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
Deepwater Anchors
OBJECTIVE: The original project objectives are to: (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.APPROACH: Analytical and numerical methods are being developed to predict: (1) the load capacity of suction caissons under general conditions of inclined loading, and (2) the installation trajectory and load capacity of vertically loaded drag embedment anchors. The techniques being developed are based on plastic limit analyses, with finite element analyses being used in the development and validation of the plastic limit formulations. The rationale for using the plastic limit formulation is that it can be implemented in a relatively simple spreadsheet or personal computer format, while maintaining a fairly high degree of theoretical rigor. Thus, plastic limit formulations provide a convenient framework for developing design tools accessible to practitioners.
DEPLOYMENT OF RESULTS: The formulation, validation, and parametric studies associated with the analytical and numerical models developed in this project will be presented in offshore technology conferences and peer-reviewed journals. Spreadsheet programs for predicting load capacity of suction caisson and vertically loaded plate anchors are being made available to practicing engineers.
PROJECT DURATION: 6 years
PROJECT PLAN FOR YEAR 6 (2004-2005):
Previous Results: Work during the 2003 -2004 year included:
1. Completion of a plastic limit model for predicting trajectory and load capacity of a drag embedment anchor.
2. Finite element studies supporting the development of a plastic limit drag embedment model. These finite element studies investigate soil resistance interaction relationships for different modes of anchor loading and the kinematics of motion of a drag embedment anchor.
3. Studies to investigate suction caisson behavior in cohesive soil deposits having non-homogeneous strength profiles.
4. Improvement of the user interface for the previously developed computer code for estimating suction caisson ultimate capacity under inclined loading conditions.Scope of Work for 2004-2005: Planned work for the 2004-2005 year includes:
1. Validation of the plastic limit drag embedment anchor model based on comparisons to alternative predictive methods.
2. Finite element simulations to support the validation of the simplified plastic limit model.
3. Disseminate spreadsheets for suction caissons and VLA’s to industry through OTRC.
4. Complete a final report on this projectAnticipated Results: Simplified analytical models for drag embedment anchors will be made available for practitioners. Model development and validation will be documented in the form of a final report, conference publications and peer-reviewed journal papers.
PRINCIPAL INVESTIGATOR (S) & OTHERS INVOLVED IN PROJECT:
PI(s) (TAMU): Aubeny, C.P and Murff, J.D.
Date: December, 2005
Project Title: Suction Caissons & Vertically Loaded Anchors
MMS Project: 362 TO Numbers: 16169/35980
PI: Charles Aubeny and Don Murff
COTR: S. Buffington
Estimated Completion Date: December 2005
Project Description: The project objectives are to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.
Progress: Model development and validation on SCA’s are essentially completed for this project. A PhD student has successfully defended his dissertation involving an upper bound plastic limit analysis of VLA trajectory and capacity; finalization of dissertation is anticipated by December 2005. Several papers disseminating the findings of the research were incorporated into the proceedings for the International Symposium for Offshore Geotechnics in September 2005.
Project completed, and draft final report issued to MMS.
Reports & Publications:
Kim, B.Y. (2005) Upper Bound Analysis for Drag Anchors in Soft Clay, PhD Dissertation, Texas A&M University, College Station, Texas.Murff, J.D., Randolph, M.F., Elkhatib, S., Kolk, H.J., Ruinen, R., Strom, P.J., and Thorne, C. (2005) “Vertically loaded plate anchors for deepwater applications,” Keynote lecture for presentation at International Symposium on Frontiers in Offshore Geotechnics, Perth, Australia.
Andersen, K.H., Murff, J.D. Randolph, M.F., Clukey, E., Jostad, H.P., Hansen, B. Aubeny, C., Sharma, P., Erbich, C., and Supachawarote, C. (2005) “Suction anchors for deepwater applications,” Keynote lecture for presentation at International Symposium on Frontiers in Offshore Geotechnics, Perth, Australia, September 2005.
Aubeny, C.P, Kim, B.M, and Murff, J.D. (2005) “Proposed upper bound analysis for drag embedment anchors, for publication in International Symposium on Frontiers in Offshore Geotechnics, Perth, Australia.
Anderson, K.H., Murff, J.D., and Randolph, M. (2004) Deepwater Anchor Design Practice, Final Year Report submitted to the American Petroleum Institute and the Deepstar JIP.
