Progress Reports: December 2005 June 2005 December 2004 June 2004 December 2003 June 2003 December 2002 June 2002 December 2001SUCTION CAISSONS AND VERTICALLY LOADED ANCHORS
Seafloor Characterization for Deepwater Foundation Systems
OBJECTIVE: The challenge of seafloor characterization for deepwater facilities is that the mooring foundations, subsea well trees and flowlines are spread over large areas (tens of thousands of feet across) while the cost of obtaining high-quality geotechnical data for the seafloor is high. Therefore, information from a handful of soil borings is typically extrapolated over thousands of feet to design foundations. This extrapolation leads to uncertainty that could potentially lead to excessively conservative designs or to unreliable designs.The goal of this research is to develop a reliability-based methodology to design offshore foundations with limited seafloor characterization data and to apply this methodology to optimize geotechnical investigation programs. Specific research objectives are:
1. Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
2. Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
3. Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
4. Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.APPROACH: These research objectives are being addressed through completing the following tasks:
Task 1: Develop geologic-dependent models for spatial trends and variability in design data.
Task 2: Develop a methodology to determine the reliability of a foundation in deepwater considering uncertainty in the predictive model and soil properties as well as in the loading conditions.
Task 3: Calibrate models of foundation capacity based on installation data.
Task 4: Develop design charts that relate partial safety or resistance factors to uncertainty in design data for a specified level of reliability and for different foundation configurations and loading conditions.DEPLOYMENT OF RESULTS: Results will be documented in a final report and be published in conference proceedings and journal articles. Results will be useful in developing and updating industry guidelines and standards.
ANTICIPATED PROJECT DURATION: 6 years
PROJECT PLAN FOR YEAR 6 (2004-2005):
Scope of Work:
Task 1 - Developing geologic-dependent models for spatial (both horizontal and vertical) trends and variability in design data, such as foundation capacity for floating structures and pipelines/flowlines. In addition, statistical correction factors and weights are being developed to relate data obtained from other sources (specifically, geophysical information and foundation installation information) to that obtained from a conventional soil boring. The development of these models is being guided by data from various sources and locations that have been compiled through separate industry-sponsored projects (specifically, Unocal, BP and ExxonMobil have sponsored projects at UT to generate, compile and analyze offshore geotechnical in the past several years). We have been able to compile conventional geotechnical data for a number of different offshore fields.
Research during 2004-2005 will focus on developing a reliability framework to accommodate non-normal probability distributions for soil properties and foundation capacity in a practical way.
Task 2 - A methodology is being developed to determine the reliability of a foundation in deepwater considering uncertainties in the predictive model, soil properties, and the loading conditions. Foundation capacity models are being calibrated with laboratory and field tests. We have developed a practical methodology to accommodate highly non-normal probability distributions to accommodate the finite lower bound of foundation capacity and generally non-normal spatial variability in soil properties. Information on the uncertainty in loading conditions is being obtained from an ongoing OTRC-sponsored project on mooring system reliability.
Research during 2004-2005 will focus on calibrating models to predict suction caisson capacity with laboratory and field data. This effort will incorporate information from a related OTRC project where model tests are being performed on suction
Task 3 - Models of foundation capacity are also being calibrated with field data obtained during installation, using information that was compiled in a separate project sponsored by API. Installation information is being related to the ultimate capacity using available models and information on time-dependent increases in capacity after installation. We are also relating installation information to a lower bound or minimum possible capacity. This lower bound can play a significant role in the reliability of the foundation since the load would theoretically need to reach this value before failure is even possible. This work is also significant because the ability to install the foundation is an important design consideration. Driven pile data has been analyzed, and data form suction caisson installations is now being studies.Research during 2004-2004 will focus on developing a methodology to update foundation capacity (both the lower bound and the expected value) with installation information.
Task 4 – Design charts are being developed that relate partial safety or resistance factors to uncertainty in design data for a specified level of reliability and for different foundation configurations and loading conditions. Foundation types being considered include deep foundations, such as driven piles and suction caissons, as well as shallow foundations, such as for flowlines and well systems. This task has been completed for simple cases (normal or lognormal probability distributions, no lower bound, and no incorporation of installation data). Research will continue to extend and complete this work for more general and realistic cases.
Results will be documented in the final report and will provide information to support development of design guidance for suction caissons and anchors.
