Evaluation of Existing Static Design Methods for Prediction of Large Diameter Open-End Pile Resistance

IFCEE 2021 ◽  
2021 ◽  
Author(s):  
Kathryn Petek ◽  
Jennifer Nicks ◽  
Michael McVay
Keyword(s):  
Large Diameter ◽  
Design Methods ◽  
Pile Resistance

Hydrodynamic Forces on Subsea Pipelines due to Orbital Wave Effects

2013 ◽  
Author(s):  
Annelise Karreman ◽  
Jeremy Leggoe ◽  
Terry Griffiths ◽  
Lisa King ◽  
Nino Fogliani
Keyword(s):  
Vertical Velocity ◽  
Large Diameter ◽  
Significant Proportion ◽  
Economic Benefits ◽  
Hydrodynamic Forces ◽  
Design Methods ◽  
Fundamental Aspect ◽  
Experimental Investigations ◽  
Rectilinear Motion ◽  
Particle Paths

Ensuring pipeline stability is a fundamental aspect of subsea pipeline design and can contribute a significant proportion of project costs in regions with large diameter trunklines, shallow water and severe geotechnical and metocean conditions [1]. Reducing the conservatism and simplifications of existing pipeline stabilisation design methods therefore offers economic benefits to hydrocarbon producers necessary to ensure the ongoing viability of projects in these regions. To realise this potential and reduce the conservatism of the existing design methods, a more accurate understanding of the hydrodynamic loads exerted by waves and currents is required. This paper investigates one of the inherent assumptions incorporated into the existing design methods through the arrangement of previous experimental investigations to determine whether rectilinear motion provides a reasonable approximation to simulate the near seabed orbital particle paths in wind-generated waves. This assumption is based on the flattening of particle paths to ellipsoids with depth and ignores the small vertical velocity components near the seabed. Based on the hydrodynamic forces calculated numerically using a validated Computational Fluid Dynamics (CFD) model for rectilinear and orbital wave modelling it is concluded that pipeline stabilisation requirements calculated in accordance with the DNV-RP-F109 absolute lateral static stability design method and rectilinear wave motion assumption are conservative. It is also concluded that the hydrodynamic force asymmetry in favour of the reverse half wave cycle caused by the vertical velocity components in orbital wave conditions requires further consideration to determine the implication for dynamic lateral stability design methods.

Comparison of Cyclic P-Y Methods for Offshore Wind Turbine Monopiles Subjected to Extreme Storm Loading

2015 ◽  
Author(s):  
Wystan Carswell ◽  
Casey Fontana ◽  
Sanjay R. Arwade ◽  
Don J. DeGroot ◽  
Andrew T. Myers
Keyword(s):  
Wind Turbine ◽  
Large Diameter ◽  
Small Diameter ◽  
Design Guidelines ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Extreme Storm ◽  
Design Loads ◽  
Number Of Cycles ◽  
Pile Resistance

Approximately 75% of installed offshore wind turbines (OWTs) are supported by monopiles, a foundation whose design is dominated by lateral loading. Monopiles are typically designed using the p-y method which models soil-pile resistance using decoupled, nonlinear elastic Winkler springs. Because cyclic soil behavior is difficult to predict, the cyclic p-y method accounts for cyclic soil-pile interaction using a quasistatic analysis with cyclic p-y curves representing lower-bound soil resistance. This paper compares the Matlock (1970) and Dunnavant & O’Neill (1989) p-y curve methods, and the p-y degradation models from Rajashree & Sundaravadivelu (1996) and Dunnavant & O’Neill (1989) for a 6 m diameter monopile in stiff clay subjected to storm loading. Because the Matlock (1970) cyclic p-y curves are independent of the number of load cycles, the static p-y curves were used in conjunction with the Rajashree & Sundaravadivelu (1996) p-y degradation method in order to take number of cycles into account. All of the p-y methods were developed for small diameter piles, therefore it should be noted that the extrapolation of these methods for large diameter OWT monopiles may not be physically accurate; however, the Matlock (1970) curves are still the curves predominantly recommended in OWT design guidelines. The National Renewable Energy Laboratory wind turbine analysis program FAST was used to produce mudline design loads representative of extreme storm loading. These design loads were used as the load input to cyclic p-y analysis. Deformed pile shapes as a result of the design load are compared for each of the cyclic p-y methods as well as pile head displacement and rotation and degradation of soil-pile resistance with increasing number of cycles.