Aubeny, C.P. and Murff, J.D. (2003) “Simplified limit solutions for undrained capacity of suction anchors,” Deepwater Mooring Systems: Concepts, Design, Analysis, and Materials, Houston, pp76-90.
Aubeny, C.P., Han, S.W., and Murff, J.D. (2003) “Inclined load capacity of suction caisson anchors,” Intl. J. for Numerical and Analytical Methods in Geomechanics, Vol. 27, pp1235-1254.
Aubeny C.P. Han S.W.,and Murff, J.D. (2003) “Suction caisson capacity in anisotropic soil,” Intl. J. of Geomechanics, Vol. 3(4), pp225-235.
Aubeny, C.P., Han, S.W. and Murff, J.D. (2003) “Refined model for inclined load capacity of suction caissons,” 22nd International Conference on Offshore and Arctic Engineering, June 8-13, Cancun, Mexico, OMAE2003-37502.
Clukey, E.C., Aubeny, C.P. and Murff, J.D. (2003) “Comparison of analytical and centrifuge model tests for suction caissons subjected to combined loads,” 22nd International Conference on Offshore and Arctic Engineering, June 8-13, Cancun, Mexico, OMAE2003-37503.
Aubeny, C.P., Moon, S.K., and Murff, J.D. (2001) “Lateral undrained resistance of suction caisson anchors,” Intl. J. Offshore and Polar Engineering, Volume 11, No. 3, pp211-219.
Aubeny, C.P., Murff, J.D., and Roesset, J.M. (2001) “Geotechnical issues in deep and ultra deep waters,” Intl. J. of Geomechanics, September, Volume 1, Number 2, pp225-247.
Date: June 2005
Project Title: Suction Caissons & Vertically Loaded Anchors
MMS Project: 362 TO Numbers: 16169/35980
PI: Charles Aubeny and Don Murff
COTR: A. Konczvald
Estimated Completion Date: August 2005
Project Description: The project objectives are to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.
Progress: Model development and validation on SCA’s are essentially completed for this project. A PhD student is presently completing his dissertation involving an upper bound plastic limit analysis of VLA trajectory and capacity. Several papers disseminating the findings of the research will be presented at the International Symposium for Offshore Geotechnics in September 2005.
Reports & Publications:
Murff, J.D., Randolph, M.F., Elkhatib, S., Kolk, H.J., Ruinen, R., Strom, P.J., and Thorne, C. (2005) “Vertically loaded plate anchors for deepwater applications,” Keynote lecture for presentation at International Symposium on Frontiers in Offshore Geotechnics, Perth, Australia.
Andersen, K.H., Murff, J.D. Randolph, M.F., Clukey, E., Jostad, H.P., Hansen, B. Aubeny, C., Sharma, P., Erbich, C., and Supachawarote, C. (2005) “Suction anchors for deepwater applications,” Keynote lecture for presentation at International Symposium on Frontiers in Offshore Geotechnics, Perth, Australia, September 2005.
Aubeny, C.P, Kim, B.M, and Murff, J.D. (2005) “Proposed upper bound analysis for drag embedment anchors, for publication in International Symposium on Frontiers in Offshore Geotechnics, Perth, Australia.
Anderson, K.H., Murff, J.D., and Randolph, M. (2004) Deepwater Anchor Design Practice, Final Year Report submitted to the American Petroleum Institute and the Deepstar JIP.
Aubeny, C.P. and Murff, J.D. (2003) “Simplified limit solutions for undrained capacity of suction anchors,” Deepwater Mooring Systems: Concepts, Design, Analysis, and Materials, Houston, pp76-90.
Aubeny, C.P., Han, S.W., and Murff, J.D. (2003) “Inclined load capacity of suction caisson anchors,” Intl. J. for Numerical and Analytical Methods in Geomechanics, Vol. 27, pp1235-1254.
Aubeny C.P. Han S.W.,and Murff, J.D. (2003) “Suction caisson capacity in anisotropic soil,” Intl. J. of Geomechanics, Vol. 3(4), pp225-235.
Aubeny, C.P., Han, S.W. and Murff, J.D. (2003) “Refined model for inclined load capacity of suction caissons,” 22nd International Conference on Offshore and Arctic Engineering, June 8-13, Cancun, Mexico, OMAE2003-37502.
Clukey, E.C., Aubeny, C.P. and Murff, J.D. (2003) “Comparison of analytical and centrifuge model tests for suction caissons subjected to combined loads,” 22nd International Conference on Offshore and Arctic Engineering, June 8-13, Cancun, Mexico, OMAE2003-37503.
