ISO PHASE 2 BENCHMARKING ISO (DIS) COMPARISON OF REVISED GEOTECHNICAL CLAUSES REPORT WITH ORIGINAL CLAUSES AND SNAME

Transcription

1 Noble House 39 Tabernacle Street London EC2A 4AA Phone Fax REPORT ISO PHASE 2 BENCHMARKING COMPARISON OF REVISED GEOTECHNICAL CLAUSES WITH ORIGINAL CLAUSES AND SNAME Report No: L25336, Rev, Dated Addendum to Reports L25217 and L25316 Distribution: ISO Committee Company: ABS Attn: Mr John Stiff Attn: W/S No: CTR 2 File: l iso additional geotechnical investigation.doc Noble Denton Consultants Ltd trading as GL Noble Denton Registered in England No Registered Office: Noble House, 39 Tabernacle Street, London, EC2A 4AA, UK

2 REVISION DETAILS Revision Date Description Author Checker Approver 29 th Nov 21 Draft for Internal Review ARM DHE MJRH 1 3 th Nov 21 Initial Issue to ISO committee for comment DHE ARM RWPS DESCRIPTION OF CHANGES Revision Section Change INSERTED DOCUMENT/FILE REGISTER Path and Filename Details of File Page 2 - of 36

3 CONTENTS SECTION PAGE 1 SCOPE OF WORK INTRODUCTION SCOPE OF WORK 6 2 GEOTECHNICAL THEORY GENERAL 8 3 FOOTING REACTIONS FOOTING REACTIONS FROM SUPER GORILLA ANALYSIS FOOTING REACTIONS FROM KFELS MOD B ANALYSIS ADDITIONAL INTERESTING FOOTING REACTIONS 1 4 V-H BEARING CAPACITY ENVELOPES AND FOUNDATION UTILISATIONS V-H BEARING CAPACITY ENVELOPES FOUNDATION UTILISATIONS STEP 3A ADDITIONAL SETTLEMENT CALCULATIONS 22 5 ANALYSIS OF THE RESULTS NEW ISO VS OLD ISO NEW ISO VS SNAME SAND FOUNDATIONS 27 6 CONCLUSIONS 33 REFERENCES 36 Page 3 - of 36

4 FIGURES Figure 1: Figure 2: Nov 21 Revised ISO V-H Envelope and Footing Reactions for Super Gorilla Unit 12 Original Dec 29 DIS ISO V-H Envelope and Footing Reactions for Super Gorilla unit 13 Figure 3: SNAME V-H Envelope for Super Gorilla with footing reactions from ISO analyses 14 Figure 4: Nov 21 Revised ISO V-H Envelope and Footing Reactions for KFELS B Class 15 Figure 5: Figure 6: Original Dec 29 DIS ISO V-H Envelope and Footing Reactions for KFELS B Class 16 SNAME V-H Envelope for KFELS B Class with footing reactions from ISO analyses 17 Figure 7: Example Vertical-Horizontal Capacity Envelope Showing Bearing Capacity Check 18 Figure 8: Example Vertical-Horizontal Capacity Envelope showing Sliding Capacity Check 19 Figure 9: Comparison of New ISO with Old ISO Bearing Capacity and Sliding Envelopes - Super Gorilla 23 Figure 1: Comparison of New ISO with Old ISO Bearing Capacity and Sliding Envelopes - KFELS B Class 23 Figure 11: Figure 12: Comparison of New ISO with SNAME Bearing Capacity and Sliding Envelopes for Super Gorilla unit (SNAME shifted for backfill and spudcan soil buoyancy) 25 Comparison of New ISO with SNAME Bearing Capacity and Sliding Envelopes for KFELS B Class unit (SNAME shifted for backfill and spudcan soil buoyancy). 25 Figure 13: ISO DIS V-H Envelope for Super Gorilla with footing reactions from ISO analyses 29 Figure 14: Figure 15: Figure 16: SNAME V-H Envelope for Super Gorilla with footing reactions from SNAME analyses 3 ISO DIS V-H Envelope for KFELS B Class with footing reactions from ISO analyses 31 SNAME V-H Envelope for KFELS B Class with footing reactions from SNAME analyses 32 Page 4 - of 36

5 TABLES Table 2-1 Footing Reactions 8 Table 3-1 Footing Reactions 9 Table 3-2 Footing Reactions 9 Table 3-3 Footing Reactions 1 Table 4-1 Bearing Capacity Utilisations for Super Gorilla 2 Table 4-2 Bearing Capacity Utilisations for KFELS B Class 21 Table 4-3 Additional Settlement for Super Gorilla unit 22 Table 4-4 Additional Settlement for KFELS B Class unit 22 Table 5-1 Final assessment results for the Super Gorilla 28 Table 5-2 Final assessment results for the KFELS B-Class 28 Page 5 - of 36

6 1 SCOPE OF WORK 1.1 INTRODUCTION GL Noble Denton has been instructed by ABS, on behalf of the ISO benchmarking committee, to carry out the phase 2 benchmarking of the ISO Petroleum and natural gas industries - Site-specific assessment of mobile offshore units - Part 1: Jack-Ups (Draft Industry Standard) (ISO) (Ref [2]) which has been developed from SNAME bulletin 5-5A (Ref [1]) Following the completion of the benchmarking analysis GL Noble Denton has been instructed by ABS, on behalf of the ISO benchmarking committee to carry out additional foundation bearing capacity checks based on revised Clauses 9 and A.9 of the ISO document issued in November 21. The revisions to these Clauses have been made since publication of the version of the DIS document issued in December 29 for the original benchmarking study This document shows a comparison between the geotechnical utilisations obtained using the revised ISO clauses, the original ISO DIS clauses and using the SNAME methodology described in Ref [1] This report should be considered as an addendum to the original GL Noble Denton benchmarking reports L25217 and L25316 (Refs. [3] and [4]). 1.2 SCOPE OF WORK The purpose of this work is to provide a comparison between the geotechnical utilisations obtained using the revised ISO clauses, the original benchmarked ISO clauses and the SNAME methodology described in SNAME bulletin 5-5A Rev 3 (Ref [1]) The footing reactions for this assessment have been taken from the benchmarking analysis of the Super Gorilla, as reported in L25217 (Ref. [3]), and the KFELS Mod V B as reported in L25316 (Ref. [4]), with additional realistic footing reactions added for the purposes of the comparison We have not compared the differences in utilisations for the sand foundation case as the only differences between the DIS and revised version of the ISO were a change in the origin used for determining the utilisations and constructing the factored V-H bearing capacity envelope that amounted to,3% of the preload footing reaction and hence would have negligible effect upon the results obtained. The resistance factor used for a partially penetrated spudcan in sand has not changed in the November 21 revision The deliverables include a report that details the findings of the study. Specific items that are reported include: Executive Summary; Geotechnical Theory; Footing reactions used for the comparison; Page 6 - of 36