Anticipated Project Results: The project deliverables include the following:
1. A set of geologic-dependent models to account for spatial variations in foundation capacities for both deep and shallow foundations. These models, when combined with user-supplied information for a specific field or project, will provide valuable information to manage situations where foundations are spread out and not located adjacent to soil borings.
2. Information about the uncertainty in conventional models to predict suction caisson capacity and a methodology to updated the predicted capacity on a project-specific basis using installation data.
3. A reliability-based design framework for suction caissons that can ultimately be used to guide the development of recommended practice guidelines.PRINCIPAL INVESTIGATOR (S) & OTHERS INVOLVED IN PROJECT:
PI(s): Robert B. Gilbert
Date: December 9, 2005Project Name: Seafloor Characterization for Deepwater Production Systems
MMS Project: 362 TO Numbers: 16169/35980
PI: Bob Gilbert
COTR: A. Konczvald
Completion Date: December, 2005
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
1. Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
2. Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
3. Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
4. Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.Progress:
1. Developed a methodology to account for a lower bound on the distribution of foundation capacity in assessing the reliability of the foundation. Our work indicates that this lower bound significantly affects (if not governs) the reliability for typical metocean conditions, typical floating production systems, and typical design factors of safety.
2. Compiled and analyzed database of remolded capacity (capacity during driving) versus measured capacity for 44 sites in soft clay in order to quantify the lower bound on the probability distribution for pile capacity.
3. Compiled a database of suction caisson installation and load-test data. These data have been analyzed to (1) compare predicted to measured installation resistance; (2) evaluate the effect of spatial variations and geologic variations on the installation resistance; and (3) relate the installation resistance to the lower bound capacity of the foundation.
4. Calibrated the most commonly-used model to predict suction caisson capacity (a product of the work at Texas A&M) with test results from 1-g models (in a related UT project) and centrifuge test results. Efforts here focus on the expected capacity, the lower bound capacity, and the variability between the model predictions and the test results.
5. Met with API committee tasked with developing an RP for deepwater foundations. Providing results from this project as information in developing design checking equations and associated factors of safety (or load and resistance factors).All project work has been essentially completed, and the final project report is being prepared.
Reports & Publications:
Najjar, S. S. (2005), Importance of Lower-Bound Capacities in Geotechnical Reliability Assessments,” Ph.D. Dissertation, The University of Texas at Austin, 316 p.Gilbert, R. B., Choi, Y. J., Dangyach, S. and Najjar, S. S. (2005), “Reliability-Based Design Considerations for Deepwater Mooring System Foundations,” Proceedings, ISFOG 2005, Frontiers in Offshore Geotechnics, Perth, Western Australia, 317-324.
Gilbert, R. B., Najjar, S. S. and Choi, Y. J. (2005), “Incorporating Lower-Bound Capacities into LRFD Codes for Pile Foundations,” Proceedings, Geo-Frontiers 2005, Geotechnical Special Publication No. 132 (CD-ROM), ASCE, Reston, Virginia.
Gilbert, R. B., Najjar, S. S. and Shields, M. K. (2005), “Importance of Residual Strengths in Factors of Safety and Reliability,” Proceedings, Geo-Frontiers 2005, 18th GRI Conference on Geosynthetics Research and Development in Progress (CD-ROM), ASCE, Reston, Virginia.
Gilbert, R. B. and Puskar, F. (2005), “Geohazards: An Overview of Probabilistic Approaches and Application to Engineering Design and Risk Assessment for Offshore Facilities,” Proceedings, Offshore Technology Conference, OTC 17676.
Najjar, S. S. and Gilbert, R. B. (2005), “Lower-Bound Estimates of Capacity in Geotechnical Reliability Assessments,” Proceedings,ICOSSAR 2005, Intl. Conf. on Structural Safety and Reliability, Rome, Italy, 955-962.
Gilbert, R. B. (2003), “Reliability-Based Design as a Decision-Making Tool,” Proceedings, International Workshop on Limit State Design in Geotechnical Engineering Practice, Phoon, Honjo and Gilbert (eds.), Cambridge, Massachusetts.
Gilbert, R. B. and Murff, J. D. (2001), “Design Methodologies and Criteria for Suction Caissons for Deepwater Mooring Applications,” Workshop Report, Offshore Technology Research Center, 136 pp.
Gilbert, R. B. and Murff, J. D. (2001), “Identifying Uncertainties in the Design of Suction Caisson Foundations,” Proceedings, International Conference on Geotechnical, Geological and Geophysical Properties of Deepwater Sediments Honoring Wayne A. Dunlap, OTRC, Houston, Texas, 231-242.