Aubeny, C.P., Moon, S.K., and Murff, J.D. (2001) “Lateral undrained resistance of suction caisson anchors,” Intl. J. Offshore and Polar Engineering, Volume 11, No. 3, pp211-219.
Aubeny, C.P., Murff, J.D., and Roesset, J.M. (2001) “Geotechnical issues in deep and ultra deep waters,” Intl. J. of Geomechanics, September, Volume 1, Number 2, pp225-247.
Date: December, 2004
Project Title: Suction Caissons & Vertically Loaded Anchors
MMS Project: 362 TO Numbers: 16169/35980
PI: Charles Aubeny and Don Murff
COTR: A. Konczvald
Estimated Completion Date: August 2005
Project Description: The project objectives are to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.
Progress: At present one PhD student is completing his dissertation involving an upper bound plastic limit analysis of VLA trajectory and capacity. The model is in the final stages of development. Several publications disseminating this work to practitioners are expected to stem from this work. Two such publications are in the final stages of preparation for submission to an upcoming conference on offshore geotechnics at the Center for Offshore Foundation Systems in Australia.
Model development and validation for SCA’s are essentially completed for this project.Reports & Publications:
Anderson, K.H., Murff, J.D., and Randolph, M. (2004) Deepwater Anchor Design Practice, Final Year Report submitted to the American Petroleum Institute and the Deepstar JIP.Aubeny, C.P. and Murff, J.D. (2003) “Simplified limit solutions for undrained capacity of suction anchors,” Deepwater Mooring Systems: Concepts, Design, Analysis, and Materials, October 2-3, Houston, pp76-90.
Aubeny, C.P., Han, S.W., and Murff, J.D. (2003) “Inclined load capacity of suction caisson anchors,” Intl. J. for Numerical and Analytical Methods in Geomechanics, Vol. 27, pp1235-1254.
Aubeny C.P. Han S.W.,and Murff, J.D. (2003) “Suction caisson capacity in anisotropic soil,” Intl. J. of Geomechanics, Vol. 3(4), pp225-235.
Aubeny, C.P., Han, S.W. and Murff, J.D. (2003) “Refined model for inclined load capacity of suction caissons,” 22nd International Conference on Offshore and Arctic Engineering, June 8-13, Cancun, Mexico, OMAE2003-37502.
Clukey, E.C., Aubeny, C.P. and Murff, J.D. (2003) “Comparison of analytical and centrifuge model tests for suction caissons subjected to combined loads,” 22nd International Conference on Offshore and Arctic Engineering, June 8-13, Cancun, Mexico, OMAE2003-37503.
Aubeny, C.P., Moon, S.K., and Murff, J.D. (2001) “Lateral undrained resistance of suction caisson anchors,” Intl. J. Offshore and Polar Engineering, Volume 11, No. 3, pp211-219.
Aubeny, C.P., Murff, J.D., and Roesset, J.M. (2001) “Geotechnical issues in deep and ultra deep waters,” Intl. J. of Geomechanics, September, Volume 1, Number 2, pp225-247.
Date: June 2004
Project Name: Deepwater Anchors
Project Number: 362 Task Order: 16169
Principal Investigators: Charles Aubeny and Don Murff
Estimated Completion Date: September 2005
Project Description:
The project objectives are to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.
Progress:
The plastic limit analysis model for suction anchors subjected to inclined loads was modified to permit analysis of general conditions of skin resistance. The refined model predictions compared well to centrifuge test data recently produced by C-Core under the sponsorship of BP-Amoco. The model refinement and the centrifuge test comparisons are documented in two papers that were presented at a conference sponsored by OMAE in July 2003. A spreadsheet incorporating the model refinements and improving the user interface was completed in draft and is being tested prior to release. The spreadsheet was used by Prof. Rauch and his students to make predictions of their model tests with excellent results. A suite of finite element analyses on suction caissons was completed for use in the API/DeepStar Project.
At present two PhD students are engaged in research involving plate anchor capacity. The first student is developing an upper bound plastic limit analysis (UBPLA) model for predicting drag embedment anchor trajectory and load capacity. This model is in the final stages of development and a submittal for publication of the model is anticipated within the next several months. Additional studies have been carried out to evaluate assumptions regarding soil resistance distribution on an anchor fluke. Updates of the model based on these studies should improve predictions of anchor installation behavior. The second PhD student is performing finite element simulations of loaded plate anchors to better understand load resistance interactions and kinematics of plate motions under general conditions of loading. The finite element simulations are being used to support the development and validation of the UBPLA model. A suite of analyses considering multiaxial loading has been completed for use in the API/DeepStar Project.