7 Plots of the V-H envelope with footing reactions following the revised ISO document; Plots of the V-H envelope with footing reactions following the benchmarked ISO DIS; Plots of the V-H envelope with footing reactions following the SNAME methodology; Tables of utilisations comparing the three methodologies; Comments, discussion and analysis of the results; Conclusions which can be drawn from the comparisons. Page 7 - of 36

8 2 GEOTECHNICAL THEORY 2.1 GENERAL This report compares the results obtained using the Step 2a foundation checks from SNAME, the original DIS (December 29) and revised ISO DIS of November 21. The changes to the foundation check in the ISO DIS were made in order to ensure an appropriate origin for factoring the V-H bearing capacity envelope that does not factor the weight of backfill and spudcan buoyancy, and to apply a consistent resistance factor regardless of whether the foundation is partially or fully penetrated into the seabed The formulation for calculating the unfactored bearing capacity envelope and the formulation for calculating the origin used to define the foundation utilisations has not been revised. It is, however, noted that for fully penetrated spudcans the origin used to define the foundation utilisations will have changed as a consequence of the change of the resistance factor from 1,15 to 1, The revisions are summarised below in Table 2-1. Table 2-1 Footing Reactions Utilisation Origin (F H,F V ) ORG Bearing capacity resistance factor, γ R,VH Partial Penetration Fully penetrated Origin used for construction of factored V-H envelope SNAME (,SWL 1 ) (,) 2 ISO DIS (,Q V /2γ R,VH ) (,) Revised ISO (,Q V /2γ R,VH ) 1.1 (,W BF,O -B S ) 1 SWL = Stillwater footing reaction 2 This origin is adopted by GLND for SNAME foundation checks. We are aware that some consultants choose a different interpretation of the SNAME Recommended Practice in this respect. 3 We note that there is an inconsistency in the DIS version whereby the origin is also referred to as (,Q V /2), which we have presumed to be a typographic error. Page 8 - of 36

9 3 FOOTING REACTIONS 3.1 FOOTING REACTIONS FROM SUPER GORILLA ANALYSIS The footing reactions calculated by GL Noble Denton for the Super Gorilla during the benchmarking analysis are presented below. Note, the weight of backfill (44317 kn) is included in the vertical reactions. Table 3-1 Footing Reactions Storm Heading Leg Maximum Hull Weight Minimum Hull Weight F H (kn) F V (kn) F M (kn-m) F H (kn) F V (kn) F M (kn-m) Bow Port Starboard Bow Port Starboard Bow Port Starboard FOOTING REACTIONS FROM KFELS MOD B ANALYSIS The footing reactions calculated by GL Noble Denton for the KFELS B Class during the benchmarking analysis are presented below. Note, the weight of backfill (2421 kn) is included in the vertical reactions. Table 3-2 Footing Reactions Storm Heading Leg Maximum Hull Weight Minimum Hull Weight F H (kn) F V (kn) F M (kn-m) F H (kn) F V (kn) F M (kn-m) Bow Port Starboard Bow Port Starboard Bow Port Starboard Page 9 - of 36

10 3.3 ADDITIONAL INTERESTING FOOTING REACTIONS Additional footing reactions are proposed corresponding to utilisations of 1, according to each method in order to compare the utilisations obtained using each methodology. These comprise two points on the factored V-H envelope at low and high horizontal load components, and one point on the factored sliding line, as shown in Figure 1 to Figure 6. Sets of values are proposed for both rig types. Note, the weight of backfill is included in these vertical reactions; the weight of backfill is and 2421 kn for the Super Gorilla and KFELS units respectively. Table 3-3 Footing Reactions New ISO (Nov 21) Old ISO DIS SNAME Load case On V-H Envelope small F H On V-H Envelope large F H On Sliding Envelope On V-H Envelope small F H On V-H Envelope large F H On Sliding Envelope On V-H Envelope small F H On V-H Envelope large F H On Sliding Envelope Super Gorilla KFELS B Class F H (kn) F V (kn) F H (kn) F V (kn) Page 1 - of 36

11 4 V-H BEARING CAPACITY ENVELOPES AND FOUNDATION UTILISATIONS 4.1 V-H BEARING CAPACITY ENVELOPES Figure 1, Figure 2 and Figure 3 overleaf present the footing reactions calculated for the Super Gorilla unit from the ISO analyses plotted onto the yield envelopes derived using the revised ISO DIS methodology, the original benchmarked ISO DIS methodology and the SNAME methodology. Note that the footing reactions plotted against the SNAME envelope exclude the weight of soil backfill in order to be comparable with the bearing capacity envelope Figure 4, Figure 5, Figure 6 present the same plots for the KFELS Mod V B Class analyses. Page 11 - of 36

12 Generic Super Gorilla at Generic clay location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE Location Details Generic clay location for ISO Phase 2 Benchmarking Coordinates : N/A N, N/A E Depth of water : 85. m (279 ft) Spudcan Geometry Jack-up Unit Details Generic Super Gorilla Design : Super Gorilla Calculated Spudcan Reactions at Seabed Level Preload reaction V Lo : 15,876 tonnes (35,1 kips) 15,87635,1 Stillwater reaction : 8,582 tonnes (18,92 kips) 8,582 18,92 Parameters Used in V-H Calculations Expected spudcan tip penetration : 42.2 m (138 ft) 138 Maximum spudcan contact area, A : m 2 (2,618 sq.ft) 2,618 Laterally projected spudcan area, As : 99.4 m 2 (1,7 sq.ft) 1,7 Steel/sand interaction factor, δ : N.A. o. c u at maximum bearing area, c uo : 59 kpa (1,232 lb/sq.ft) 1,232 c u at spudcan tip, c ut : 61 kpa (1,274 lb/sq.ft) 1,274 Preload resistance factor, γ R,PRE : 1.1 Partial resistance factor horizontal capacity, γ R,Hfc : 1.56 Partial resistance factor foundation capacity, γ R,VH : 1.1 } Revised ISO Nov 21 V-H Bearing Capacity Envelope Fh (kips) Maximum Hull Weight Minimum Hull Weight 2 SNAME UC=1, Unfactored V-H capacity Old ISO UC=1, Factored V-H capacity New ISO UC=1, 5 4 Fv (tonnes) Stillwater spudcan reaction (triangle) Origin used for utilisation checks (diamond),5q V /γ R,VH Fh (tonnes) spud_pen ISOv W.S Calc: DHE Appvd: MJRH Date: 27-Nov-1 Factored sliding capacity Unfactored sliding capacity Fv (kips) Figure 1: Nov 21 Revised ISO V-H Envelope and Footing Reactions for Super Gorilla Unit Page 12 - of 36

