Pile Setup in Cohesive Soil. II: Analytical Quantifications and Design Recommendations

Ng, Kam; Suleiman, Muhannad T.; Sritharan, Sri

doi:10.1061/(asce)gt.1943-5606.0000753

Cited by 49 publications

(9 citation statements)

References 12 publications

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“…Several methods have been proposed, as summarized in Table 2-6, to estimate set-up based on PDA and/or static load tests, and most assume the resistance increases proportionately with the logarithm of time after the EOID (Bullock et al, 2005;Haque et al, 2017;Haque & Abu-Farsakh, 2019;Karlsrud et al, 2005;Ng et al, 2013b;Skov & Denver, 1988;Svinkin & Skov, 2000). Komurka et al (2003) suggests the logarithmic increase in capacity can be divided into three phases, as shown in Fig.…”

Section: Design Methods To Predict the Time-dependent Capacitymentioning

confidence: 99%

Reliability-based Design for Axially Loaded Driven Piles in Glacial Deposits

Jesswein

2024

Preprint

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Many factors and uncertainties, especially from the soil conditions, challenge the accuracy of a pile design for the geotechnical ultimate limit state (ULS) and serviceability limit state (SLS). The uncertainties can be contributed by the inconsistent material properties of glacial deposits or a lack of provisions by many design methods for the pile set-up, which is an increase in the pile capacity with time. Thus, for driven steel piles subjected to static and maintained axial loads, the goal of this research was to improve the predictability of these limit states by modifying reliability-based design (RBD) methods. A database was collected first in this thesis with a total of 120 piles subjected to static and/or Pile Driving Analyzer (PDA) tests. These tests were used to evaluate the accuracy of several existing design methods that predict the pile capacity with in-situ measurements, particularly by the standard penetration test (SPT) or piezocone penetration test (CPTu). Since existing methods commonly overestimated the capacity or exhibited significant variations in their predictions, correlations were conducted between results from the in-situ and pile tests to develop new design methods to better consider the soil content and set-up time. Many existing set-up prediction methods rely on time-consuming laboratory tests, but this study offers a practical CPTu-based approach. Afterwards, reliability analyses were performed to help designers account for the uncertainties in designs and estimate the factored resistance for the ULS and SLS. Although a few studies have previously incorporated set-up into RBDs for the ULS, very few, if any, have incorporated set-up for the SLS; thus, this thesis presents a series of resistance factors that were calibrated by Monte Carlos simulation for a range of set-up to end-of-driving resistance ratios and allowable settlements. The findings demonstrate the benefits of versatile methods that consider a range of conditions, such as set-up time, soil classification, and pile geometry. In addition, economic benefits may be received for designs by using a greater factored resistance at a set-up time compared to the end-of-pile-driving condition. Overall, the findings can assist practitioners to mitigate geotechnical risks and deliver more economic and reliable pile designs.

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Section: Design Methods To Predict the Time-dependent Capacitymentioning

confidence: 99%

Reliability-based Design for Axially Loaded Driven Piles in Glacial Deposits

Jesswein

2024

Preprint

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“…Two improved analytical methods with their corresponding resistance factors were subsequently developed to better quantify pile resistance increase over time in cohesive soils. The new methods were based on soil properties determined from the widely used Standard Penetration Test (SPT) and Cone Penetration Test (CPT) combined with the Wave Equation Analysis Program (WEAP) and CAPWAP dynamic analysis methods (Ng et al 2013a(Ng et al , 2013b).…”

Section: Resistance Factors Calibrationmentioning

confidence: 99%

Evaluation of Regionally Calibrated Load and Resistance Factor-Design Method Used for Driven-Steel H-Piles

et al. 2020

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Since October 2007, the Federal Highway Administration (FHWA) has required the implementation of LRFD methods in all new bridge designs, including pile design. The resistance factors provided nationally for LRFD of driven piles are relatively conservative. Therefore, the Iowa Department of Transportation and Iowa State University collaborated and established regional resistance factors that are more efficient than those provided in the AASHTO Specifications, which are complemented with improved construction control methods. Iowa's LRFD guidelines for piles have been used in enough completed projects since 2012, allowing an assessment of the accuracy of the regional resistance factors and construction control methods. The piles used in these projects included both end-bearing piles in rock and friction piles. The friction piles were installed in cohesive, noncohesive, and mixed soil sites. The evaluation for the different pile categories and soil types found that the regional LRFD resistance factors developed were successfully applied in Iowa's driven pile design and effectively reduced the piles' contract lengths, resulting in cost-benefit over AASHTO's recommended resistance factors.

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“…It is well known that the axial resistance of piles driven in soils increases with time after driving (1)(2)(3)(4). This phenomenon is called pile setup or freeze and has been reported and discussed by many researchers (e.g., 1,[4][5][6][7]. The setup phenomenon that occurs in soils can be attributed to dissipation of excess pore water pressure (or consolidation), thixotropy, and aging.…”

mentioning

confidence: 99%

“…The setup phenomenon that occurs in soils can be attributed to dissipation of excess pore water pressure (or consolidation), thixotropy, and aging. Several empirical (e.g., 8, 9), numerical (e.g., 10,11), and analytical techniques (e.g., 4,12) have been proposed and developed over the past few decades to predict the amount of setup with time. In addition, several researchers (e.g., 4-7, 10) have conducted full-scale experimental field tests to measure the increase in pile resistance with time using static or dynamic tests or both.…”

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confidence: 99%

Case Study on Instrumenting and Testing Full-Scale Test Piles for Evaluating Setup Phenomenon

Haque

Abu-Farsakh

Chen

et al. 2014

Transportation Research Record: Journal of the Transportation R

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Over time, piles driven in cohesive soils usually experience a large increase in resistance, known as setup or freeze. Dynamic load tests (DLT) and static load tests (SLT) are usually performed to verify the axial resistances of piles at specific times after end of driving (EOD) and to quantify these resistances. An extensive field testing program was performed on full-scale instrumented precast prestressed concrete piles driven in cohesive soils at the Bayou Lacassine Bridge in Louisiana, to evaluate the pile setup phenomenon. The testing program included instrumenting two full-scale test piles with a network of vibrating wire strain gauges, pressure cells, and piezometers and instrumenting the surrounding soils with multilevel piezometers. Five SLTs and three DLTs were conducted on each test pile at different times after EOD to quantify the magnitude of setup. Measurements from the load tests on both piles confirmed that the pile setup after EOD followed a logarithmic rate with time. An increase in piles’ total resistances (or setup) of 1.60 to 1.77 times the EOD resistances was observed after the final restrikes. Piezometer data demonstrated a close relationship between the dissipation of excess pore water pressures that were generated during pile driving, following EOD, and pile setup. The load transfer curves derived from the strain gauge measurements were used to separate the side and tip resistance profiles from the total resistance. Piezometers installed in the ground showed that the influence zone, caused by pile driving, extends beyond the 3B distance (B = pile width).

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Pile Setup in Cohesive Soil. II: Analytical Quantifications and Design Recommendations

Cited by 49 publications

References 12 publications

Reliability-based Design for Axially Loaded Driven Piles in Glacial Deposits

Reliability-based Design for Axially Loaded Driven Piles in Glacial Deposits

Evaluation of Regionally Calibrated Load and Resistance Factor-Design Method Used for Driven-Steel H-Piles

Case Study on Instrumenting and Testing Full-Scale Test Piles for Evaluating Setup Phenomenon

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