 1960 are listed in the paper. The contributions encompass mining, canals, railways, harbors, foundations, earth retaining structures, dams, slope stability, and information systems.

Area subsidence, and settlement and deformation in precast concrete piles supporting a three-story building were monitored over a three-year period. Soil profile was 3 m clay crust followed by 13 m of normally consolidated soft clay above sand. Anticipated groundwater table lowering was monitored in three piezometers (open pipes) along with measurements of settlement and shortening of four piles under the building, and settlement of ground surface and building. The results showed that incorporating water infiltration was successful in preventing lowering of the groundwater table. The settlement of the ground surface was consequently negligible, about 20 mm, and the pile deformation was small. The load applied to the piles from the building caused the piles and building to settle about 2 mm. During the following three years, a further 1 mm settlement was observed of which the settlement of the pile toe was about 0.2 mm. The pile shortening corresponded to 500 microstrain deformation of the piles and was one fifth due to creep of the pile material and to four fifths due to negative skin friction. Despite the small soil settlement, drag load due to accumulated negative skin friction along the piles was estimated to be about 200 KN.

Using Osterberg cells (O-cells), a load test was conducted on a large bored test pile constructed in 2006 for the Golden Ears Bridge project, east of Vancouver, British Columbia. Unique aspects of the test included depth and diameter of shaft, subsurface conditions, excavation technique, weight and length of rebar cage sections, cleanout of excavation, and positioning of the two O-cells. Using a special spherical grab, a 2.5-m-diameter shaft was excavated to 74.5 m depth using polymer slurry drilling mud. Presence of the O-cells assemblies hampered final cleanout of the excavation, and shaft integrity below the lower O-cell was affected by the presence of chunks of stiff clay, probably scraped from shaft sidewall during installation of the reinforcing cage. Despite this, testing of the shaft mobilized a combined toe and side shear resistance of over 62 MN and demonstrated that, for a top loading of 50 MN, the test pile would displace only 30 mm. From this, it was also concluded that noticeable creep of the shaft would not begin until top loading exceeded 30.5 MN. The test results allowed reducing the length of the main bridge piles and improved confidence in the foundation design.

To validate the foundation design for the main piers for Pitt River Bridge Design-Build (DB) project, a conventional, head-down, static pile loading test was carried out using production piles for both the test and reaction piles to minimize costs. The piles comprised of an 1824 mm diameter, open-toe, steel pipe driven into very dense Pleistocene deposits (glacial till or drift and inter-glacial sediments) at approximately 100 m depth. The loading test was completed successfully in December 2007 to a load of 45 MN by the design-build contractor, Peter Kiewit Sons. Design of the piles was based on information provided by the owner to the DB proponents and included results of test holes and static pile loading tests conducted in the 1970s on 36 and 55 m long, open toe steel pipe piles, CPT and SCPT profiling conducted in the 1990s and mid-2000s, and dynamic load tests (DLTs) conducted on an 100 m long, 1067 mm diameter, open toe indicator pile installed in 2005. Test pile installation records and Pile Driving Analysis (PDA) records and signal matching analyses for the 2005 test pile were used to calibrate the design and confirm pile installation requirements. Supplementary test holes, and CPTs and SCPTs were conducted to over 100 m depth to calibrate pile resistance, particularly pile toe resistance. DLTs were also conducted on several of the production piles to validate the design. This paper presents key aspects of each of the points mentioned above.

A 1.5 x 2.8 m, 44.5 m deep barrette was constructed in weathered sedimentary rock of the Jurong formation in Singapore with an O-cell assembly of two O-cells installed at 33.5 m depth, 11 m above the barrette toe, chosen presuming that resistance above and below the cell level would balance. When the O-cell test was performed, a proof test at the end of the construction work, the shaft resistance for the section above the O-cell level was surprisingly low; the shaft failed at a load of only about 3 MN. In a re-test, at the maximum O-cell load of 12.5 MN, the upward movement exceeded 100 mm. The barrette was then tested in a conventional head-down test, which first (second test stage) was with the O-cell vented to validate the results of the O-cell test. In a third stage, the opening between the O-cell plates was grouted in order to transfer load across the O-cell level to mobilize the shaft resistance along the lower section of the barrette and the toe resistance. The results of Stage 1 O-cell upward test and Stage 2 head-down test on the pile with free-draining O-cell agreed well, as did the Stage 1 equivalent head-down test and Stage 3 head-down test. Stage 3 test confirmed a 12 MN working load, downgraded from the original 33 MN value. The test results are discussed and referenced to a numerical (FEM) analysis.