13 Generic Super Gorilla at Generic clay location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE Location Details Generic clay location for ISO Phase 2 Benchmarking Coordinates : N/A N, N/A E Depth of water : 85. m (279 ft) Spudcan Geometry Jack-up Unit Details Generic Super Gorilla Design : Super Gorilla Calculated Spudcan Reactions at Seabed Level Preload reaction V Lo : 15,876 tonnes (35,1 kips) 15,87635,1 Stillwater reaction : 8,582 tonnes (18,92 kips) 8,582 18,92 Parameters Used in V-H Calculations Expected spudcan tip penetration : 42.2 m (138 ft) 138 Maximum spudcan contact area, A : m 2 (2,618 sq.ft) 2,618 Laterally projected spudcan area, As : 99.4 m 2 (1,7 sq.ft) 1,7 Steel/sand interaction factor, δ : N.A. o. c u at maximum bearing area, c uo : 59 kpa (1,232 lb/sq.ft) 1,232 c u at spudcan tip, c ut : 61 kpa (1,274 lb/sq.ft) 1,274 Preload resistance factor, γ R,PRE : 1.1 Partial resistance factor horizontal capacity, γ R,Hfc : 1.56 Partial resistance factor foundation capacity, γ R,VH : 1.15 } ISO DIS V-H Bearing Capacity Envelope Fh (kips) Maximum Hull Weight Minimum Hull Weight SNAME UC=1, 2 Unfactored V-H capacity Old ISO UC=1, New ISO UC=1, Factored V-H capacity 5 4 Fv (tonnes) Stillwater spudcan reaction (triangle) Origin used for utilisation checks (diamond),5q V /γ R,VH Fh (tonnes) spud_pen ISOv W.S Calc: DHE Appvd: MJRH Date: 27-Nov-1 Factored sliding capacity Unfactored sliding capacity Fv (kips) Figure 2: Original Dec 29 DIS ISO V-H Envelope and Footing Reactions for Super Gorilla unit Page 13 - of 36

14 Location Details Spudcan Geometry Generic clay location for ISO Phase 2 Benchmarking (SNAME) Coordinates : N/A N, N/A E Depth of water : 85. m (279 ft) Jack-up Unit Details Generic Super Gorilla Design : Super Gorilla Calculated Spudcan Reactions at Predicted Penetration Preload reaction : 15,876 tonnes (35, kips) 15,87635, Stillwater reaction : 8,446 tonnes (18,621 kips) 8,446 18,621 Parameters Used in V-H Calculations Expected spudcan tip penetration : 46.4 m (152 ft) 152 Maximum spudcan contact area : m 2 (2,618 sq.ft) 2,618 Laterally projected spudcan area : 52.8 m 2 (568 sq.ft) 568 Steel/sand interaction factor, δ : N.A.. c u at maximum bearing area, c uo : 67 kpa (1,399 lb/sq.ft) 1,399 c u at spudcan tip, c ut : 7 kpa (1,462 lb/sq.ft) 1,462 Preload resistance factor, Φ P :.9 Sliding resistance factor, Φ Hfc or Φ Hfs :.64 Resistance factor for combined V-H loads, Φ VH :.85 V-H Bearing Capacity Envelope Vertical load capacity (tonnes) Generic Super Gorilla at Generic clay location for ISO Phase 2 Benchmarking (SNAME) V-H BEARING CAPACITY ENVELOPE SNAME (Rev. 3 January 28) Stillwater spudcan reaction Horizontal load capacity (kips) Unfactored V-H capacity Factored V-H capacity Factored sliding capacity Unfactored sliding capacity Horizontal load capacity (tonnes) spud_pen v2.1 Soils Database Ref. W.S. 5/13553 Calc: DHE Appvd: RWPS Date: 27-Nov-1 } Maximum Hull Weight Minimum Hull Weight SNAME UC=1, Old ISO UC=1, New ISO UC=1, Vertical load capacity (kips) Figure 3: SNAME V-H Envelope for Super Gorilla with footing reactions from ISO analyses Page 14 - of 36

15 Generic KFELS B Class at Generic clay location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE Location Details Generic clay location for ISO Phase 2 Benchmarking Coordinates : N/A N, N/A E Depth of water : 7. m (23 ft) Spudcan Geometry Jack-up Unit Details Generic KFELS B Class Design : KFELS Mod V B Class Calculated Spudcan Reactions at Seabed Level Preload reaction V Lo : 7,143 tonnes (15,748 kips) 7,143 15,748 Stillwater reaction : 4,357 tonnes (9,66 kips) 4,357 9,66 Including spudcan and leg buoyancy. Parameters Used in V-H Calculations Expected spudcan tip penetration : 34.7 m (112 ft) 112 Maximum spudcan contact area, A : m 2 (1,643 sq.ft) 1,643 Laterally projected spudcan area, As : 43.7 m 2 (47 sq.ft) 47 Steel/sand interaction factor, δ : N.A. o. c u at maximum bearing area, c uo : 44 kpa (919 lb/sq.ft) 919 c u at spudcan tip, c ut : 47 kpa (982 lb/sq.ft) 982 Preload resistance factor, γ R,PRE : 1.1 Partial resistance factor horizontal capacity, γ R,Hfc : 1.56 Partial resistance factor foundation capacity, γ R,VH : 1.1 V-H Bearing Capacity Envelope Fh (kips) ISO DIS } 9 Unfactored V-H capacity Maximum Hull Weight Minimum Hull Weight 2 8 SNAME UC=1, Fv (tonnes) Stillwater spudcan reaction (triangle) Origin used for utilisation checks (diamond),5q V /γ R,VH Factored V-H capacity Factored sliding capacity Fh (tonnes) spud_pen ISOv W.S Calc: DHE Appvd: MJRH Date: 27-Nov-1 Unfactored sliding capacity Old ISO UC=1, New ISO UC=1, Fv (kips) Figure 4: Nov 21 Revised ISO V-H Envelope and Footing Reactions for KFELS B Class Page 15 - of 36

