1、 Guidance Notes on Design and Installation of Dynamically Installed Piles GUIDANCE NOTES ON DESIGN AND INSTALLATION OF DYNAMICALLY INSTALLED PILES DECEMBER 2017 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 2017 American Bureau of Shipping. All rights r
2、eserved. ABS Plaza 16855 Northchase Drive Houston, TX 77060 USA Foreword Foreword (1 December 2017) These Guidance Notes provide ABS recommendations for the design and installation of dynamically installed piles for offshore service. Included in these Guidance Notes are methodologies for the geotech
3、nical design and structural assessment of dynamically installed piles. Recommendations in these Guidance Notes are based on finite element analysis using appropriate soil modeling and simulation of soil-pile interaction. Alternatively, other approaches that can be proven to produce at least an equiv
4、alent level of safety will also be considered. These Guidance Notes are applicable to the design of dynamically installed piles, as a component of taut, semi-taut, or catenary mooring systems. The December 2017 edition incorporates a new Appendix 4, “Methodology to Calculate the Anchor Reverse Caten
5、ary Line”. These Guidance Notes become effective on the first day of the month of publication. Users are advised to check periodically on the ABS website www.eagle.org to verify that this version of these Guidance Notes is the most current. We welcome your feedback. Comments or suggestions can be se
6、nt electronically by email to rsdeagle.org. Terms of Use The information presented herein is intended solely to assist the reader in the methodologies and/or techniques discussed. These Guidance Notes do not and cannot replace the analysis and/or advice of a qualified professional. It is the respons
7、ibility of the reader to perform their own assessment and obtain professional advice. Information contained herein is considered to be pertinent at the time of publication, but may be invalidated as a result of subsequent legislations, regulations, standards, methods, and/or more updated information
8、 and the reader assumes full responsibility for compliance. This publication may not be copied or redistributed in part or in whole without prior written consent from ABS. ii ABSGUIDANCE NOTES ON DESIGN AND INSTALLATION OF DYNAMICALLY INSTALLED PILES .2017 Table of Contents GUIDANCE NOTES ON DESIGN
9、AND INSTALLATION OF DYNAMICALLY INSTALLED PILES CONTENTS SECTION 1 General 1 1 Background . 1 3 Scope and Application 1 5 Submission of Documents 1 5.1 Plans . 1 5.3 Reports 1 SECTION 2 Site Investigations . 2 1 General . 2 3 Desk Study 2 5 Geophysical Surveys 3 7 Geotechnical Surveys . 3 TABLE 1 Ba
10、sic Soil Parameters . 4 SECTION 3 Geotechnical Design 5 1 Introduction . 5 3 Design Methodology . 5 3.1 Embedment Depth Prediction in Cohesive Soil . 5 3.3 Holding Capacity Prediction 7 5 Estimation of Pile Capacity in Cohesive Soil 7 5.1 Axial Pile Capacity . 7 5.3 Lateral Pile Capacity . 7 7 Numer
11、ical Modeling 8 7.1 General 8 7.3 Finite Element Model . 9 7.5 Soil-Pile Interaction . 10 7.7 Load Steps 10 7.9 Acceptance Criteria for Ultimate Capacity . 10 9 Set-Up of Pile Capacity in Normally Consolidated Clay . 12 9.1 Set-Up Effect . 12 9.3 Short-Term and Long-Term Pile Capacity in Cohesive So
12、il 13 ABSGUIDANCE NOTES ON DESIGN AND INSTALLATION OF DYNAMICALLY INSTALLED PILES .2017 iii FIGURE 1 Illustration of Critical Mooring Load Direction from Plan View 8 FIGURE 2 FE Model Dimensions . 9 FIGURE 3 Example of Ultimate Force for Asymptotic Analysis Results 11 FIGURE 4 Example of Ultimate Fo
13、rce for Non-Asymptotic Analysis Results 11 FIGURE 5 Example of Ultimate Holding Capacity Analysis Results 12 FIGURE 6 Regain of Normalized Pile Capacity with Consolidation Time 13 SECTION 4 Structural Assessments 14 1 General . 14 3 Structural Model 14 5 Element Types 14 7 Loads 14 9 Fatigue and Yie
14、lding Check 14 FIGURE 1 Direction of Pile Top Force to Produce Maximum Stress in a Fin 15 SECTION 5 Installation Recommendations 16 1 General . 16 3 Installation Procedures Report and Records 16 5 Pre-Installation Verification . 16 7 Verification of Pile Installation . 17 APPENDIX 1 Commentary on th
15、e Calculation of Pile Embedment Depth in Cohesive Soil 18 1 General . 18 3 Procedure 18 5 Example of Determining Pile Embedment Depth . 20 5.1 Pile Parameters . 20 5.3 Soil Parameters . 20 5.5 Embedment Assessment . 20 TABLE 1 Pile Parameters . 20 TABLE 2 Soil Parameters . 20 FIGURE 1 Flowchart for
16、Procedure on Determining Pile Embedment Depth . 19 FIGURE 2 Penetration Resistance Profile 21 FIGURE 3 Strain Rate Function Rf vs Embedment Depth at Pile Tip . 21 FIGURE 4 Pile Velocity Profiles vs Embedment Depth at Pile Tip . 22 iv ABSGUIDANCE NOTES ON DESIGN AND INSTALLATION OF DYNAMICALLY INSTAL
17、LED PILES .2017 APPENDIX 2 Cyclic Loading Effect . 23 1 Background . 23 3 Cyclic Shear Strength . 23 5 Procedure to Calculate Cyclic Shear Strength . 24 5.1 Design Storm History 24 5.3 Equivalent Number of Cycles to Failure 25 5.5 Cyclic Contour Diagram. 25 5.7 Recommended Procedure . 26 FIGURE 1 Ty