Full-scale static loading is a widely accepted test method for authoritative assessment of deep foundations. Testing is typically performed once and the result is considered the definitive answer regarding the pile's load bearing capacity. However, there are technical and operational reasons that may cause misleading results. This paper presents a case where a large concrete pile was subjected to two full-scale static, and several dynamic loading tests. The pile was initially driven to a predetermined depth based on conventional geotechnical analyses, and its capacity was confirmed by dynamic testing. However, the static loading test indicated a pile capacity well below the anticipated value. Dynamic testing performed during restrike one day following the static test indicated a capacity close to that of the static load test. The pile was subsequently driven 4.4 m deeper until dynamic testing indicated it had achieved the required capacity. A second static loading test was performed that confirmed the required capacity. A review of the construction records revealed that in preparation for the static load test, the reaction steel H-piles were vibrated to below the test pile toe following the installation of the test pile. Analysis of the dynamic and static testing results confirmed that the installation of the reaction piles adversely affected the bearing layer resulting in reduction of pile capacity and the failed original static test.Utilization of dynamic pile testing and geotechnical analysis made it possible to uncover the flaw in the static loading test setup procedure and, thus, the unreliability of the original static load test result. This case study demonstrates that static load tests can sometimes be misleading, and supplemental dynamic pile testing is a valuable tool to establish reliability and ascertain fidelity of results.

Augered cast-in-place piles are installed by the excavation of the soil by rotation of a continuously flighted auger into the ground and then placement of a fluid cement grout into the evacuated volume as the auger is extracted. The soil conditions immediately after excavation for augered cast-in-place piles will be related to the in situ soil conditions, the auger specifications, and the rates of penetration and auger rotation. Intuitively, the potential for soil removal will increase proportional to the number of auger rotations; however, the soil transport mechanism involved is complex. To evaluate the effect of augering on the axial behavior of full-scale augered cast-in-place piles, four piles were installed with varying auger rotations and then load tested in axial compression. The soil conditions were primarily sand above the water table. The results of cone penetration testing indicate that the number of auger rotations did not significantly influence the cone resistance in the sand above the water table. Limited data suggest that some loosening occurs in the sand below the water table. The results of the loading tests indicate that the geotechnical resistance - and notably the shaft resistance -is not sensitive to the number of auger rotations for the study conditions.

This paper demonstrates that reducing uncertainties in pile design and construction has the potential to greatly reduce foundation money and time costs for non-redundant driven and drilled pile foundations. It describes the statistics-guided Testing and Remediation Observational Method (TROM). This method permits reducing the factor of safety (FOS) in deterministic design, or increasing the . resistance factor in load resistance factor design (LRFD), while maintaining a target reliability for all piles by remediating as needed. Three example case histories demonstrate the method and the advantages of testing every pile.

The Port Mann Bridge on Highway 1 in Metro Vancouver links the cities of Surrey and Coquitlam in British Columbia, Canada. A new 10-lane 2.02 km long cable-stayed bridge is being constructed over the Fraser River to replace the existing 5-lane bridge. Twelve of the twenty-five bridge piers will be supported on driven steel pipe piles. As part of the foundation design approach, a full-scale instrumented static pile load test was performed along with dynamic pile testing. The test and reaction piles consist of 75 m long, 1,830 mm diameter by 25 mm thick, open-ended steel pipe piles driven into glacially overridden soil using an APE D-180-42 diesel hammer. A custom-built static load frame and hydraulic jacking system provided incremental compressive loads up to 53 MN on the test pile. Following the compression test, an uplift test to 29 MN was performed. The pile was restruck with a Menck MHU 500T hydraulic hammer 9 days after the uplift test. Evaluation of the pile resistance distribution included impacts of residual load and pile plugging. Pile performance during the static load test indicated that approximately 36 MN was carried in side resistance and approximately 17 MN was provided in base resistance. The static pile load test and dynamic testing of selected production piles enabled the use of increased resistance factors for final design, thereby reducing the number of piles to 255, a reduction of approximately 30 percent.