The above study is one of several related studies for a project on suction caissons and deepwater anchors being sponsored by the OTRC industry and MMS sponsors. In addition to these studies, a project sponsored by the API and DeepStar that was directed at defining and evaluating the state-of-the-art in deepwater anchor design has been completed and documented in a series of reports (9 volumes) The synergy between this project and the other studies has materially enhanced both projects.Reports & Publications:
Deepwater Anchor Design Practice, Final Year Report submitted to the American Petroleum Institute and the DeepStar JIP, 2004.
- Comparison of Analytical and Centrifuge Model Tests for Suction Caissons Subjected to Combined Load, accepted for publication in ASME Journal of Offshore Mechanics and Arctic Engineering, 2004.
- Simplified Limit Solutions for Undrained Capacity of Suction Caissons, presented at the International Symposium on Deepwater Mooring Systems: Concepts, Design, Analysis, and Materials, 2003.
- Refined Model for Inclined Load Capacity of Suction Caissons, Proceedings of OMAE’03, the 22nd International Conference on Offshore Mechanics and Arctic Engineering, 2003.
- Comparison of Analytical and Centrifuge Model Tests for Suction Caissons Subjected to Combined Load, Proceedings of OMAE’03, the 22nd International Conference on Offshore Mechanics and Arctic Engineering, 2003.
- Inclined Load Capacity of Suction Caissons, Intl. J. for Numerical and Analytical Methods in Geomechanics, 2003.
- Suction Caisson Capacity in Anisotropic Soil, International Journal of Geomechanics, 2003.
Date: December 2003
Project Name: Design Practice for Suction Caissons and VLA’s
TEES Project Number: 32588-5887F MMS Task Order: 16169 MMS Project Number: 362
Principal Investigators: Charles Aubeny and Don Murff
Estimated Completion: October 2004
Project Description:
The project objectives are to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.
Progress:
Suction Caissons The plastic limit analysis model for suction anchors subjected to inclined loads was modified to permit analysis of general conditions of skin resistance. The refined model predictions compared well to centrifuge test data recently produced by C-Core under the sponsorship of BP-Amoco. The model refinement and the centrifuge test comparisons are documented in two papers that were presented at a conference sponsored by OMAE in July 2003.A spreadsheet incorporating the model refinements and improving the user interface was completed in draft and is being tested prior to release. The spreadsheet has been used by Prof. Rauch and his students to make predictions of their model tests with excellent results.
A suite of finite element analyses on suction caissons was completed for use in the API/DeepStar Project.
Plate Anchors Two PhD students are engaged in research involving plate anchor capacity. The first student is developing an upper bound plastic limit analysis (UBPLA) model for predicting drag embedment anchor trajectory and load capacity. This model is in the final stages of development and a submittal for publication of the model is anticipated within the next several months. Additional studies have been carried out to evaluate assumptions regarding soil resistance distribution on an anchor fluke. Updates of the model based on these studies should improve predictions of anchor installation behavior.
The second PhD student is performing finite element simulations of loaded plate anchors to better understand load resistance interactions and kinematics of plate motions under general conditions of loading. The finite element simulations are being used to support the development and validation of the UBPLA model. A suite of analyses considering multiaxial loading has been completed for use in the API/DeepStar Project.
State-of-the-Art in Deepwater Anchors In addition to the above studies a series of reports (9 volumes) directed at defining and evaluating the state-of-the-art in deepwater anchor design is nearing completion. This project was sponsored by API and the DeepStar JIP but the synergy with the OTRC (Industry and MMS) sponsored projects has materially enhanced both projects.
Reports:
- Simplified Limit Solutions for Undrained Capacity of Suction Caissons, presented at the 2003 International Symposium on Deepwater Mooring Systems: Concepts, Design, Analysis, and Materials.
- Refined Model for Inclined Load Capacity of Suction Caissons, accepted for publication in the Proceedings of OMAE’03, the 22nd International Conference on Offshore Mechanics and Arctic Engineering.
- Comparison of Analytical and Centrifuge Model Tests for Suction Caissons Subjected to Combined Load, accepted for publication in the Proceedings of OMAE’03, the 22nd International Conference on Offshore Mechanics and Arctic Engineering.