16 Generic KFELS B Class at Generic clay location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE Location Details Generic clay location for ISO Phase 2 Benchmarking Coordinates : N/A N, N/A E Depth of water : 7. m (23 ft) Spudcan Geometry Jack-up Unit Details Generic KFELS B Class Design : KFELS Mod V B Class Calculated Spudcan Reactions at Seabed Level Preload reaction V Lo : 7,143 tonnes (15,748 kips) 7,143 15,748 Stillwater reaction : 4,357 tonnes (9,66 kips) 4,357 9,66 Including spudcan and leg buoyancy. Parameters Used in V-H Calculations Expected spudcan tip penetration : 34.7 m (112 ft) 112 Maximum spudcan contact area, A : m 2 (1,643 sq.ft) 1,643 Laterally projected spudcan area, As : 43.7 m 2 (47 sq.ft) 47 Steel/sand interaction factor, δ : N.A. o. c u at maximum bearing area, c uo : 44 kpa (919 lb/sq.ft) 919 c u at spudcan tip, c ut : 47 kpa (982 lb/sq.ft) 982 Preload resistance factor, γ R,PRE : 1.1 Partial resistance factor horizontal capacity, γ R,Hfc : 1.56 Partial resistance factor foundation capacity, γ R,VH : 1.15 V-H Bearing Capacity Envelope Fv (tonnes) ISO DIS Stillwater spudcan reaction (triangle) Origin used for utilisation checks (diamond),5q V /γ R,VH Unfactored V-H capacity Factored sliding capacity Fh (kips) Factored V-H capacity Fh (tonnes) spud_pen ISOv W.S Calc: DHE Appvd: MJRH Date: 27-Nov-1 Unfactored sliding capacity } Maximum Hull Weight Minimum Hull Weight SNAME UC=1, Old ISO UC=1, New ISO UC=1, Fv (kips) Figure 5: Original Dec 29 DIS ISO V-H Envelope and Footing Reactions for KFELS B Class Page 16 - of 36

17 Location Details Spudcan Geometry Generic clay location for ISO Phase 2 Benchmarking Coordinates : N/A Depth of water : 7. m (23 ft) Jack-up Unit Details Generic KFELS B Class Design : KFELS Mod V B Class Calculated Spudcan Reactions at Predicted Penetration Preload reaction : 7,95 tonnes (15,641 kips) 7,95 15,641 Stillwater reaction : 4,39 tonnes (9,5 kips) 4,39 9,5 Including spudcan and leg buoyancy. Parameters Used in V-H Calculations Expected spudcan tip penetration : 37.5 m (123 ft) 123 Maximum spudcan contact area : m 2 (1,643 sq.ft) 1,643 Laterally projected spudcan area : 43.7 m 2 (47 sq.ft) 47 Steel/sand interaction factor, δ : N.A.. c u at maximum bearing area, c uo : 49 kpa (1,23 lb/sq.ft) 1,23 c u at spudcan tip, c ut : 52 kpa (1,86 lb/sq.ft) 1,86 Preload resistance factor, Φ P :.9 Sliding resistance factor, Φ Hfc or Φ Hfs :.64 Resistance factor for combined V-H loads, Φ VH :.85 V-H Bearing Capacity Envelope Vertical load capacity (tonnes) Generic KFELS B Class at Generic clay location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE SNAME (Rev. 3 January 28) Unfactored V-H capacity Stillwater spudcan reaction Factored V-H capacity Factored sliding capacity Unfactored sliding capacity Horizontal load capacity (tonnes) spud_pen v2.1 Soils Database Ref. W.S Calc: DHE Appvd: RWPS Date: 3-Nov-1 } Horizontal load capacity (kips) Maximum Hull Weight Minimum Hull Weight SNAME UC=1, Old ISO UC=1, New ISO UC=1, Vertical load capacity (kips) Figure 6: SNAME V-H Envelope for KFELS B Class with footing reactions from ISO analyses Page 17 - of 36

18 4.2 FOUNDATION UTILISATIONS POST PHASE 2 BENCHMARKING The foundation utilisations are calculated using a similar vector approach for all three methods, however the location of the origin used for the vector checks is defined differently for each method. An example vector check following the original ISO methodology is shown in Figure 7 below: 25 F V (MN) 2 Unfactored bearing capacity envelope Stillwater footing reaction Factored bearing capacity envelope F H (MN) Factored sliding capacity envelope Unfactored sliding capacity envelope Figure 7: Example Vertical-Horizontal Capacity Envelope Showing Bearing Capacity Check The V-H bearing capacity check is performed by measuring the ratio of the distance of the storm footing reaction point from the utilisation origin to the distance from the utilisation origin to the factored V-H bearing capacity envelope along the same vector direction, as shown in Figure The sliding check compares the maximum horizontal load component of the storm footing reactions with the factored sliding capacity envelope. Figure 8 shows an example of the sliding check following the original ISO (29) methodology. Page 18 - of 36

19 25 F V (MN) 2 Unfactored bearing capacity envelope Stillwater footing reaction Factored bearing capacity envelope F H (MN) Factored sliding capacity envelope Unfactored sliding capacity envelope Figure 8: Example Vertical-Horizontal Capacity Envelope showing Sliding Capacity Check Sliding check: In the case of clay γ R,HFc = 1,56 U F = Q γ H VH R, Hfc =, Table 4-1 and Table 4-2 show a comparison of the foundation utilisations obtained using the ISO footing reactions for the Super Gorilla and KFELS B Class units following the revised ISO, the original benchmarked ISO and the SNAME methodologies. Note, the values marked in red represent the maximum utilisation for which the additional settlement comparison is performed. Furthermore utilisations marked with an s are based on the sliding capacity rather than the bearing capacity. Due to the differing intersections of the factored V-H curve and factored sliding lines for the ISO and SNAME methods, in some cases the SNAME utilisation is calculated using the factored sliding line whereas the ISO uses the V-H bearing capacity envelope. Page 19 - of 36