This case study outlines an installation and loading test programme conducted for foundation design at an oil sands mine in Alberta, Canada. Design was for approximately 10,000 driven steel piles of various sizes founded in dense glacial deposits of sand and silty sand. Included are results from pre-construction loading tests (9 static axial tests, 56 high strain dynamic test measurements) and construction QA/QC (7 static axial tests, 5% of piles with high strain dynamic test measurements). Only 5% of piles had damage when pile shoes were used versus 46% without shoes. When piles were driven through frost without pre-drill 83% were damaged. Design curves using a modified API method provided a capacity ratio of 1.0 for dynamic tests during pre-construction versus a range of 0.4 to 0.9 during construction. It was found that at a remote site there is more value-added increasing the installation and loading test programme scope versus the subsurface investigation. Also, when using an API design approach, extrapolating to diameters and lengths other than those tested led to skewed results; the general trend was over-conservative design for smaller diameter piles and under-conservative design for larger diameter piles as relative depth increased.

This paper shows the behavior of two mat foundations built on soft clay, representing full size structures for low income houses. The lack of habitation in Brazil is tremendous right now and any contribution to a better geotechnical solution for this problem is more than welcome. Very often, areas used for housing developments have clay of high compressibilityin the subsoil profile with settlement, becoming a major concern. Two full size mat slabs (4 x 4 m each) were built directly on the problematic soils, the Belém River Valley in Curitiba, Southern Brazil. Geologically, the subsoil profile is defined by about 4 meters of soft organic clay, basically OH (USCS) deposited by the river over more competent silty clay material, from the local Guabirotuba Formation. One of the slabs was partly supported by short sand columns attempting to give a better idea about how different the behavior of the foundation would be over time, considering a reasonable surcharge representing the real house loads. A careful topographic settlement monitoring program was then carried out for a few months, allowing for some conclusions to be drawn and later applied to other similar projects. The main finding was the substantially smaller vertical movements of the slab on sand columns compared to the no sand columns, with a 1:2 approximate ratio, based on settlement. Only small settlement readings were obtained (about a few millimeter). Examples of some applications of what was learned from the research are also mentioned, showing the importance of using experimental data in engineering practice.

Two recent bridge projects in British Columbia highlight the importance of having well-instrumented pile loading tests as part of pile foundation design. First case is the 1.5 km long, five-lane W.R. Bennett Bridge in the challenging Okanagan Lake soil profile with soft and loose to medium dense silts and silty sands to depths over 100 m. Five 610-mm diameter open- and closed-toe test piles were driven to 45 m depth. Pile dynamics tests were performed for all five test piles and a static loading test was carried out on the center pile, driven closed-toe. The importance of considering residual load in the test interpretation is illustrated. Second case is the 2.6 km long (main bridge and approaches) six-lane, cable-stayed Golden Ears Bridge over the Fraser River delta. Soils consisted of thick, potentially liquefiable sands, overlying near-normally consolidated soft to stiff clayey silts and silty clays to over 120 m depth. The south approach and main span piers are founded on 2.5 m diameter bored piles of up to 85 m length. Four loading tests were carried out for this project. One of the tests, a 74 m deep 2.5 m diameter pile loaded with bi-directional O-cells is described and the test results, their interpretation, and general foundation design methods and considerations are presented.