Olson, R. E., Rauch, A. F., Gilbert, R. B., Tassoulas, J. L., Aubeny, C. P. and Murff, J. D. (2001), “Toward the design of New Technologies for Deep-Water Anchorages,” Proceedings, Annual International Offshore and Polar Engineering Conference, Stavanger, Norway, in press.
Smith, G. L. and Gilbert, R. B. (2001), “A Simplified Model of Spatial Variability to Evaluate Effects of Spatial Averaging on Foundation Capacity,” Proceedings, International Conference on Structural Safety and Reliability, Huntington Beach, California, in press.
Gilbert, R. B., McBrayer, M. C. and Tang, W. H. (2000), “Statistical Considerations in Calibrating Performance Models with Field Data,” Proceedings of Performance Confirmation of Constructed Geotechnical Facilities, ASCE, GSP No. 94, Amherst, 307-321.
Gilbert, R. B. (2000), “Optimizing Investigation Programs for Offshore Platform Foundations – Effect of Geology on Axial Pile Capacity,” Proceedings,International Young Geotechnical Engineers Conference 2000, University of Southampton.Gambino, S. J. and Gilbert, R.B. (1999), “Modeling Spatial Variability in Pile Capacity for Reliability-Based Design,” Analysis, Design, Construction and Testing of Deep Foundations, Roesset Ed., ASCE Geotechnical Special Publication No. 88, 135-149.
Gilbert, R. B., Stong, T. J., Lang, J. T., Albrecht, R. S. and Dupin, R. M. (1999), “Optimizing Investigation Programs for Offshore Foundations – Effect of Geology on Axial Pile Capacity,” Proceedings, 2nd International Conf. on Seabed Geotechnics, IBC Ltd., London.
Gilbert, R. B., Gambino, S. J. and Dupin, R. M. (1999), “Reliability-Based Approach for Foundation Design without Site-Specific Soil Borings,” Proceedings, Offshore Technology Conference, Houston, Texas, 631-640.
Date: June 2005
Project Name: Seafloor Characterization for Deepwater Production Systems
MMS Project: 362 TO Numbers: 16169/35980
PI: Bob Gilbert
COTR: A. Konczvald
Estimated Completion Date: September, 2005
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
Progress:
- Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
- Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
- Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
- Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.
Work over the final 3 months of this project will involve preparing a final report.
- Developed a methodology to account for a lower bound on the distribution of foundation capacity in assessing the reliability of the foundation. Our work indicates that this lower bound significantly affects (if not governs) the reliability for typical metocean conditions, typical floating production systems, and typical design factors of safety. Therefore, our efforts are now focused on relating calibrating this lower bound capacity with field and model test data and relating it to geologic information, geotechnical investigation data, installation data, and the design factor of safety.
- Compiled and analyzed database of remolded capacity (capacity during driving) versus measured capacity for 44 sites in soft clay. The goals here are to quantify the lower bound on the probability distribution for the total pile capacity and to provide a way to update the foundation reliability based on installation information.
- Completed the compilation of a database of suction caisson installation and load-test data. These data have been analyzed to (1) compare predicted to measured installation resistance; (2) evaluate the effect of spatial variations and geologic variations on the installation resistance; and (3) relate the installation resistance to the lower bound capacity of the foundation.
- Completed calibration of the most commonly-used model to predict suction caisson capacity (a product of the ongoing work at Texas A&M) with test results from 1-g models (in a related UT project) and centrifuge test results. The calibration focused predicting the (a)expected capacity, (b) lower bound capacity, and (c) variability between the model predictions and the test results.
- Continued to provide project results (information relative to design checking equations and associated factors of safety (or load and resistance factors) to an API committee tasked with developing an RP for deepwater foundations.
Reports & Publications:
Najjar, S. S. (2005), Importance of Lower-Bound Capacities in Geotechnical Reliability Assessments,” Ph.D. Dissertation, The University of Texas at Austin, 316 p.
Najjar, S. S. and Gilbert, R. B. (2005), “Lower-Bound Estimates of Capacity in Geotechnical Reliability Assessments,” Proceedings, Intl. Conf. on Structural Safety and Reliability, Rome, Italy, in press.
Gilbert, R. B., Najjar, S. S. and Choi, Y. J. (2005), “Incorporating Lower-Bound Capacities into LRFD Codes for Pile Foundations,” Proceedings, Geo-Frontiers Congress, Austin, Texas.