Calibration of Resistance Factors for Axially Loaded Concrete Piles Driven into Soft Soils

2008 ◽  
Vol 2045 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Sungmin Yoon ◽  
Murad Y. Abu-Farsakh ◽  
Ching Tsai ◽  
Zhongjie Zhang
Keyword(s):  
Prestressed Concrete ◽  
Prediction Method ◽  
Direct Methods ◽  
Load Resistance ◽  
Design Methods ◽  
Resistance Factors ◽  
Concrete Piles ◽  
Load Tests ◽  
Pile Load Tests ◽  
Pile Resistance

The evaluation of axial load resistance of piles driven into soft Louisiana soils based on reliability theory is presented. Forty-two square precast, prestressed, concrete piles that were tested to failure were included in the investigation. The predictions of pile resistances were based on static analysis (α-method for clay and Nordlund method for sand) and three cone penetration test (CPT) direct methods: the Schmertmann, De Ruiter–Beringen, and Bustamante–Gianeselli methods. In addition, dynamic measurements with signal matching analysis of pile resistances using CAPWAP, which is based on the measured force and velocity signals obtained near the pile top during driving, were evaluated. The Davisson and modified Davisson interpretation methods were used to determine the measured ultimate load-carrying resistances from pile load tests. The predicted ultimate pile resistances obtained by using the different prediction methods were compared with the measured resistances determined from pile load tests. Statistical analyses were carried out to evaluate the capability of the prediction design methods to estimate the measured ultimate pile resistance of driven piles. The results showed that the static method overpredicted the pile resistance, whereas the dynamic measurement with signal matching analysis (CAPWAP end-of-driving and 14-day beginning-of-restrike) underpredicted the pile resistance. Of the three direct CPT methods, the De Ruiter–Beringen method was the most consistent prediction method with the lowest coefficient of variation. Reliability-based analyses, by using the first-order, second-moment method, also were conducted to calibrate the resistance factors (φ) for the investigated pile design methods. The resistance factors for different design methods were determined and compared with AASHTO recommendation values. The calibration showed that De Ruiter–Beringen method has a higher resistance factor (φDe Ruiter = 0.64) than the other two CPT methods.

New design methods for large diameter piles under lateral loading for offshore wind applications

2015 ◽  
pp. 705-710 ◽  
Author(s):  
B Byrne ◽  
R McAdam ◽  
H Burd ◽  
G Houlsby ◽  
C Martin ◽  
...  
Keyword(s):  
Large Diameter ◽  
Design Methods ◽  
Lateral Loading ◽  
Offshore Wind

Development of a digital SEM

1991 ◽  
Vol 49 ◽  
pp. 358-359
Author(s):  
A. Yamada ◽  
A. Shibano ◽  
K. Harasawa ◽  
T. Kobayashi ◽  
H. Fukuda ◽  
...  
Keyword(s):  
Large Diameter ◽  
Objective Lens ◽  
Large Specimen ◽  
Backscattered Electrons ◽  
Digital Scanning ◽  
Junction Type ◽  
High Resolution Images ◽  
Working Distance ◽  
Type Detector ◽  
Short Working

A newly developed digital scanning electron microscope, the JSM-6300, has the following features: Equipped with a narrower conical objective lens (OL), it allows high resolution images to be obtained easily at a short working distance (WD) and a large specimen tilt angle. In addition, it is provided with automatic functions and digital image processing functions for ease of operation.Conical C-F lens: The newly developed conical C-F objective lens, having low aberration characteristics over a wide WD range, allows a large-diameter (3-inch) specimen to be tilted up to 60° at short WD, and provides images with low magnifications starting at 10*. On the bottom of the lens, a p n junction type detector is provided to detect backscattered electrons (BE) from the specimen. As the narrower conical 0L increases the secondary electron (SE) detector's field intensity on the specimen surface, high SE image quality is obtained.

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