18、pical Cyclic Shear Stress 23 FIGURE 2 Example of Transformation of Cyclic Loading History to Constant Cyclic Parcels 25 FIGURE 3 Contour Diagram Showing Number of Cycles to Failure as a Function of Normalized Average and Cyclic Shear Stresses 26 APPENDIX 3 Commentary on Acceptance Criteria . 27 1 Ge
19、neral . 27 3 Factor of Safety for Pile Holding Capacity 27 5 Acceptance Criteria for Yielding . 27 5.1 General 27 5.3 Yielding 27 5.5 Allowable Yielding Stresses 28 APPENDIX 4 Methodology to Calculate the Anchor Reverse Catenary Line 29 1 General . 29 3 Equilibrium Equations of Embedded Anchor Line
20、30 5 Simplified Solution for the Mooring Catenary Line 31 7 Description of Procedure 33 TABLE 1 Effective Surface and Bearing Area for Anchor Line 31 FIGURE 1 General Arrangement of Anchor Line . 29 FIGURE 2 Force Equilibrium of Anchor Line Element . 30 FIGURE 3 Soil Strength Adjustment to Account f
21、or Anchor Line Weight . 33 APPENDIX 5 References 34 ABSGUIDANCE NOTES ON DESIGN AND INSTALLATION OF DYNAMICALLY INSTALLED PILES .2017 v This Page Intentionally Left Blank Section 1: General SECTION 1 General 1 Background Dynamically installed piles are finned piles designed to be released from a hei
22、ght of 20-100 m above the seabed and reach velocities of 20-35 m/s at the seabed before self-embedment. They may be stabilized with multiple fins at the trailing edge. Tip penetration is expected to be two to three times the pile length and holding capacity after consolidation is expected in the ran
23、ge three to six times the pile weight. The main purpose of these Guidance Notes is to provide recommendations for the design and installation of a dynamically installed pile for taut, semi-taut or catenary mooring systems. The design and installation of dynamically installed piles are to be based on
24、 all applicable requirements of the ABS Rules for Building and Classing Offshore Installations (OI Rules), the ABS Rules for Building and Classing Floating Production Installations (FPI Rules), and the ABS Rules for Building and Classing Mobile Offshore Drilling Units (MODU Rules). 3 Scope and Appli
25、cation These Guidance Notes covers the geotechnical design, structural assessment and installation of a dynamically installed pile as a component of taut, semi-taut, or catenary mooring systems. 5 Submission of Documents The design documentation to be submitted should include the reports, calculatio
26、ns, plans and other documentation necessary to verify the adequacy of the foundation and structure. The extensiveness of the submitted documentation should reflect the uniqueness of the pile design and its application. 5.1 Plans Plans showing the scantlings, arrangements, specification for material,
27、 welding and fabrication, as well as construction details of the piles structure should be submitted and approved before the work of construction is commenced. These plans are to indicate clearly the details of welding, welding consumables, mass, and vertical center of gravity of the pile, etc. 5.3
28、Reports Reports indicating the soil conditions, holding capacity verification, and structural behavior should be submitted to ABS for review. In general, the following documents should be submitted for review, reference, and file: Site investigation reports including complete geophysical/geological/
29、geotechnical reports as well as an integration/interpretation report. Geotechnical design report to evaluate the adequacy of the holding capacity of the pile. Pile calculation documents should provide minimum penetration and maximum allowable inclinations of a pile from the vertical axis. After pile
30、 installation, if significant deviation is found, this report should be updated to verify the adequacy of the pile for the as-installed condition. Structural design report to evaluate the adequacy of the pile structure and the mooring padeye. Installation procedures and report for piles, including t
31、he design and final coordinates for pile installation, design and recovered monitoring data for pile penetration depth, orientation angle with vertical and azimuth angles of fins, when applicable. If the reference site is within a seismic zone, the site specific seismic hazard report should be submi
32、tted. ABSGUIDANCE NOTES ON DESIGN AND INSTALLATION OF DYNAMICALLY INSTALLED PILES .2017 1 Section 2: Site Investigations SECTION 2 Site Investigations 1 General The soil investigation should satisfy the requirements given in 3/6.3 of the ABS Rules for Building and Classing Offshore Installations (OI
33、 Rules). It is recommended that a high-quality, high-resolution geophysical survey be performed over the entire areal extent of the foundation. It is important that the geophysical and geotechnical components are planned together as integrated parts of the same investigation. Such an integrated stud