Gilbert, R. B. (2003), “Reliability-Based Design as a Decision-Making Tool,” Proceedings, International Workshop on Limit State Design in Geotechnical Engineering Practice, Phoon, Honjo and Gilbert (eds.), Cambridge, Massachusetts.
Najjar, S. S., Gilbert, R. B., Liedtke, E. A., and McCarron, B. (2003), “Tilt Table Test for Interface Shear Resistance between Flowlines and Soils,” Proceedings, 22nd International Conference on Offshore Mechanics and Arctic Engineering, Cancun, in press.
Gilbert, R. B. and Murff, J. D. (2001), “Design Methodologies and Criteria for Suction Caissons for Deepwater Mooring Applications,” Workshop Report, Offshore Technology Research Center, 136 pp.
Gilbert, R. B. and Murff, J. D. (2001), “Identifying Uncertainties in the Design of Suction Caisson Foundations,” Proceedings, International Conference on Geotechnical, Geological and Geophysical Properties of Deepwater Sediments Honoring Wayne A. Dunlap, OTRC, Houston, Texas, in press.
Olson, R. E., Rauch, A. F., Gilbert, R. B., Tassoulas, J. L., Aubeny, C. P. and Murff, J. D. (2001), “Toward the design of New Technologies for Deep-Water Anchorages,” Proceedings, Annual International Offshore and Polar Engineering Conference, Stavanger, Norway, in press.
Date: December, 2004
Project Title: Seafloor Characterization for Deepwater Production Systems
MMS Project: 362 TO Numbers: 16169/35980
PI: Bob Gilbert
COTR: A. Konczvald
Estimated Completion Date: August, 2005
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
Progress:1. Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
2. Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
3. Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
4. Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.Recent Progress:
1. Developed a methodology to account for a lower bound on the distribution of foundation capacity in assessing the reliability of the foundation. This work indicates that this lower bound significantly affects (if not governs) the reliability for typical metocean conditions, typical floating production systems, and typical design factors of safety. Therefore, our efforts are now focused on relating this lower bound capacity to geologic information, geotechnical investigation data, installation data, and the design factor of safety.
2. Compiled and analyzed database of remolded capacity (capacity during driving) versus measured capacity for 44 sites in soft clay. The goals here are to quantify the lower bound on the probability distribution for the total pile capacity and to provide a way to update the foundation reliability based on installation information.
3. Compiling a database of suction caisson installation data, including full-scale installations for MODUs. We will be using these data to (1) compare predicted to measured installation resistance; (2) evaluate the effect of spatial variations and geologic variations on the installation resistance; and (3) relate the installation resistance to the lower bound capacity of the foundation.
4. Calibrating the conventional model to predict suction caisson capacity (a product of the ongoing work at Texas A&M) with test results from 1-g models (in a related UT project) and centrifuge test results. Efforts here focus on the expected capacity, the lower bound capacity, and the variability between the model predictions and the test results.
5. Met with API committee tasked with developing an RP for deepwater foundations. Providing results from this project as information in developing design checking equations and associated factors of safety (or load and resistance factors).Work is now focused on calibrating design models, with an emphasis on the lower bound capacity for both wave-dominated and current-dominated loading conditions, and on preparing a final report.
Reports & Publications:Najjar, S. S. and Gilbert, R. B. (2005), “Lower-Bound Estimates of Capacity in Geotechnical Reliability Assessments,” Proceedings, Intl. Conf. on Structural Safety and Reliability, Rome, Italy, in press.
Return to top
Gilbert, R. B., Najjar, S. S. and Choi, Y. J. (2005), “Incorporating Lower-Bound Capacities into LRFD Codes for Pile Foundations,” Proceedings, Geo-Frontiers Congress, Austin, Texas, in press.
Gilbert, R. B. (2003), “Reliability-Based Design as a Decision-Making Tool,” Proceedings, International Workshop on Limit State Design in Geotechnical Engineering Practice, Phoon, Honjo and Gilbert (eds.), Cambridge, Massachusetts.
Najjar, S. S., Gilbert, R. B., Liedtke, E. A., and McCarron, B. (2003), “Tilt Table Test for Interface Shear Resistance between Flowlines and Soils,” Proceedings, 22nd International Conference on Offshore Mechanics and Arctic Engineering,Cancun, in press.