Small diameter pipe piles called pin-piles are often used in the Seattle area for underpinning small structures, especially at sites where access is difficult or constrained. Pin-piles are most commonly 60 mm [50 mm nominal] diameter and 89 mm [75 mm nominal] schedule 80 black iron pipe driven with a 41 kg jack hammer or a 68 kg Rhino hammer. In the dense glacial soils often found in the Seattle area, piles are frequently damaged during driving to the specified one minute driving criterion. Furthermore, only very small if any settlement is observed under working loads, and even load tests carried out to twice the allowable load often show settlements of only a very few millimeters. The paper begins with a brief history of the development of pin-piles and the basis for driving criterion and the limitations on allowable loads currently imposed by municipalities in the Seattle area. Then the results of three research projects carried out at the University of Washington in cooperation with local consultants and contractors are summarized. It was found from both static load tests and limited dynamic testing that ultimate load capacity is often 3.5 to 5 times greater than maximum loads allowable without a static load test. Finally, we show the results of thirteen production static load tests on 152 mm diameter pin-piles loaded to 180 kN. The deflections were very small and the results tend to support our contention that the presently allowable load capacities are conservative. Recommendations for future research and local foundation design and construction practice are given.

In France, the standard for the design of deep foundations is being updated with new requirements on the effect of cyclic loading. As no design method exists to take into account this type of loading, a research project was launched (SOLCYP). The field test part of this project consists in an experimental program with compression and tension full-scale pile test is undertaken to study the behaviour of piles under cyclic loading. The main feature of the field tests will consist in measuring the distribution of load (shaft and toe resistances) along the pile during static and cyclic tests. To achieve this scheme, the use of the LCPC (French Public Works Research Laboratory) removable extensometer is required. It was tested for cyclic tests for a frequency up to 1 Hz. One of the main objectives is to point out pile bearing capacity degradation and cumulative displacement due to repetitive service loads. This paper summarizes preliminary full scale compression tests achieved in 2008. It shows the good reliability of the monitoring method to get the distribution of load along the pile during cyclic loading from 0.1 to 1 Hz frequencies load controlled tests. From the measurements of the load segments, the load was fairly distributed along the pile. As far as cumulative displacement is concerned, the pile response depends on the number of cycles, the load amplitude and loading history.

Site investigation, geotechnical analyses, and pile testing were performed in 1990-91 for the design of pile foundation for towers and anchors on a telecommunications project in Morocco. The soil profile consisted of estuarian and lagoonal deposits with a normally-consolidated clay deposit overlying overconsolidated clay (hard basal clay). An estuarine sand deposit of variable thickness and density is located between the clay and basal clay, in places sandwiched within the clay. Consolidation properties of the clay were back-calculated from the records of settlement under an extensive berm constructed earlier at the site. Analyses of pile compression and uplift capacity were performed by several methods. Calculations were also made of deflections and bending moments induced in inclined piles by continuing ground settlement. In most cases, the piles achieved the required tension and compression capacity in the sand and basal clay. However, attention needed to be paid to areas where the sand was relatively thin and underlain by clay. Test piles driven to the calculated depths were tested in compression and tension. The results of the pile testing programme indicated that pile analysis methods employed at the time provided a reliable prediction of the actual pile capacities, even under fairly complex soil conditions.

While it is common practice to monitor pile installation for offshore platforms in the hydrocarbon industry, the installation of foundation structures for offshore wind turbines is a new challenge. Wind Turbines to be installed in the German sector of the North Sea are mostly built on pile foundations. Both monopile as well as multiple pile - mainly three pile (tripile) - solutions are designed. As these piles have to resist high lateral loading, they must be embedded in strong competent soil layers. Open-end steel piles of large diameters are generally used and installed by impact driving. In general, hard driving conditions exist. It will be shown that the monitoring of the driving process by the Pile Driving Analyzer is not only important for the assessment of hammer performance and stresses in the pile or axial soil resistance, but also for lateral resistance. The assessment of the cyclic stability of the foundation requires an accurate prediction of the static capacity, which can be realised by dynamic pile tests. A proposal is given for the derivation of approximate p-y-curves for lateral loading directly from the solutions of CAPWAP model parameters.

