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Sidney, Canada

Hai N.M.,Thu Dau Mot University | Fellenius B.H.,2475 Rothesay Avenue
Geotechnical Special Publication | Year: 2014

Static loading tests using single-level O-cells were carried out in mid-2008 on two bored piles constructed at the Binh Loi Bridge, crossing the Saigon River at Ho Chi Minh City, Vietnam. The soils consist of surficial layers of soft clay and silt to 11 and 15 m depth on compact silty sand to about 55 m depth followed by dense to very dense silty sand. Two bored piles, 2.0 m and 1.5 m in diameter, were installed to 73.5 m and 73.0 m depth, respectively, and constructed using reverse circulation technique and bucket drill with casing advanced ahead of the hole. Drilling slurry was composed of polymer slurry for the 2.0-m diameter pile and bentonite slurry for the 1.5-m diameter pile. For both piles, the O-cell assembly was attached to a reinforcing cage lowered into the stabilized hole to 11.4 and 11.6 m, respectively, above the pile toe, five and two days after completing drilling and cleaning, respectively. Each reinforcing cage was instrumented with two pairs of diametrically opposed vibrating wire strain gauges at three levels below and five levels above the O-cell level. The static loading tests were performed 49 and 28 days, respectively, after the piles had been concreted. The strain-gauge records, when based on the nominal pile diameters, indicated Young's modulus values of about 25 GPa for the nominal cross-sections of the piles. Analysis of the records showed that residual load had developed during the wait time. The unit shaft resistance above the O-cell for the 2.0 m diameter, polymer-slurry constructed pile was moderately larger than that for the 1.5-m diameter, bentonite-slurry constructed pile. Detailed analysis showed the shaft resistance to be post-peak softening. The pile toe stress-movement responses were essentially linear and almost identical for the two piles. © 2014 American Society of Civil Engineers. Source

Ryul K.S.,Dong - A University | Gyo C.S.,Dong - A University | Dung N.T.,Dong - A University | Fellenius B.H.,2475 Rothesay Avenue
Geotechnical Special Publication | Year: 2012

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. © 2012 American Society of Civil Engineers. Source

Naesgaard E.,Naesgaard Geotechnical Ltd. | Amini A.,Naesgaard Geotechnical Ltd. | Uthayakumar U.M.,EXP Inc | Fellenius B.H.,2475 Rothesay Avenue
Geotechnical Special Publication | Year: 2012

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. © 2012 American Society of Civil Engineers. Source

Kulesza R.L.,Bechtel Corporation | Fellenius B.H.,2475 Rothesay Avenue
Geotechnical Special Publication | Year: 2012

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. © 2012 American Society of Civil Engineers. Source

Fellenius B.H.,2475 Rothesay Avenue
DFI Journal | Year: 2015

Analysis of results from a static loading tests on an instrumented pile usually assumes that the gage determined loads represent the true loads in the test pile. However, more often than not, residual load will have been present in the pile at the start of the static test. Disregarding these in the analysis will misrepresent the load-movement response and the loads determined from the strain-gage instrumentation, as presented in the paper. The results of three static loading tests: A 400 mm diameter, 45 m long, concrete filled, closed toe, steel pipe pile driven in soft clay, a 460 mm diameter, 22 m long bored pile (screw pile) in silt and sand and stiff clay, and a 600 mm diameter, 15 m long, jacked-in concrete pile in a residual, dense, silty sandy weathered sandstone. The measured load distributions are corrected for residual load, demonstrating the interdependence of the distributions of "False" and "True" distributions of load. © 2015 Deep Foundations Institute. Source

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