Date: June 2004Project Name: Seafloor Characterization for Deepwater Production Systems
Project Number: 362 Task Order: 16169
Principal Investigators: Bob Gilbert
Estimated Completion Date: September, 2005
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
1. Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
2. Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
3. Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
4. Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.Progress: Recent progress includes:
1. Developed a methodology to account for a lower bound on the distribution of foundation capacity in assessing the reliability of the foundation. Preliminary results indicate that this lower bound significantly affects (if not governs) the reliability for typical metocean conditions, typical floating production systems, and typical design factors of safety. Therefore, our efforts are now focused on relating this lower bound capacity to geologic information, geotechnical investigation data, installation data, and the design factor of safety.
2. Compiled and analyzed database of remolded capacity (capacity during driving) versus measured capacity for 44 sites in soft clay. The goals here are to quantify the lower bound on the probability distribution for the total pile capacity and to provide a way to update the foundation reliability based on installation information.
3. Compiling a database of suction caisson installation data, including full-scale installations for MODUs. We will be using these data to (1) compare predicted to measured installation resistance; (2) evaluate the effect of spatial variations and geologic variations on the installation resistance; and (3) relate the installation resistance to the lower bound capacity of the foundation.
4. Calibrating the conventional model to predict suction caisson capacity (a product of the ongoing work at Texas A&M) with test results from 1-g models (in a related UT project) and centrifuge test results. Efforts here focus on the expected capacity, the lower bound capacity, and the variability between the model predictions and the test results.
5. Met with API committee tasked with developing an RP for deepwater foundations. Providing results from this project as information in developing design checking equations and associated factors of safety (or load and resistance factors).Work during the next 6 months will focus on the expanding the quantity of deepwater data (both geologic and geotechnical properties) and calibrating design models, with an emphasis on the lower bound capacity for both wave-dominated and current-dominated loading conditions.
Reports & Publications:Gilbert, R. B. and Najjar, S. S. (2004), “Importance of Lower-Bound on Geotechnical Reliability,” Geotechnique, in press.
Return to top
Gilbert, R. B. (2003), “Reliability-Based Design as a Decision-Making Tool,” LSD2003: International Workshop on Limit State Design in Geotechnical Engineering Practice, Cambridge, Mass., in press.
Najjar, S. S., Gilbert, R. B., Liedtke, E. A., and McCarron, B. (2003), “Tilt Table Test for Interface Shear Resistance between Flowlines and Soils,” Proceedings, 22nd International Conference on Offshore Mechanics and Arctic Engineering, Cancun, in press.
Date: December 2003
Project Name: Seafloor Characterization for Deepwater Production Systems
TEES Project Number: 32558-58874 MMS Task Order: 16169 MMS Project Number: 362
Principal Investigators: Bob Gilbert
Estimated Completion Date: December, 2005
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
1. Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
2. Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
3. Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
4. Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.Progress:
1. Developed a methodology to account for a lower bound on the distribution of foundation capacity in assessing the reliability of the foundation. Preliminary results indicate that this lower bound significantly affects (if not governs) the foundation reliability for typical metocean conditions, typical floating production systems, and typical design factors of safety. Therefore, our efforts are now focused on relating this lower bound capacity to geologic information, geotechnical investigation data, installation data, and the design factor of safety.
2. Compiled and analyzed database of remolded capacity (capacity during driving) versus measured capacity for 44 sites in soft clay. The goals here are to quantify the lower bound on the probability distribution for the total pile capacity and to provide a way to update the foundation reliability based on installation information.
3. Compiling a database of suction caisson installation data, including full-scale installations for MODU’s. We will use these data to (1) compare predicted to measured installation resistance; (2) evaluate the effect of spatial variations and geologic variations on the installation resistance; and (3) relate the installation resistance to the lower bound capacity of the foundation.
4. Calibrating the conventional model to predict suction caisson capacity (a product of the ongoing work at Texas A&M) with test results from 1-g models (in a related UT project) and centrifuge test results. Efforts here focus on the expected capacity, the lower bound capacity, and the variability between the model predictions and the test results.Work during the next 6 months will focus on the expanding the quantity of deepwater data (both geologic and geotechnical properties) and calibrating design models, with an emphasis on the lower bound capacity for both wave-dominated and current-dominated loading conditions.
Reports & Publications:Gilbert, R. B. (2003), “Reliability-Based Design as a Decision-Making Tool,” LSD2003: International Workshop on Limit State Design in Geotechnical Engineering Practice, Cambridge, Mass., in press.