The Bechara Industrial Park is located at San Juan Harbor in Puerto Rico (PR). The project is a flood control project for the Army Corps of Engineers with many components including the reconstruction of a berthing area using steel H-piles with allowable design load of 712 kN (160 kips). Static load test and dynamic testing were performed in the field on the same H-pile to verify that the soils can provide the required resistance with appropriate safety factors. Results of the static and dynamic testing indicated that the subsurface soils could not support the 712 kN (160 kips) design load with a safety factor of 2.0, and that the allowable design load should be reduced to 534 kN (120 kips). The static and dynamic test results were in general agreement with a difference of about 15%. In addition to the initial static and dynamic testing, dynamic testing was also performed on three other piles at different locations within the berthing area to verify that the reduced 534 kN (120 kips) design load can be accomplished. Results of the additional dynamic testing indicated that the piles can support the reduced 534 kN (120 kips) design load with a safety factor of about 2.0.

This paper describes a case history where penetration resistance of closed-end pipe piles in sand decreased with time. Pore pressure measurements from cone penetration tests (CPTu) suggests that the sand exhibited dilative behavior during the test, and the dilative soil behavior may have contributed to a temporary increase in penetration resistance during initial driving. A lower penetration resistance observed during re-strike was attributed to re-equilibrium of hydrostatic pressure. Static pile capacity analysis and dynamic pile driving analysis with PDA data indicate that pore pressure measured during CPTu is an appropriate tool for predicting pile relaxation.

The confluence of Interstate Highways I-94, I-43, and I-794 immediately southwest of downtown Milwaukee, Wisconsin, comprises the Marquette Interchange. The interchange covers a large area with highly variable soil conditions. A design-phase test program consisting of 88 test piles was undertaken to quantify both the time rate and magnitude of soil set-up. The test program included 51 indicator piles, 6 axial compression load test piles, 7 companion piles, and 24 reaction piles. Multiple restrike dynamic tests were performed with the last restrike typically conducted between 27 and 56 days after initial driving. Significant increases in shaft resistance occurred, with the poorest soil conditions exhibiting nearly a five-fold increase. Based on the test program results, 324 mm, 356 mm, and 406 mm O.D., closed-end pipe piles with maximum design loads of 1,334, 1,779, and 2,224 kN, respectively were used for the interchange foundations. These high-capacity pipe pile foundations were chosen because of reduced substructure size, reduced utility impact, and the associated cost savings provided by high-capacity foundation units. During interchange reconstruction, the construction schedule could not accommodate long-term restrikes. Therefore, a select number of test piles were dynamically tested during installation and during a short-term restrike at each of the 261 substructure locations. The capacity at the end of driving and the short-term set-up information was compared to the soil set-up magnitude and time rate of set-up quantified in the design-phase test program, and was used to develop pile installation criteria for the cost-effective, high-capacity pile foundations. Depth-variable driving criteria were used which incorporated the reduced end of driving capacity required with increasing pile penetration depth due to the increased soil set-up that occurred with deeper pile penetration depths.

Pile load tests were conducted on cast-in-place concrete piles founded in oil sand at three industrial plant sites located north of Fort McMurray, Alberta, Canada. The tests included static (top-down) tests with applied vertical loads of up to 10 MN, single cell and multi cell Osterberg Cells (O-cell) with applied loads of up to 22 MN, and Statnamic tests with loads of up to 16 MN. In addition, a creep test was held for 16 days on a static load test pile and a 21 day creep test was performed on an O-cell test, to assess creep characteristic of piles in oil sand. All piles were instrumented with load cells, embedded vibrating wire strain gauges, and in the case of the Statnamic tests, with accelerometers. The results of the pile load test programs indicated that straight shaft piles founded in oil sand are capable of sustaining high capacities due mainly to the high shaft friction in the oil sand at small deflections. This paper describes the installation and instrumentation of the piles, presents the test results and compares these to historical design values.