- Suction Caisson Capacity in Anisotropic Soil, accepted for publication in the International Journal of Geomechanics, 2002.
- Deepwater Anchor Design Practice, First Year Report to be submitted to the American Petroleum Institute, 2001
- Inclined Load Capacity of Suction Caissons, tentatively accepted for the International Journal for Numerical and Analytical Methods in Geomechanics, 2002.
- Geotechnical Issues in Deep and Ultra Deep Waters, International Journal of Geomechanics, 2001.
- Lateral Undrained Resistance of Suction Caisson Anchors, International Society of Offshore and Polar Engineers, 2001.
Date: June, 2003
Project Name: Design Practices for Suction Caissons & VLA’s
Project Number: 32588-5887F Task Order: 16169
Principal Investigators: Charles Aubeny and Don Murff
Estimated Completion: October 2003
Project Description:
The project objectives are to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.Progress:
The plastic limit analysis model for suction anchors subjected to inclined loads was modified to permit analysis of general conditions of skin resistance. The refined model predictions compared well to centrifuge test data recently produced by C-Core under the sponsorship of BP-Amoco. The model refinement and the centrifuge test comparisons are documented in two papers that have been accepted for presentation at a conference sponsored by OMAE in July 2003.
At present two PhD students are engaged in research involving plate anchor capacity. The first student is developing an upper bound plastic limit analysis (UBPLA) model for predicting drag embedment anchor trajectory and load capacity. This model is in the final stages of development and a submittal for publication of the model is anticipated within the next several months. The second PhD student is performing finite element simulations of loaded plate anchors to better understand load resistance interactions and kinematics of plate motions under general conditions of loading. The finite element simulations are being used to support the development and validation of the UBPLA model.
Two additional graduate students are continuing the work on suction caisson anchors. One student is improving the interface for inclined load model to facilitate usage by practitioners. The second student is initiating studies on suction caisson behavior in stratified sediment profiles.Reports:
Refined Model for Inclined Load Capacity of Suction Caissons, accepted for publication in the Proceedings of OMAE’03, the 22nd International Conference on Offshore Mechanics and Arctic Engineering.Comparison of Analytical and Centrifuge Model Tests for Suction Caissons Subjected to Combined Load, accepted for publication in the Proceedings of OMAE’03, the 22nd International Conference on Offshore Mechanics and Arctic Engineering.
Suction Caisson Capacity in Anisotropic Soil, accepted for publication in the International Journal of Geomechanics, 2002.
Deepwater Anchor Design Practice, First Year Report submitted to the American Petroleum Institute, 2001.
Inclined Load Capacity of Suction Caissons, tentatively accepted for the International Journal for Numerical and Analytical Methods in Geomechanics, 2002.
Geotechnical Issues in Deep and Ultra Deep Waters, International Journal of Geomechanics, 2001.
Lateral Undrained Resistance of Suction Caisson Anchors, International Society of Offshore and Polar Engineers, 2001.
Date: November, 2002
Project Name: Design Practices for Suction Caissons & VLA’s
Project Number: 32588-5887F CE & 32518-5887FM CE Task Order: 16169
Principal Investigators: Charles Aubeny and Don Murff
Estimated Completion: October 2003
Project Description:
The project objectives are to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.Progress:
The laterally loaded suction caisson model developed in a previous reporting period has been extended to include vertical components of loading; a journal article concerning this work has been submitted for publication and reviewed. A study of suction anchor capacity for anisotropic clay soils has also been completed. A paper documenting this work has been accepted for publication.A report documenting available performance prediction methods for SCA’s and VLA’s was prepared in conjunction with API sponsored research and completed in the last quarter of 2001. Phase two of this project has been initiated. In this effort actual and hypothetical test data have been selected to use in an industry prediction exercise. This study will be used to assess bias and uncertainty in current prediction methods for installation and capacity of SCA’s and VLA’s and ultimately to formulate design guidelines for API Recommended Practices.
A plastic limit analysis of embedment anchors that can overcome some of the limitations of existing methods has been formulated. A new PhD student has made significant progress in its implementation. Recent developments include a strategy for predicting anchor trajectory during installation. Another PhD student is conducting finite element analyses of anchor plates under vertical and inclined loads. Results of this study will be used to develop load interaction relationships for incorporation into the trajectory prediction.