20 Table 4-1 Bearing Capacity Utilisations for Super Gorilla Storm Heading Leg New ISO [1] Utilisations New ISO Old ISO (29) [2] SNAME / SNAME Comparisons Old ISO / SNAME New ISO / Old ISO Hull Weight = 19394t Hull Weight = 1729t SNAME U = 1. ISO DIS (29) U = 1. ISO DIS revised U = 1. Bow,4 s,4 s,91 s,44,44 1, Port,4 s,4 s,9 s,44,44 1, Starboard 1,31 1,45 1,72,76,84,9 Bow,5,59,85 s,59,69,85 Port,41 s,41 s,92 s,45,45 1, Starboard 1,18 1,31 1,48,8,89,9 Bow,81,92,97,84,95,88 Port,36 s,36 s,8 s,45,45 1, Starboard,81,94,97,84,97,86 Bow,4 s,4 s,89 s,45,45 1, Port,39 s,39 s,89 s,44,44 1, Starboard 1,2 1,36 1,52,79,89,88 Bow,43,52,82 s,52,63,83 Port,38 s,38 s,85 s,45,45 1, Starboard 1,3 1,17 1,28,8,91,88 Bow,71,81,81,88 1,,88 Port,34 s,34 s,77 s,44,44 1, Starboard,71,81,81,88 1,,88 V-H Low F H,88 1, 1,,88 1,,87 V-H High F H,8,91 1,,8,91,87 Sliding,67 s,77 s 1, s,67,77,87 V-H Low F H,88 1, 1,,88 1,,88 V-H High F H,89 1, 1,8 s,49,56,89 Sliding 1, s 1, s 2,26 s,44,44 1, V-H Low F H 1, 1,15 1,19,84,97,87 V-H High F H 1, 1,12 1,88 s,53,6,89 Sliding 1, s 1, s 2,26 s,44,44 1, [1] New ISO refers to the November 21 revised ISO foundation capacity checks [2] Old ISO refers to the December 29 version of the ISO DIS used in the benchmarking (Ref. [2]) Page 2 - of 36

21 Table 4-2 Bearing Capacity Utilisations for KFELS B Class Utilisations Comparisons Storm Heading Leg New ISO [1] New ISO Old ISO (29) [2] SNAME / SNAME Old ISO / SNAME New ISO / Old ISO Hull Weight = 169,8t Hull Weight = 877,3t SNAME U = 1. ISO DIS (29) U = 1. ISO DIS revised U = 1. Bow,32,38,45 S,71,84,84 Port,3,36,45 S,67,8,83 Starboard 1,11 1,24 1,52,73,82,9 Bow,57,66,42 S 1,36 1,57,86 Port,26 S,26 S,45 S,58,58 1, Starboard 1,4 1,16 1,34,78,87,9 Bow,82,94,83,99 1,13,87 Port,26 S,26 S,44 S,59,59 1, Starboard,84,96,8 1,5 1,2,88 Bow,25 S,3,43 S,58,7,83 Port,26 S,29,43 S,6,67,9 Starboard,99 1,1 1,19,83,92,9 Bow,47,55,42 S 1,12 1,31,85 Port,25 S,25 S,43 S,58,58 1, Starboard,89 1,4 1,,89 1,4,86 Bow,71,8,58 1,22 1,38,89 Port,25 S,25 S,43 S,58,58 1, Starboard,73,82,61 1,2 1,34,89 V-H Low F H,88 1, 1,,88 1,,8?? V-H High F H,87,99 1,,87,99,84 Sliding,68 s,59 s 1, s,68,59 1,15 V-H Low F H,88 1, 1,,88 1,,88 V-H High F H,89 1, 1,33 s,67,75,89 Sliding 1, s 1, s 1,68 s,6,6 1, V-H Low F H 1, 1,35 1,27,79 1,6,74 V-H High F H 1, 1,23 1,46,68,84,81 Sliding 1, s 1, s 1,68 s,6,6 1, [1] New ISO refers to the November 21 revised ISO foundation capacity checks [2] Old ISO refers to the December 29 version of the ISO DIS (Ref. [2]) Page 21 - of 36

22 4.3 STEP 3A ADDITIONAL SETTLEMENT CALCULATIONS The maximum level of additional settlement predicted for the Super Gorilla s starboard leg for a storm heading of 6 for the Step 3a displacement check using each of the three methodologies is shown in Table 4-3 below along with the relevant comparisons. Note that in order to make a valid comparison the additional settlements using SNAME were calculated using the storm footing reactions obtained from the ISO analysis. Table 4-3 Additional Settlement for Super Gorilla unit Storm Heading Leg Additional Settlement New ISO Old ISO SNAME New ISO / SNAME Comparisons Old ISO / SNAME New ISO / Old ISO 6 Starboard 4, 7,2 9,2,43,78, The maximum level of additional settlement predicted for the KFELS B Class unit s starboard leg for a storm heading of 6 for the Step 3a displacement check using each of the three methodologies is shown in Table 4-4 below along with the relevant comparisons. Table 4-4 Additional Settlement for KFELS B Class unit Storm Heading Leg Additional Settlement New ISO Old ISO SNAME New ISO / SNAME Comparisons Old ISO / SNAME New ISO / Old ISO 6 Starboard 2, 3,2 4,1,49,78,63 Page 22 - of 36

23 5 ANALYSIS OF THE RESULTS 5.1 NEW ISO VS OLD ISO Figure 9 and Figure 1 show the differences between the factored V-H bearing capacity checks using the new and old ISO methods for the Super Gorilla and KFELS B Class for the clay soil profile. 25 F V (MN) 2 Unfactored bearing capacity envelope New ISO factored bearing capacity envelope Old ISO factored bearing capacity envelope 15 Stillwater footing reaction 1 5 New ISO origin for utilisations Old ISO origin for utilisations F H (MN) Factored sliding capacity envelope Unfactored sliding capacity envelope Figure 9: Comparison of New ISO with Old ISO Bearing Capacity and Sliding Envelopes - Super Gorilla 1 F V (MN) 9 8 Unfactored bearing capacity envelope New ISO factored bearing capacity envelope Old ISO factored bearing capacity envelope 7 6 Stillwater footing reaction New ISO origin for utilisations Old ISO origin for utilisations Factored sliding capacity envelope Unfactored sliding capacity envelope F H (MN) Figure 1: Comparison of New ISO with Old ISO Bearing Capacity and Sliding Envelopes - KFELS B Class Page 23 - of 36

24 5.1.2 The factored V-H bearing capacity envelope using the revised ISO is consistently larger due to the use of a material factor of 1,1 for full penetration, hence the utilisations will be lower than with the old ISO. The unfactored envelope and both unfactored and factored sliding lines remain unchanged The utilisation origin has increased slightly compared to the old ISO also due to the revision of the resistance factor. The effect of this change on its own would be to increase the utilisations slightly The results presented in Table 4-1 and Table 4-2 mirror the effects of the new larger factored V-H bearing capacity envelope; all the bearing capacity utilisations for both units have reduced by 1% - 17% when compared with the old ISO results. Utilisations based on sliding capacity remain unchanged between the two methods as demonstrated by Figure 9 above, as the same method of calculation is used in both versions The level of additional settlements predicted by the revised ISO method for the Super Gorilla and KFELS B Class units are 3,2m and 1,2m less than that predicted by the old ISO method which is due to the difference in the size of the factored yield envelope Both the utilisations shown in Table 4-1 and Table 4-2 and the chart shown in Figure 9 demonstrate that, for the case of the Super Gorilla, lower bearing capacity utilisations are achieved using the new ISO method when compared with the old ISO method with about a 1% - 17% difference for the Super Gorilla and KFELS B Class storm cases. Additional settlements are also reduced by around 44% and 37% for the Super Gorilla and KFELS B Class units respectively. 5.2 NEW ISO VS SNAME Figure 11 and Figure 12 show the differences between the new ISO and SNAME methods with regards to the shape of the yield envelopes for the Super Gorilla and KFELS units. Note, the SNAME envelope does not usually include consideration of the weight of backfill or spudcan soil buoyancy, however for the purposes of the comparison the SNAME envelopes and origin for utilisation checks have been shifted up the F v axis to account for the weight of backfill and spudcan soil buoyancy and to enable a direct comparison with the ISO envelopes. Page 24 - of 36