A series of tall apartment buildings was planned to be built on reclaimed ground over a thick deltaic deposit near-shore deposit outside City of Pusan in South Korea. The soil profile consisted of approximately 30 to 50 m of soft clay, silt, and sand on sandy gravel extending to bedrock at about 100 m depth. The deep foundation system normally used in Korea consists of steel pipe piles driven to significant toe bearing in dense soils or on bedrock. Because of the anticipated significant costs of this solution, a more economical alternative foundation system was essential, and the alternative of the PHC pile, a pretensioned spun high strength concrete pile, was proposed. To evaluate the feasibility of a PHC pile alternative, a comprehensive test programme was carried out, encompassing dynamic tests, long-term monitoring of negative skin friction, laboratory pilot tests, static loading tests on instrumented test piles, and settlement analysis. The analysis of the test data required study of strain effects from hydration and swelling of concrete, and of development of residual load before static testing, as well as of distribution of resistance along the pile due to applied load, and development of negative skin friction from settling soil and resulting drag load. Reliable estimation of pile group settlement was a key issue. Five methods for calculation of pile group settlement were compared and applied to the actual foundation layouts, of which one, the Unified Design Method, could include the effect of ongoing consolidating of the soft, compressible clay layer, interaction of adjacent foundations, and factual distribution of pile shaft resistance.

Steel piles of 1,219 and 1,016 mm diameter were driven open end in 16 to 20 m of water, to 36 to 44 m depth in marine soils of variable, but generally silty sand composition. The 308 piles support marine structures requiring maximum compression and tension service loads of 5,702 kN and 2,650 kN. The piles drove easily without soil plug development and driving resistances did not mirror the SPT profiles. Dynamic tests and CAPWAP analyses indicated soil set-up was essential to achieve pile capacities, but no clear trend emerged regarding required set-up duration. A pile subjected to static tension and dynamic compression tests indicated the static tension resistance was equivalent to 72 % of the dynamic shaft resistance and to K = 0.5. A static compression test on an unplugged pile indicated the average external/internal unit shaft resistance was 75 % of the unit tension resistance and about 50 % of the API predicted unit shaft resistance. External and internal friction was not equal and was grossly overestimated by the API method. Static and dynamic tests on another test pile indicated plugging had developed, as at this location internal shaft resistance was greater than toe end bearing.

This paper presents load transfer curves interpreted from a static load test performed on a large-diameter pipe pile in silty soils. In large-diameter driven piles and drilled shafts, appreciable movement is needed to mobilize toe resistance and thus settlement may control the design. Advanced load transfer methods require the prediction of the load transfer behavior along the shaft (i.e. t-z curve) and beneath the toe (i.e. q-z curve) of the pile. A number of generic load transfer curves for sand and clay are reported in the literature but limited information is available for large diameter piles and intermediate soils such as silt. This study develops t-z and q-z curves for silty soils from the analysis of a static loading test performed on an 1.8-meter diameter pipe pile in Rhode Island. The t-z curves from the test pile showed a softer load-movement response in comparison to those from slender piles in the literature. The results suggest that use of existing empirical t-z curves developed from slender piles in sands could lead to inaccurate load transfer analyses in large-diameter piles in silty soils.

Micropiles were used to support air quality control structures and equipment at a Southeast U.S. electric power plant in areas where construction equipment access for other types of deep foundations was very limited. The plant is located within the Piedmont physiographic province. The subsurface profile consists of upper medium dense silty and clayey sands, underlain by partially weathered rock (PWR), of varying thickness. The PWR is underlain by Gneiss bedrock with a relatively reduced degree of weathering, grading to a relatively unweathered rock. Due to the varying thickness of the PWR, the first Phase of the project included installation of two verification test piles to evaluate the contribution of PWR to pile capacity. Both test piles were installed with a partial length casing to stabilize the hole within the top portion of the sandy soils.The results of these tests indicated that PWR with sufficient thickness could be used as a load bearing stratum for micropile design; and that the surface casing could be used only as a means to stabilize the top of the drill hole. By using the PWR layer as a load bearing stratum and installing only partial length casing, the project team was able to considerably reduce the Phase 1 installation costs. However, due to variable subsurface conditions encountered during production, it was difficult to ascertain the depth to which the casing should be extended to stabilize the hole. Hence, a decision was made to install full-length casing for a Phase 2 test pile and subsequent production piles. The results of the Phase 2 verification test indicated side shear values within the Gneiss layer comparable to the Phase 1 test findings. The casing was found to contribute primarily as a borehole stabilizing mechanism and to haved no significant effect on the load distribution within the bond zone.