A master’s thesis reviewing and evaluating existing prediction methods for drag embedment and vertically loaded anchors has been completed. A doctoral thesis applying plastic limit analysis methods for evaluation of suction caisson load capacity has also been completed.
Reports:
Suction Caisson Capacity in Anisotropic Soil, accepted for publication in the International Journal of Geomechanics, 2002.Deepwater Anchor Design Practice, First Year Report to be submitted to the American Petroleum Institute, 2001.
Inclined Load Capacity of Suction Caissons, tentatively accepted for the International Journal for Numerical and Analytical Methods in Geomechanics, 2002.
Geotechnical Issues in Deep and Ultra Deep Waters, International Journal of Geomechanics, 2001.
Lateral Undrained Resistance of Suction Caisson Anchors, International Society of Offshore and Polar Engineers, 2001.
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Date of Summary: May 2002
Project Name: Design Practices for Suction Caissons & VLA’s
Task Order: 16169 Project Number: 5887F
Principal Investigators: Charles Aubeny and Don Murff
Estimated Completion Date: October 2002
Project Description:
The project objectives are to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.Progress:
The laterally loaded suction caisson model developed in a previous reporting period has been extended to include vertical components of loading; a journal article concerning this work has been submitted for publication and reviewed. A study of suction anchor capacity for anisotropic clay soils has also been completed. A paper documenting this work has been submitted for publication and reviewed. Revisions responding to reviewer comments are in progress for both papers.A report documenting available performance prediction methods for SCA’s and VLA’s was prepared in conjunction with API sponsored research and completed in the last quarter of 2001. A plastic limit analysis of embedment anchors that can overcome some of the limitations of existing methods has been formulated and development of the method is in progress. Toward this end, a PhD student is conducting finite element analyses of anchor plates under vertical and inclined loads.
A master’s thesis reviewing and evaluating existing prediction methods for drag embedment and vertically loaded anchors has been successfully defended and final revisions are in progress. A doctoral thesis applying plastic limit analysis methods for evaluation of suction caisson load capacity is scheduled for completion in August 2002.
Reports:
Suction Caisson Capacity in Anisotropic Soil, tentatively approved for publication in the International Journal of Geomechanics, 2002.Deepwater Anchor Design Practice, First Year Report to be submitted to the American Petroleum Institute, 2001.
Inclined Load Capacity of Suction Caissons, Submitted to the International Journal for Numerical and Analytical Methods in Geomechanics, 2002.
Geotechnical Issues in Deep and Ultra Deep Waters, International Journal of Geomechanics, 2001.
Lateral Undrained Resistance of Suction Caisson Anchors, International Society of Offshore and Polar Engineers, 2001
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Date of Summary: December 1, 2001
Project Name: Design Practices for Suction Caissons & VLA’s
Task Order: 16169 Project Number: 5887F
Principal Investigators: Charles Aubeny and Don Murff
Estimated Completion Date: October 2002
Project Description:
The project is to (1) determine the currently available best practices for analysis and design of suction caisson anchors (SCA’s) and vertically loaded anchors (VLA’s) including drag embedment anchors, and (2) effect improvements in the installation and capacity predictions for SCA’s and VLA’s.Progress:
The laterally loaded suction caisson model developed in a previous reporting period has been extended to include vertical components of loading; a journal article concerning this work has been submitted. A study of suction anchor capacity for anisotropic clay soils has also been completed. A paper documenting this work is in final draft and will be submitted for publication shortly.A report documenting available performance prediction methods for drag embedment anchors is being prepared and should be completed in the first quarter 2002. A plastic limit analysis of embedment anchors that can overcome some of the limitations of existing methods has been formulated and a proposal to develop and calibrate this method has been submitted to NSF.
A final draft of a report documenting the state-of-the-art for deepwater anchor systems has been completed. This report includes a comprehensive database of actual applications and experiments for suction caissons and vertically loaded drag embedment anchors in clay soils. The primary sponsor of this work is API but the work is fundamental in meeting overall research objectives in the deepwater anchor area.
Reports & Publications:
Deepwater Anchor Design Practice, First Year Report to be submitted to the American Petroleum Institute, 2001.Inclined Load capacity of Suction Caissons, Submitted to the International Journal for Numerical and Analytical Methods in Geomechanics, 2001.
Geotechnical Issues in Deep and Ultra Deep Waters, International Journal of Geomechanics, 2001.
Lateral Undrained Resistance of Suction Caisson Anchors, International Society of Offshore and Polar Engineers, 2001.