Interpretative Report for Phase-3 Lax

Table topStudies

ProjectHazira LNG

Originating CompanyBPDO

PCAP Control ID Number

Document Number(Later)

Document TitleTable Top Studies (Concept Select Note)

Document Revision01R

Document StatusIssued for Review

Originator / AuthorAnant Kumar Lal

Security ClassificationUnclassified/Restricted/Confidential/Most Confidential

ECCNEAR 99

Issue Date7th Jan-2014

Revision History is shown next page

Revision History:REVISION STATUSAPPROVAL

Rev #Date of IssueDescriptionOriginatorCheckerApprover

01R7th-Jan-2014IFR First Issue for ReviewRam K.Amit HiraniPartha Sarathi

Signatures for this revision:

Rev#DateRolePCAP Authority RoleNameSignature or electronic reference (email)

Summary

Keywords

Table of Contents1.Introduction42.Background:42.1.Rotterdam Tabletop:53.Tabletop studies:63.1.Concrete Structure for Hard top:63.2.Optimisation Study for Hard Tabletop:83.2.1.Columns83.2.2.Piles93.2.3.STAAD Analyses:123.2.4.Column Pile connection:143.3.Steel Plate thickness for Soft Table top option:153.4.Stiffener:183.5.Structure:184.Calculations:185.Comparison of concepts:195.1.Sturctural description:195.2.Constructability:205.3.Foundation concept:205.4.Quantities215.5.Opportunities for Improvement:215.5.1.Converting hard impact to soft impact215.5.2.Finalising rig foot print216.Conclusions:226.1.Hard Table Top:226.2.Soft Table Top22

IntroductionIn Discussion project introduction/objectives/commentary on adequacy of SI and Fugro (Report No: FGTL/HLPL/ Vol-II (Part 1)/Interpretative/ED/592/13/Rev-3). A brief description of Rotterdam table top too was presented in 2.1.

Soil Stratigraphy:

Table top arrangement shall protect the Christmas tree and piping against dropped objects. List of dropped objects is summarised in table 2.1. If drill rig moves atop the table top, the structure should withstand the rig loads as well. Summary of rig loads and drop objects are furnished in Fig 2.1:

Introduction:Include in introduction a discussion on variability of stratigraphy across siteInclude in this section a layout and location plan of CPTs per structure Include CPT profile sections in annex Methodology:

Based on EN 1997-1:2003(E), the design bearing resistance has been calculated using equation mentioned in section D3 and D4, considering undrained sub-surface conditions for cohesive soil such as Silt & Clay and drained sub-surface conditions for cohesionless soils such as Sand & Gravel. The bearing capacity calculated based on the equation mentioned below;

2.2.1 Estimation of Bearing Capacity:2.2.1.1 Undrained Subsurface Condition:The design bearing resistance may be calculated from:R/A' = (+2) cu bc sc ic + qWith the dimensionless factors for: The inclination of the foundation base: bc = 1 2 / ( + 2); The shape of the foundation:sc = 1+ 0.2 (B'/L'), for a rectangular shape;sc = 1.2, for a square or circular shape. The inclination of the load, caused by a horizontal load H:

with H A' cu.

2.2.1.2 Drained Subsurface Condition:The design bearing resistance may be calculated from:R/A' = c' Nc bc sc ic + q' Nq bq sq iq + 0.5 ' B 'N b s iWith the design values of dimensionless factors for:

The bearing resistance:Nq = e tan' tan2 (45+ '/2)Nc = (Nq - 1) cot 'N = 2 (Nq- 1) tan ', where '/2 (rough base)

The inclination of the foundation base:bc = bq - (1 - bq) / (Nc tan )bq = b = (1 - tan )2

The shape of foundation:sq = 1 + (B' / L' ) sin ', for a rectangular shape;sq = 1 + sin ', for a square or circular shape; s = 1 0,3 (B'/L ), for a rectangular shape;s = 0.7, for a square or circular shape sc = (sq.Nq -1)/(Nq - 1) for rectangular, square or circular shape; The inclination of the load, caused by a horizontal load H:ic = iq - (1 - iq) / (Nc. tan ');iq = [1 - H/(V + A'c'cot ')]m;i = [1 - H/(V + A'c'cot ')]m+1.Where:m = mB = [2 + (B '/ L')] / [1 + (B' / L')] when H acts in the direction of B';m = mL = [2 + (L' / B')] / [1 + (L' / B')] when H acts in the direction of L'.In cases where the horizontal load component acts in a direction forming an angle with the direction of L', m may be calculated by:m = m = mL cos2 + mB sin2.