For design of foundations on driven piles, Load and Resistance Factor Design (LRFD) is increasingly replacing the conventional Allowable Stress Design (ASD) approach. LRFD separates the uncertainty in loading conditions from the uncertainty in resistances, while the ASD approach uses a single "global factor of safety" to cover all uncertainties. Concerning resistances, LRFD uses a range of "resistance factors" adjusted to the method of capacity evaluation and level of quality control and assurance during construction, while the previous ASD approach often considers only the method of capacity evaluation but not the amount of testing. Considerable confusion exists as to how to best apply the new LRFD methodology and reap its potential benefits to affect a safe and economical foundation. This paper attempts to address some of the issues and answer questions associated with the newly implemented method. The benefits of full scale pile testing, by either static or dynamic methods, and of an increased amount of such testing, are illustrated by numerical examples. After a review of the global factors of safety for different codes, pile designs using ASD global factors of safety are compared with designs produced using the most recently developed LRFD resistance factors from AASHTO Specifications. Among the capacity evaluation methods will be static analysis, dynamic formula, wave equation, dynamic testing and static testing. Although the prime emphasis is the AASHTO specification, comparisons are also made with resistance factors from current standards from Europe, Australia, and Canada.

This paper describes a process by which pile load test data can be used to assist in the prediction of pile foundation settlements. In the interpretation of the load test results, the critical importance of making allowance for the load test setup and possible interaction effects is emphasized, because of the potential for over-estimation of pile stiffness. Two examples are given, one of an unsuccessful use of pile load test data for pile foundation settlement prediction, and the other of a more successful outcome. The reasons for the unsuccessful prediction are examined. It is found that successful prediction of the test pile settlement does not guarantee that the overall settlement of the foundation system will be predicted successfully.

The quality of concrete and integrity of deep diaphragm walls in any given project is very important to ensure safety within the excavation and for the long term performance of the structural element. Not only is the structural strength of the wall important, but also its effectiveness in preventing water seepage, which could be compromised by soil or slurry intrusions among other defects. For these reasons, major civil works frequently require thorough testing of deep foundation elements to assure adherence to material quality specifications. For deep foundations, Crosshole Sonic Logging (CSL) is the most common integrity test measuring the travel time of ultrasonic pulses in the concrete. A low wave speed indicates inferior concrete quality, while a completely missing signal indicates an anomaly or defect. The test is frequently used for the integrity assessment of foundation piles, but is less commonly applied to diaphragm walls. This paper describes the construction and CSL testing of several tunnel access shafts ranging from 16 to 20 m in diameter, which serve as part of a newly constructed 62 km long wastewater tunnel in Mexico. The diaphragm walls were installed to a depth of up to 45 m, and the individual panels were up to 6 m wide. Because of their great depth and large lateral extent, the maximum possible distance between CSL probes, the verticality of the inspection tubes, and the effect of variable tube distances on the CSL measurements were important questions that arose during the planning stage. This paper presents CSL test results that answer these questions.

Full-scale load tests on 31 large footings situated on 13 different quartz-silica sand sites are used to develop a direct means for evaluating the vertical load-displacement and capacity response using tip resistances (q_c) from cone penetration tests (CPT). Only large size foundations with footing widths 0.5 m ≤ B ≤ 6 m were considered in order to avert difficulties found in scaling of small model test results. As no clear peak was observed, a reference "capacity" criterion is taken as the load corresponding to the s/B = 10% criterion, where s = footing displacement. It is found that the applied footing stress (q) vs. displacement (s/B) curves for all cases are unified when the foundation stress is normalized by the cone tip resistance.