Date: June, 2003
Project Name: Seafloor Characterization for Deepwater Production Systems
Project Number: 32558-58874 Task Order: 16169
Principal Investigators: Bob Gilbert
Estimated Completion Date: 12/05
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
1. Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
2. Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
3. Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
4. Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.Progress:
1. To quantify the lower bound on the probability distribution for the total pile capacity, compiled and analyzed database of remolded capacity (capacity during driving) versus measured capacity for 44 sites with driven pipe piles in soft clay. Now extending the compilation and analysis to include suction caisson data. We anticipate that this information will be very helpful in reliability assessments since the lower tail of the capacity distribution governs the foundation reliability. It will also provide a way to update the foundation reliability based on installation information.
2. Developing a theoretical framework to practically account for a lower bound, such as the capacity with remolded strengths, in a reliability analysis.
3. Developing a test method to characterize the resistance that soil will provide to thermally-induced movements in pipelines and flowlines. Are analyzing data that we have developed with this test method from multiple deepwater sites in the Gulf of Mexico to understand how the soil mineralogy and the flowline/pipeline coating affect the resistance.Reports & Publications:
Najjar, S. S., Gilbert, R. B., Liedtke, E. A., and McCarron, B. (2003), “Tilt Table Test for Interface Shear Resistance between Flowlines and Soils,” Proceedings, 22nd International Conference on Offshore Mechanics and Arctic Engineering, Cancun, in press.
Al Awar, Z. (2002), “Developing a Model for Axial Pile Capacity in an Offshore Field,” M. S. Thesis, The University of Texas at Austin, Austin, Tx.Altuntas, C. (2002), “Development of a Statistical Model for Laterally Loaded Pile Analysis to Reduce Uncertainty in an Offshore Field,” M. S. Thesis, The University of Texas at Austin, Austin, Tx.
Van Shaar, S. (2002), “Dynamic Analysis for Suction Caissons and Geologic Model for Makassar Strait, M. S. Thesis, The University of Texas at Austin, Austin, Tx.
Gilbert, R. B. and Murff, J. D. (2001), “Design Methodologies and Criteria for Suction Caissons for Deepwater Mooring Applications,” Workshop Report, Offshore Technology Research Center, 136 pp.
Gilbert, R. B. and Murff, J. D. (2001), “Identifying Uncertainties in the Design of Suction Caisson Foundations,” Proceedings, International Conference on Geotechnical, Geological and Geophysical Properties of Deepwater Sediments Honoring Wayne A. Dunlap, OTRC, Houston, Texas, in press.
Olson, R. E., Rauch, A. F., Gilbert, R. B., Tassoulas, J. L., Aubeny, C. P. and Murff, J. D. (2001), “Toward the design of New Technologies for Deep-Water Anchorages,” Proceedings, Annual International Offshore and Polar Engineering Conference, Stavanger, Norway, in press.
Smith, G. L. and Gilbert, R. B. (2001), “A Simplified Model of Spatial Variability to Evaluate Effects of Spatial Averaging on Foundation Capacity,” Proceedings, International Conference on Structural Safety and Reliability, Huntington Beach, California, in press.
Gilbert, R. B., McBrayer, M. C. and Tang, W. H. (2000), “Statistical Considerations in Calibrating Performance Models with Field Data,” Proceedings of Performance Confirmation of Constructed Geotechnical Facilities, ASCE, GSP No. 94, Amherst, 307-321.
Gilbert, R. B. (2000), “Optimizing Investigation Programs for Offshore Platform Foundations – Effect of Geology on Axial Pile Capacity,” Proceedings,International Young Geotechnical Engineers Conference 2000, University of Southampton.
Gambino, S. J. and Gilbert, R.B. (1999), “Modeling Spatial Variability in Pile Capacity for Reliability-Based Design,” Analysis, Design, Construction and Testing of Deep Foundations, Roesset Ed., ASCE Geotechnical Special Publication No. 88, 135-149.
Gilbert, R. B., Stong, T. J., Lang, J. T., Albrecht, R. S. and Dupin, R. M. (1999), “Optimizing Investigation Programs for Offshore Foundations – Effect of Geology on Axial Pile Capacity,” Proceedings, 2nd International Conf. on Seabed Geotechnics, IBC Ltd., London.
Gilbert, R. B., Gambino, S. J. and Dupin, R. M. (1999), “Reliability-Based Approach for Foundation Design without Site-Specific Soil Borings,” Proceedings, Offshore Technology Conference, Houston, Texas, 631-640.