25 F V (MN) 25 2 SNAME unfactored bearing capacity envelope SNAME factored bearing capacity envelope New ISO unfactored bearing capacity envelope New ISO factored bearing capacity envelope Stillwater footing reaction New ISO origin for utilisations SNAME factored sliding capacity envelope SNAME unfactored sliding capacity envelope New ISO factored sliding capacity envelope New ISO unfactored sliding capacity envelope F H (MN) Figure 11: Comparison of New ISO with SNAME Bearing Capacity and Sliding Envelopes for Super Gorilla unit (SNAME shifted for backfill and spudcan soil buoyancy) 1 F V (MN) 9 8 SNAME unfactored bearing capacity envelope SNAME factored bearing capacity envelope New ISO unfactored bearing capacity envelope New ISO factored bearing capacity envelope Stillwater footing reaction New ISO origin for utilisations SNAME factored sliding capacity envelope SNAME unfactored sliding capacity envelope New ISO factored sliding capacity envelope New ISO unfactored sliding capacity envelope F H (MN) Figure 12: Comparison of New ISO with SNAME Bearing Capacity and Sliding Envelopes for KFELS B Class unit (SNAME shifted for backfill and spudcan soil buoyancy). Arrows indicate utilisation check for case where SNAME utilisation is less than ISO utilisation: Min. hull weight, storm heading = 12, Bow Leg: U ISO =,71, U ISO=,58 U ISO/U SNAME = 1,22 Page 25 - of 36

26 5.2.2 Comparison of the utilisations obtained with the new ISO methodology and SNAME is more complicated than for the comparison of the ISO DIS due to the number of differences that result in different: Unfactored V-H envelopes; Unfactored sliding envelopes; Intersections between the factored V-H bearing capacity envelope and factored sliding envelopes; V-H bearing capacity resistance factors; Origins used to construct factored envelopes; Origins used to determine foundation utilisations; Not all of these result in lower utilisations for the ISO methodology, precluding a straightforward comparison of utilisations Bearing Capacity The bearing capacity envelopes shown in Figure 11 and Figure 12 clearly show that the SNAME factored V-H bearing capacity envelope is entirely inside the ISO factored V-H bearing capacity envelope. For the case of the Super Gorilla unit this has resulted in consistently lower utilisations for the ISO method compared to SNAME as demonstrated in Table 4-1 for the Super Gorilla. A comparison of the cases where neither methodology results in a sliding check shows the new revised ISO utilisations to be between 76% - 88% of the SNAME utilisations. The margin, however, reduces for footing reactions that are close to the factored V-H envelopes for a horizontal force component of less than around 7,MN where the two envelopes are relatively close. In the case of the KFELS B Class unit analysis, however, the ISO does not necessarily result in lower utilisations with ISO utilisations ranging between 78% and 122% of those from SNAME for the case where both methodologies result in a V-H bearing capacity envelope check. This is a consequence of the different origins used to define utilisation in the new revised ISO and SNAME methods as illustrated in Figure 12 for the case of the minimum hull weight bow leg footing reaction for a storm heading of 12 where U ISO /U SNAME =1,22. The preload ballast capacity of the KFELS B Class as a proportion of the stillwater footing reaction is less than for the Super Gorilla. The stillwater footing reaction is therefore closer to the factored V-H envelope and, for some cases, the SNAME utilisation will be lower than for the revised ISO which uses the new utilisation origin that is significantly further from the factored envelope than the stillwater footing reaction. To understand this more easily, for a given storm footing reaction point and with reference to a single factored envelope, the closer the stillwater footing reaction is to the ISO utilisation origin, the more similar the utilisations will be for the ISO and SNAME methodologies. Conversely the closer the stillwater footing reaction is to Page 26 - of 36

27 the factored V-H envelope, the larger the ISO utilisation will be compared to the SNAME utilisation. The interplay of the differing utilisation origins, V-H bearing capacity envelopes (further complicated by the change in the incorporation of the laterally projected area component), resistance factors, origins for constructing the factored envelope and intersection of the V-H and sliding lines means that no one method will consistently provide lower utilisations than another - each can give utilisations that are greater or lower than the other depending on the rig s preload capabilities and position of the particular storm footing reaction in relation to the corresponding factored envelopes. It is therefore not possible to state that the new ISO will produce utilisations that are 5% less than SNAME, all one can conclude is that they will be different to those given by SNAME. The origin of the utilisations specified in the ISO documents does, however, have a more rigorous basis compared to SNAME, which uses the stillwater footing reaction, as the origin can, in the case of rigs with very limited preload capabilities, result in apparently low foundation utilisations for storm footing reactions that are, in absolute terms, very close to the factored V-H envelope Sliding Capacity The sliding capacity utilisations calculated according to the SNAME methodology are only 44% of those calculated using the new ISO methodology. This is demonstrated by both the sliding utilisations shown in Table 4-1 and by the chart shown in Figure 11. For the KFELS B Class the SNAME sliding capacity utilisations are around 59% of the SNAME sliding capacity utilisations Additional Settlement The additional settlements for the Super Gorilla s starboard leg for a storm heading of 6 calculated using the revised ISO method are 4,2m compared to 9,2m using SNAME. Similarly for the KFELS B Class, the additional settlements for the starboard leg for a storm heading of 6 calculated using the revised ISO method are 2,m compared to 4,1m using SNAME. There is clearly a significant reduction in the additional settlements caused by expanding the V-H envelope in the Step 3a check due to the larger factored V-H bearing capacity envelope which requires the V-H envelope to be expanded by a lesser amount in order to encompass all the storm footing reactions. 5.3 SAND FOUNDATIONS Sand foundations have not been considered in this addendum due to the fact that the November 21 ISO approach is identical to the December 29 ISO approach used in the Benchmarking study. A comparison of the ISO approach to the SNAME approach is described in GLND Report L25217 (Ref. [3]) for the Super Gorilla and L25216 (Ref. [4]) for the KFELS B-Class. A summary of utilisations from these reports is repeated below. Page 27 - of 36