34、y can then serve as a guide to develop a scope of work for the vertical and horizontal extent of the final geotechnical investigation and to aid in the interpretation of the acquired geotechnical data. The sequence for the investigation program should be: Desk study Topographical and geophysical sur
35、vey Geotechnical survey and laboratory testing Additional geophysical and/or geotechnical surveys and/or laboratory testing as required Depending on the size of a project and/or the complexity of the geotechnical context and associated risks (geohazards), additional intermediate stages may be necess
36、ary. The soil investigation for a dynamically installed pile should give the basis for a geotechnical design comprising evaluation of: Pile embedment depth Ultimate holding capacity Structural adequacy in term of strength and fatigue resistance 3 Desk Study The desk study assembles existing data for
37、 preliminary site assessment and will formulate requirements for subsequent geophysical and geotechnical investigations. The desk study should include a review of all sources of appropriate information, collect and evaluate all available relevant data for the site including: Bathymetric information
38、Geological information Information and records of seismic activity Existing geotechnical data and information Previous experience with foundations in the area Regional meteorological and oceanographic data A desk study alone is not sufficient for detailed engineering purposes, but it should be suffi
39、cient for conceptual engineering to move forward in a focused manner and provide the basis upon which to design and plan subsequent site investigation work. 2 ABSGUIDANCE NOTES ON DESIGN AND INSTALLATION OF DYNAMICALLY INSTALLED PILES .2017 Section 2 Site Investigations 5 Geophysical Surveys Geophys
40、ical investigation can provide information about soil stratigraphy, local soil condition and evidence of geological features. The survey area should cover the full extent of the pile spread. The areal extent of soil layers can sometimes be mapped if good correspondence is established between the soi
41、l boring and in-situ test information and the results from the seabed surveys. Site specific, high-resolution geophysical information of a regional character obtained from seafloor and sub-bottom surveys at or near the project site should be submitted for review. The types of equipment for performin
42、g geophysical investigation can include the following: Echo sounder or swath bathymetric system for water depth and seafloor morphology. Sub-bottom profiler for structural features within the near-surface sediments. Side-scan sonar for seafloor features and seafloor reflectivity. Seismic sources for
43、 the structure to deeper depths up to approximately 100 m below the seafloor. The minimum depth of seismic profile should be the anticipated penetration depth plus a zone of influence of about ten times the equivalent pile diameter. The Equivalent Pile Diameter (EPD) is the diameter of a circle that
44、 circumscribes the pile structure including fins and shaft. Direct observation of the seafloor using a remotely operated vehicle (ROV) or manned submersible. 7 Geotechnical Surveys The geotechnical evaluation includes sampling for soil classification and engineering property testing, and in-situ soi
45、l profiling and strength testing. To establish the soil characteristics at the foundation locations, at least one boring or probing should be taken at pile cluster locations to a depth of the anticipated penetration depth plus a zone of influence of 15.2 m. Additional bore holes may be needed if sig
46、nificant discontinuities of the soil characteristics are verified, from cluster to cluster. If the foundation location is at a significant distance from the boring/probing location, additional verification boring/probing may be needed to validate the extrapolated data. In deep water, the relief of h
47、ydrostatic pore pressure and its resulting effect on any dissolved gases can produce soil properties significantly different from in-situ conditions. Because of these effects, in-situ testing is encouraged as it may provide a more reliable estimate of soil parameters with less sample disturbance. Ty
48、pical tools used include the remote vane, the piezoprobe, PCPT (piezocone penetrometer tests), T-bar or ball penetrometer, etc. If the soil investigation is performed primarily using PCPT, it is recommended that at least one boring with sampling be taken to properly calibrate the PCPT results. This
49、boring/core should be taken at one of the PCPT locations. The sampling interval should not exceed 1.0-1.5 m. The soil parameters for pile design will require high quality sampling in combination with advanced laboratory testing and correlations with in-situ test results. Consideration should be given to the performance of permeability and consolidation tests in order to assess set-up effects and capacity consideration for the dynamically installed pile. The site investigation and laboratory testing program should provide the information needed