Some of the difficulties which may be encountered with traditional full-scale static load pull out tests both in terms of practicalities of setting up the test and interpretation of the results are presented. A simple model is described that appears to match the behaviour of the reinforced concrete under tension and that of characterising the skin friction behaviour with a single hyperbolic function, such as that suggested by Kondner (1963), Chin (1970, 1972) and employed in the Cemsolve method of pile behaviour analysis, Fleming (1992). An alternative to a traditional pullout test is now finding wide acceptance with the introduction of bi-directional load testing. The innovative solutions provided by casting a loading jack within a test pile itself are described in detail; and offer two approaches, in one, an additional reaction pile is located below the test pile - installed at the same time but to a greater depth, and the second is a method of analysis of the test results from a conventional bi-directional test which is used to estimate the upward behaviour derived from the geotechnical behaviour of the components measured.

Efficient pile design requires an understanding of the engineering properties of the site, the pile, and the complex changes that occur during installation.Engineers usually specify tests to verify the resistance and the behavior of the hammer-pile-soil combination. Static testing requires significant time and expense. A dynamic test monitors the response of the pile-soil system during hammer impact, investigates installation parameters and resistance, and confirms pile integrity. The usability and reliability of dynamic tests have improved with better instrumentation and computing capabilities. Dynamic tests are relatively inexpensive, cause only minor delay to the project, can be performed on any accessible pile, and are now routinely used for both driven and drilled piles. An impact weight of only 1.5% of the desired static resistance provides a low-cost alternative when testing high-capacity piles. Multiple restrikes allow the engineer to investigate changes in driven pile resistance with time and improve the foundation design. A refined wave equation analysis using the dynamic test results provides reliable installation criteria. This paper discusses the advantages of dynamic testing, with specific examples to illustrate its value to verify static resistance, to investigate time effects on resistance, to refine installation criteria, and to address quality control issues.

The determination of dynamic characteristics of soil-pile system by full-scale lateral dynamic pile load testing is an important aspect in the design of pile foundations subjected to dynamic loads. Field test results are very useful for validating existing linear/nonlinear models which are used to predict the dynamic stiffness and damping of the soil-pile system. This paper presents the results of field lateral dynamic load tests conducted at two different petrochemical complex sites in India and the measured dynamic constants of the soil-pile system. A three-dimensional finite element analysis is performed using ABAQUS to predict the nonlinear response of the soil-pile system under dynamic lateral loads. The lateral stiffness estimated from the FE analysis is compared with stiffness measured from field tests and it shows good agreement.

A variety of methods are available to estimate axial pile capacity for augered cast-in-place piles, however, these methods are generally limited to Allowable Stress Design procedures with little consideration of design reliability. Local and global datasets of shaft resistance design parameters have been evaluated to address the current lack of reliability-based design methods for augercast piling. This paper summarizes the results of static loading tests performed in Western Washington, installed within granular materials and with diameters and lengths ranging from 0.41 to 0.51 m and 9.5 to 29 m, respectively. The preparation of unit shaft resistances is discussed in consideration of strain dependent composite tangent moduli and observed residual loads.Relationships and their statistical characterization are proposed for unit shaft resistance as function of pile head displacement and relative density (i.e., Standard Penetration Resistance). These data are combined with an existing dataset to represent a global database of β-coefficients. Resistance factors for unit shaft resistance and β-coefficients at the strength limit calibrated using First-Order Second Moment and Monte Carlo methods are proposed for use in Load and Resistance Factor Design.

Dynamic formulas were in common use in the early part of the 1900s to estimate capacity of a driven pile, and many comparisons were then made with static loading tests. An ASCE Committee was formed in the 1930s to review and make recommendations on the proper use of dynamic formulas; after almost a decade long study, a report was issued in May 1941. The report generated considerable controversy and a remarkable 28 discussions in the Proceedings of the ASCE by several very high profile engineers. Considering the current renewed search by some agencies to find a better dynamic formula, primarily to increase the LRFD resistance factor to make designs more economical, it is prudent that we revisit this work to avoid repeating some of the same mistakes. Our review of the extensive discussion comments is presented to better define the problem, and to produce more realistic expectations of what can be achieved by a dynamic formula. The discussions also included to a lesser extent considerations of static loading test procedures and interpretations, which are also discussed in this paper.