28 Table 5-1 Final assessment results for the Super Gorilla Criteria ISO SNAME ISO/SNAME Spudcan penetration (m),91,95,96 Utilisations Heading UC Heading UC - Preload Capacity 6 1,16 6 1,17,99 Foundation bearing capacity Additional settlements (m) Windward leg sliding 6 1,63 6 1,82,9 -,1 -,13, ,3 12 1,22 1,6 Table 5-2 Final assessment results for the KFELS B-Class Criteria ISO SNAME ISO/SNAME Spudcan penetration (m) 1,95 2,,98 Utilisations Heading UC Heading UC - Preload Capacity 6 1,11 6 1,15,97 Foundation bearing capacity Additional settlements (m) Windward leg sliding 6 1,34 6 1,54,87 6,1 6,17,59 12,84 12,85,99 Please note that the footing reactions used to calculate the SNAME UC s in Table 5-1 and Table 5-2 are different to those used to calculate the ISO UC s as the SNAME footing reactions were calculated using the SNAME site assessment methodology rather than the ISO methodology. The corresponding SNAME and ISO V-H bearing capacity envelopes and sliding envelopes are shown in Figure 13 to Figure 16 for the Super Gorilla and KFELS B Class units. Page 28 - of 36

29 Generic Super Gorilla at Generic medium dense sand location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE Location Details Spudcan Geometry Generic medium dense sand location for ISO Phase 2 Benchmarking Coordinates : N/A N, N/A E Depth of water : m (4 ft) Jack-up Unit Details Generic Super Gorilla Design : Super Gorilla Calculated Spudcan Reactions at Seabed Level Preload reaction : 15,876 tonnes (35,1 kips) 15,87635,1 Stillwater reaction : 8,473 tonnes (18,68 kips) 8,473 18,68 Parameters Used in V-H Calculations Expected spudcan tip penetration :.91 m (3 ft) 3 Maximum spudcan contact area : m 2 (1,682 sq.ft) 1,682 Laterally projected spudcan area : 7.7 m 2 (83 sq.ft) 83 Steel/sand interaction factor, δ : 29. o 29. c u at maximum bearing area, c uo : kpa c u at spudcan tip, c ut : kpa Preload resistance factor, γ R,PRE : 1.1 Partial resistance factor horizontal capacity, γ R,Hfc : 1.25 Partial resistance factor foundation capacity, γ R,VH : 1.1 } ISO DIS V-H Bearing Capacity Envelope F H (kips) Maximum Hull Weight Minimum Hull Weight 16 Unfactored V-H capacity 14 Factored V-H capacity Fv (tonnes) Stillwater spudcan reaction (triangle) Origin used for utilisation checks (diamond) 2 15 Fv (kips) 4 Factored sliding capacity 1 2 Unfactored sliding capacity F H (tonnes) spud_pen ISOv W.S Calc: DHE Appvd: MJRH Date: 3-Oct-1 Figure 13: ISO DIS V-H Envelope for Super Gorilla with footing reactions from ISO analyses Page 29 - of 36

30 Generic Super Gorilla at Generic medium dense sand location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE Location Details Spudcan Geometry Generic medium dense sand location for ISO Phase 2 Benchmarking Coordinates : N/A N, N/A E Depth of water : m (4 ft) Jack-up Unit Details Generic Super Gorilla Design : Super Gorilla Calculated Spudcan Reactions at Predicted Penetration Preload reaction : 15,876 tonnes (35, kips) 15,87635, Stillwater reaction : 8,473 tonnes (18,68 kips) 8,473 18,68 Parameters Used in V-H Calculations Expected spudcan tip penetration : 1. m (3 ft) 3 Maximum spudcan contact area : m 2 (1,793 sq.ft) 1,793 Laterally projected spudcan area : 8.2 m 2 (88 sq.ft) 88 Steel/sand interaction factor, δ : 29. o 29. c u at maximum bearing area, c uo : N.A. ####### c u at spudcan tip, c ut : N.A. ####### Preload resistance factor, Φ P :.9 Sliding resistance factor, Φ Hfc or Φ Hfs :.8 Resistance factor for combined V-H loads, Φ VH :.9 } SNAME (Rev. 3 January 28) V-H Bearing Capacity Envelope Horizontal load capacity (kips) Maximum Hull Weight 16 Minimum Hull Weight Unfactored V-H capacity 5 Vertical load capacity (tonnes) Factored V-H capacity Stillwater spudcan reaction Vertical load capacity (kips) 2 Factored sliding capacity Unfactored sliding capacity Horizontal load capacity (tonnes) spud_pen v2.1 Soils Database Ref. W.S. 5/13553 Calc: DHE Appvd: RWPS Date: 3-Oct-1 Figure 14: SNAME V-H Envelope for Super Gorilla with footing reactions from SNAME analyses Page 3 - of 36

31 Generic KFELS B Class at Generic medium dense sand location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE Location Details Spudcan Geometry Generic medium dense sand location for ISO Phase 2 Benchmarking Coordinates : N/A N, N/A E Depth of water : 16.7 m (35 ft) Jack-up Unit Details Generic KFELS B Class Design : KFELS Mod V B Class Calculated Spudcan Reactions at Seabed Level Preload reaction : 7,1 tonnes (15,653 kips) 7,1 15,653 Stillwater reaction : 4,314 tonnes (9,511 kips) 4,314 9,511 Parameters Used in V-H Calculations Expected spudcan tip penetration : 1.95 m (6 ft) 6 Maximum spudcan contact area : 91.1 m 2 (981 sq.ft) 981 Laterally projected spudcan area : 6.3 m 2 (68 sq.ft) 68 Steel/sand interaction factor, δ : 29. o 29. c u at maximum bearing area, c uo : kpa c u at spudcan tip, c ut : kpa Preload resistance factor, γ R,PRE : 1.1 Partial resistance factor horizontal capacity, γ R,Hfc : 1.25 Partial resistance factor foundation capacity, γ R,VH : 1.1 } ISO DIS V-H Bearing Capacity Envelope Fv (tonnes) Stillwater spudcan reaction (triangle) Origin used for utilisation checks Unfactored V-H capacity Fh (kips) Factored V-H capacity Maximum Hull Weight Minimum Hull Weight Factored sliding capacity Fv (kips) 1 Unfactored sliding capacity Fh (tonnes) spud_pen ISOv W.S Calc: DHE Appvd: MJRH Date: 19-Nov-1 Figure 15: ISO DIS V-H Envelope for KFELS B Class with footing reactions from ISO analyses Page 31 - of 36