Date: November 22, 2002
Project Name: Seafloor Characterization for Deepwater Production Systems
Project Number: 32558-58874 Task Order: 16169
Principal Investigators: Bob Gilbert
Estimated Completion Date: December, 2005
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
1. Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
2. Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
3. Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
4. Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.Progress:
Progress since September, 2002:
1. Compiling and analyzing database of remolded capacity (capacity during driving) versus measured capacity for 44 sites in soft clay. The goal here is to quantify the lower bound on the probability distribution for the total pile capacity. If successful, this information will be very helpful in reliability assessments since the lower tail of the capacity distribution governs the foundation reliability. It will also provide a way to update the foundation reliability based on installation information. We are about to undertake a similar analysis on measured data from suction caisson installations.
Progress before September, 2002:
2. Compiled preliminary database for 16 sites in the Gulf of Mexico and the North Sea.
3. Prepared proprietary reports for industry sponsors who contributed data to the initial effort.
4. Analyzed variability in foundation capacity across these fields.
5. Prepared a proposal for a Joint Industry Project to increase the amount of data available to calibrate models to predict foundation capacity.
6. Held five meetings with industry to formulate the JIP proposal.
7. Working with API project to quantify reliability of suction caissons and anchors. An industry workshop was held with 35 participants to discuss site characterization and design for suction caissons and appropriate values for resistance factors. A report from this workshop was issued last year.
8. A related project for a shallow water field in Indonesia has been completed underway. This work involves technology transfer of the reliability-based methodology for site characterization to the Indonesian government.Work during the next year will focus on the expanding the quantity of deepwater data (both geologic and geotechnical properties) and studying the reliability of suction caisson designs under hurricane and loop current loading conditions.
Reports & Publications:
Gilbert, R. B. and Murff, J. D. (2001), “Design Methodologies and Criteria for Suction Caissons for Deepwater Mooring Applications,” Workshop Report, Offshore Technology Research Center, 136 pp.
Gilbert, R. B. and Murff, J. D. (2001), “Identifying Uncertainties in the Design of Suction Caisson Foundations,” Proceedings, International Conference on Geotechnical, Geological and Geophysical Properties of Deepwater Sediments Honoring Wayne A. Dunlap, OTRC, Houston, Texas, in press.
Olson, R. E., Rauch, A. F., Gilbert, R. B., Tassoulas, J. L., Aubeny, C. P. and Murff, J. D. (2001), “Toward the design of New Technologies for Deep-Water Anchorages,” Proceedings, Annual International Offshore and Polar Engineering Conference, Stavanger, Norway, in press.
Smith, G. L. and Gilbert, R. B. (2001), “A Simplified Model of Spatial Variability to Evaluate Effects of Spatial Averaging on Foundation Capacity,” Proceedings, International Conference on Structural Safety and Reliability, Huntington Beach, California, in press.
Gilbert, R. B., McBrayer, M. C. and Tang, W. H. (2000), “Statistical Considerations in Calibrating Performance Models with Field Data,” Proceedings of Performance Confirmation of Constructed Geotechnical Facilities, ASCE, GSP No. 94, Amherst, 307-321.
Gilbert, R. B. (2000), “Optimizing Investigation Programs for Offshore Platform Foundations – Effect of Geology on Axial Pile Capacity,” Proceedings,International Young Geotechnical Engineers Conference 2000, University of Southampton.
Gambino, S. J. and Gilbert, R.B. (1999), “Modeling Spatial Variability in Pile Capacity for Reliability-Based Design,” Analysis, Design, Construction and Testing of Deep Foundations, Roesset Ed., ASCE Geotechnical Special Publication No. 88, 135-149.
Gilbert, R. B., Stong, T. J., Lang, J. T., Albrecht, R. S. and Dupin, R. M. (1999), “Optimizing Investigation Programs for Offshore Foundations – Effect of Geology on Axial Pile Capacity,” Proceedings, 2nd International Conf. on Seabed Geotechnics, IBC Ltd., London.
Gilbert, R. B., Gambino, S. J. and Dupin, R. M. (1999), “Reliability-Based Approach for Foundation Design without Site-Specific Soil Borings,” Proceedings, Offshore Technology Conference, Houston, Texas, 631-640.