2.2.2 Estimation of Settlement:

The following is a semi-empirical method for calculating settlements of spread foundations in coarse soil. The value for Young's modulus of elasticity (E') derived from the cone penetration resistance (qc), to be used in this method is:

E' = 2.5qc for axisymmetric (circular and square) foundations; andE'= 3,5qc, for plane strain (strip) foundations.The sett1elllent (s) of a foundation under load pressure (q) is expressed as:

WhereC1 is 1 0.5 x [ vo / (q - 'vo)];C2 is 1.2 + 0.2Xlg tC3 is the correction factor for the shape of the spread foundation:- 1.25 for square foundations; and- 1.75 for strip foundations with L > 10B;'vo is the initial effective vertical stress at the level of the foundation;zi is the depth influenced by the foundation pressure and width, respectively, in mlz is a strain influence factor (see below).

Design Parameters for Proposed Structure:1. Generalized Sub-surface Soil Model based on PCPTs Piperack-I

Document Title: Geotechnical Interpretative report for Hazira LNG Phase-3Revision: 01R

Page 15 of 24All rights reserved. Copyright is vested in Shell Global Solutions International B.V. and/or its affiliates. Neither the whole nor any part of this Document may be reproduced or distributed in any form or by any means(electronic, mechanical, reprographic, recording or otherwise) without the prior written consent of the copyright owner.

Page 7 of 23Doc. no.: ????The information contained on this page is subject to the disclosure on the front page of this document.S.NoSoil DescriptionFromTo QcThicknessUnit weightNormal stress (at mid level of each layer)u (at mid level of each layer)Effective stress ' (at mid level of each layer)Cu 'E K0KaKpDr(Baldi)U (preconsolidation pressure)preconsolidation pressure (assume MSL CD+2m)

mmMpamkN/m3kPakPaKpaKpaMPaKpaKpa

1Soft Clay0.001.500.251.5017.5013.1375.814260.560.392.56-21%013

2Layer-1Medium Dense Sand1.502.105.500.6018.5031.80181433220.460.293.3987%0

3Layer-2Soft Clay2.102.400.300.3017.5039.98221815260.560.392.56040


5Layer-4Loose Sand2.853.102.600.2518.0053.182924146260.560.392.56053


7Layer-6Loose Sand9.1011.752.002.6518.00190.2810288103260.560.392.5624166


1. Generalized Sub-surface Soil Model based on PCPTs Piperack-II1. Generalized Sub-surface Soil Model based on PCPTs Pipe sleeper1. Generalized Sub-surface Soil Model based on PCPTs Air Heater1. Generalized Sub-surface Soil Model based on PCPTs BOG Compressor1. Generalized Sub-surface Soil Model based on PCPTs Shell Tube Vaporiser1. Generalized Sub-surface Soil Model based on PCPTs Electrical Sub-station1. Generalized Sub-surface Soil Model based on PCPTs Ware house

Ground Water Table:water table etc.- measured values and assumptions.

Fig 2.1.a Plan of Rotterdam tabletop.

Fig 2.1.b section of Rotterdam tabletopDesign Basis:Bearing Capacity and Settlement philosophy followedTypical Calc for each of the following: Bearing capacity and settlement calculations for Piperack-I Bearing capacity and settlement calculations for Piperack-II Bearing capacity and settlement calculations for Pipe sleeper Bearing capacity and settlement calculations for Air Heater Bearing capacity and settlement calculations for BOG Compressor Bearing capacity and settlement calculations for Shell Tube Vaporiser Bearing capacity and settlement calculations for Electrical Sub-station Bearing capacity and settlement calculations for Ware houseSummary :Ultimate B.C and Settlement Calc (Immediate+Consolidation) for all the structures above with the different size and depth of footing Appendix 1 CPT Profiles per structure locationAppendix 2 Old Fugro Report attached (with superceded sections watermarked)

Hard Tabletop

DescriptionUOMQty for 2m X 2m spacingQty for 5m X 5m spacing

Ramp - Concrete Qtycum200

Floors - Concrete Qtycum31502750

Columnscum315126

RebarMT398311

3078

Table 3.2.2 a

DescriptionRemarks

Pile height in m1517.52022.52527.5

Pile capacity in kNs247403542589643703

Rig load in Tons920

Number of piles for rig load402247184169155142Rig foot print is assumed 10m x 2m; and requirement of piles is computed for 10m length, and scaled for 110 m length