32 Generic KFELS B Class at Generic medium dense sand location for ISO Phase 2 Benchmarking V-H BEARING CAPACITY ENVELOPE Location Details Spudcan Geometry Generic medium dense sand location for ISO Phase 2 Benchmarking Coordinates : N/A Depth of water : 16.7 m (35 ft) Jack-up Unit Details Generic KFELS B Class Design : KFELS Mod V B Class Calculated Spudcan Reactions at Predicted Penetration Preload reaction : 7,97 tonnes (15,646 kips) 7,97 15,646 Stillwater reaction : 4,312 tonnes (9,56 kips) 4,312 9,56 Parameters Used in V-H Calculations Expected spudcan tip penetration : 2. m (7 ft) 7 Maximum spudcan contact area : 97.5 m 2 (1,49 sq.ft) 1,49 Laterally projected spudcan area : 6.7 m 2 (72 sq.ft) 72 Steel/sand interaction factor, δ : 29. o 29. c u at maximum bearing area, c uo : N.A. ####### c u at spudcan tip, c ut : N.A. ####### Preload resistance factor, Φ P :.9 Sliding resistance factor, Φ Hfc or Φ Hfs :.8 Resistance factor for combined V-H loads, Φ VH :.9 } SNAME (Rev. 3 January 28) V-H Bearing Capacity Envelope Vertical load capacity (tonnes) Stillwater spudcan reaction Horizontal load capacity (kips) Unfactored V-H capacity Factored V-H capacity Maximum Hull Weight Minimum Hull Weight Factored sliding capacity Vertical load capacity (kips) 1 Unfactored sliding capacity Horizontal load capacity (tonnes) spud_pen v2.1 Soils Database Ref. W.S Calc: DHE Appvd: RWPS Date: 2-Nov-1 Figure 16: SNAME V-H Envelope for KFELS B Class with footing reactions from SNAME analyses Page 32 - of 36

33 6 CONCLUSIONS 6.1 A comparison has been made of the V-H bearing capacity checks and utilisations using the methodology described in SNAME, the December 29 ISO DIS used for benchmarking and the November 21 revision to the ISO V-H bearing capacity foundation checks section. 6.2 The comparison has been limited to the clay foundation case as the sand soil profile resulted in partial spudcan penetrations being predicted for which the revision to the ISO has a negligible effect. 6.3 A comparison of the ISO approach to the SNAME approach is described in GLND Report L25217 (Ref. [3]) for the Super Gorilla and L25216 (Ref. [4]) for the KFELS B-Class which shows the foundation bearing capacity utilisations and additional settlements to be lower using the ISO DIS methodology compared to SNAME. 6.4 The reduced V-H resistance factor implemented in the November 21 revision to the ISO results in a factored V-H bearing capacity envelope that will always be larger than that calculated using the December 29 ISO DIS methodology. 6.5 The November 21 revision gives a factored capacity envelope that exceeds that of SNAME. The increase in size is greatest for sliding failure for spudcans with deep penetrations in clay. 6.6 Furthermore the revised origin used to construct the factored V-H bearing capacity envelope has also resulted in a larger factored V-H bearing capacity envelope. 6.7 The results of the comparison for the Super Gorilla unit indicate that the utilisations determined for the set of storm footing reactions examined are consistently lower using the November 21 revised ISO compared to both the December 29 ISO DIS and the SNAME Recommended Practice. 6.8 The results of the comparison for the KFELS Mod V B unit indicate that the utilisations determined for the set of storm footing reactions examined are consistently lower using the November 21 revised ISO compared to the December 29 ISO DIS. This is due to the reduced V-H bearing capacity resistance factor introduced in the November 21 revision. 6.9 The utilisations determined for the KFELS Mod V B unit may, however, be higher or lower than those calculated using the methodology described in the SNAME Recommended Practice. This is due to the unit having a proportionately lower preload ballast capacity compared to the Super Gorilla and consequently the stillwater footing reaction is relatively closer to the factored V-H bearing capacity envelope, result in lower SNAME foundation utilisations compared to those given by either the ISO DIS or the November 21 revision of the ISO. 6.1 This is a result of the new origin for defining foundation utilisations that was introduced in the ISO specifically to address the issue of relatively low foundation utilisations that can be calculated using the SNAME Recommended Practice for storm footing reactions close to the factored V-H bearing capacity envelope for units with low preload ballast capacities Importantly, SNAME utilisations of unity will always correspond to utilisations that are less than unity using the November 21 revision of the ISO For both units the additional settlements required to expand the V-H envelope for a Step 3a check for the November 21 revised ISO are significantly lower than those using both the December 29 ISO DIS and SNAME Recommended Practice as the Page 33 - of 36

34 November 21 revised ISO factored V-H bearing capacity envelope is always larger than those calculated using the December 29 ISO DIS and SNAME Recommended Practice The ISO DIS (29) and revised ISO utilisations are always significantly lower than SNAME when limited by lateral/sliding capacity due the greatly increased horizontal foundation capacity from the ISO mythologies. Page 34 - of 36

35 This report is intended for the sole use of the person or company to whom it is addressed and no liability of any nature whatsoever shall be assumed to any other party in respect of its contents. GL NOBLE DENTON Signed: David Edwards, MEng., M.Sc., Ph.D., DIC Senior Geotechnical Engineer, Jack-up and Geotechnical Engineering Countersigned: Richard Stonor, B.Sc., Ph.D., C.Eng., MRINA Manager, Jack-up and Geotechnical Engineering Dated : London, 3 th November 21 Page 35 - of 36

36 REFERENCES [1] SNAME Technical and Research Bulletin 5-5A. Recommended Practice for Site Specific Assessment of Mobile Jack-Up Units, 1st Ed., Rev 2., Jan 22. [2] ISO , Petroleum and natural gas industries - Site-specific assessment of mobile offshore units - Part 1: Jack-Ups, Draft DIS, 12, 29. [3] GL Noble Denton Report No. L25217, ISO PHASE 2 BENCHMARKING ISO (DIS) VALIDITY CHECK, LETOURNEAU SUPER GORILLA CLASS, Rev 2, 19 TH November 21. [4] GL Noble Denton Report No. L25316, ISO PHASE 2 BENCHMARKING ISO (DIS) VALIDITY CHECK, KFELS B CLASS, Rev, 2 th November 21. Page 36 - of 36