Date: July 2002
Project Name: Seafloor Characterization for Deepwater Production Systems
Task Order: 16169 Project Number: 58874
Principal Investigators: R.M. Gilbert
Estimated Completion Date: December, 2005
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
· Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
· Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
· Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
· Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.Progress:
1. Compiled preliminary database for 16 sites in the Gulf of Mexico and the North Sea.
2. Prepared proprietary reports for industry sponsors who contributed data to the initial effort.
3. Analyzed variability in foundation capacity across these fields.
4. Prepared a proposal for a Joint Industry Project to increase the amount of data available to calibrate models to predict foundation capacity.
5. Held four meetings with industry to formulate the JIP proposal.
6. Working with API project to quantify reliability of suction caissons and anchors. An industry workshop was held with 35 participants to discuss site characterization and design for suction caissons and appropriate values for resistance factors. A report from this workshop was issued last year.
7. A related project for a shallow water field in Indonesia is underway. This work involves technology transfer of the reliability-based methodology for site characterization to the Indonesian government.Work during the next year will focus on the starting the JIP and studying the reliability of suction caisson designs under hurricane and loop current loading conditions.
Reports & Publications:
Gilbert, R. B. and Murff, J. D. (2001), “Design Methodologies and Criteria for Suction Caissons for Deepwater Mooring Applications,” Workshop Report, Offshore Technology Research Center
Gilbert, R. B. and Murff, J. D. (2001), “Identifying Uncertainties in the Design of Suction Caisson Foundations,” Proceedings, International Conference on Geotechnical, Geological and Geophysical Properties of Deepwater Sediments Honoring Wayne A. Dunlap, OTRC, Houston, Texas, in press.
Olson, R. E., Rauch, A. F., Gilbert, R. B., Tassoulas, J. L., Aubeny, C. P. and Murff, J. D. (2001), “Toward the design of New Technologies for Deep-Water Anchorages,” Proceedings, Annual International Offshore and Polar Engineering Conference, Stavanger, Norway, in press
Smith, G. L. and Gilbert, R. B. (2001), “A Simplified Model of Spatial Variability to Evaluate Effects of Spatial Averaging on Foundation Capacity,” Proceedings, International Conference on Structural Safety and Reliability, Huntington Beach, California, in press
Gilbert, R. B., McBrayer, M. C. and Tang, W. H. (2000), “Statistical Considerations in Calibrating Performance Models with Field Data,” Proceedings of Performance Confirmation of Constructed Geotechnical Facilities, ASCE, GSP No. 94, Amherst, 307-321.
Gilbert, R. B. (2000), “Optimizing Investigation Programs for Offshore Platform Foundations – Effect of Geology on Axial Pile Capacity,” Proceedings, International Young Geotechnical Engineers Conference 2000, University of Southampton
Gambino, S. J. and Gilbert, R.B. (1999), “Modeling Spatial Variability in Pile Capacity for Reliability-Based Design,” Analysis, Design, Construction and Testing of Deep Foundations, Roesset Ed., ASCE Geotechnical Special Publication No. 88, 135-149.
Gilbert, R. B., Stong, T. J., Lang, J. T., Albrecht, R. S. and Dupin, R. M. (1999), “Optimizing Investigation Programs for Offshore Foundations – Effect of Geology on Axial Pile Capacity,” Proceedings, 2nd International Conf. on Seabed Geotechnics, IBC Ltd., London
Gilbert, R. B., Gambino, S. J. and Dupin, R. M. (1999), “Reliability-Based Approach for Foundation Design without Site-Specific Soil Borings,” Proceedings, Offshore Technology Conference, Houston, Texas, 631-640
Date: January 30, 2002
Project Name: Seafloor Characterization for Deepwater Production Systems
Task Order: 16169 Project Number: 58874
Principal Investigators: R.M. Gilbert
Estimated Completion Date: December, 2005
Project Description:
The goal of this research is to develop a methodology to optimize geotechnical investigation programs for deepwater foundations. Specific research objectives are:
1. Develop models describing spatial variability in foundation design parameters for different geologic profiles encountered in deepwater fields.
2. Relate uncertainty in foundation design parameters to partial safety or resistance factors required to achieve target reliability levels for different foundation types and loading conditions.
3. Quantify the added value of geologic and geophysical information in reducing uncertainty in foundation design parameters.
4. Quantify the added value of foundation installation information in reducing uncertainty in foundation design parameters.Progress:
1. Compiled data for 16 sites in the Gulf of Mexico and the North Sea.
2. Analyzed variability in foundation capacity across these fields.
3. Developing a Joint Industry Project to increase the amount of data available to calibrate models to predict foundation capacity.
4. Working with API project to quantify reliability of suction caissons and anchors.