Self weight of the table top550055005500550055005500

Number of piles for self weight of table top218134100928477

Total no of piles621381284261239219

Columns quantity in m3298.08182.9136125115105Column size is assumed as 400 mm x 400 mm

Piling quantitiy in m3965692589608620625

Concrete quantity (piles + columns)1263875725734735730

Fig 3.2.2.b; Concrete quantity in m3 vs depth

As can be seen from Fig 3.2.2.b, optimum depth for pile penetration is 20 m.STAAD Analyses:STAAD analyses were performed for different rig locations, for a rig foot print of 10 m X 12 m, with distance between rig footprints varied between 5m to 10 m. Optimised solutions for pile quantities were arrived at and the same are reported in table 3.2.3.

Table 3.2.3.a

LSl.No.CasePiles quantity m3columns quantity m3Remarks

1

1000110Spacing between rig foot print 5 m

2

1000110Spacing between rig foot print 10 m

3

1425150Spacing between rig foot print 5 m & 10 m

Quantities reported in table 3.2.3 are substantially higher compared to table 3.2.2.a as STAAD analyses accounts for stress concentrations. Central columns receive higher load compared to the other columns. Typical reactions for an assumed pile layout is shown in Fig 3.2.3.a. Tentative pile arrangement is shown in Fig 3.2.3.b

Fig. 3.2.3.a. Unequal pile reactions from STAAD analyses

Fig 3.2.3 b: Tentative pile arrangement

Column Pile connection:Two load transfer arrangements from slab to piles are shown in Fig 3.2.4. Table 3.2.4 compares costs of option 1 & option2. From Table 3.2.4, option 1 is costlier, compared to option 2.

Fig 3.2.4Load Transfer arrangements from flat slab to Soil

Table 3.2.4; comparison of pile and column arrangement

No of piles below column45

DescriptionOption 1Option 2Option 1Option 2

Column size0.5 m X 0.5 m0.4 m X 0.4 m0.5 m X 0.5 m0.4 m X 0.4 m

Pile size0.4 m X 0.4m0.4 m X 0.4m0.4 m X 0.4m0.4 m X 0.4m

Pile cap size2.4 m X 2.4 mNot applicable2.4 m X 2.4 mNot applicable

Pile cap thickness0.8 mNot applicable0.8 mNot applicable

column height3.0 m3.0 m

Additional pile height in mNot applicable3.8Not applicable3.8

Column quantity in m30.750.75

Additional pile quantity in m32.4323.04

Pile cap quantity in m33.7446.656

Total quantity in m34.4942.4327.4063.04

Increase in %8501440

Steel Plate thickness for Soft Table top option:The response of a steel plated structure subjected to a dropped drill-collarconsists of global deformation of the plate, combined with local sheardeformation at the impact point. This combined mechanism results in a difficultdesign situation, and existing design formulas show poor agreementwith dropped object tests.Due to lack of knowledge about penetration mechanics related to large massprojectiles in the low velocity range, simplified analytical models for the plugging capacity of steel plated structures subjected to dropped objects are derived from experimental studies. Based on tests carried out and theoretical models, the plugging capacity of a plated structure without stiffeners, subjected to a flat ended dropped object is by the formula (4.17 of Ref 3),

WhereTpu = Critical Impact energyUsu = Critical Strain energyfyo = Static Yield stress of the target materialdp = outer diameter of the projectilero = smallest distance from point of impact to the plate boundaryht = Target plate thicknessMp = Mass of Projectile

The above equation for a plate with stiffeners is simplified as below:Tpu = Usu

In the above equation, the unknown is critical strain energy, Usu, which is area under the force displacement curve, shown in Fig 3.3.1. , for a dropped object deformed axisymmetrically till it penetrates the target plate.uWcu

Fig.3.3.1 Force displacement relationship.

In the above figure, Fso, Wco correspond to force and displacement on the target material at the impact location, when the target material reaches yield limit, and the supports are fully activated.Fso is referred as mechanism force. Fsu is the critical plugging force, when the impacted object punctures the plate. Wcu is the displacement of the target plate at the plugging force.For estimating critical strain energy, Fso, Wco, Fsu, and Wcu are estimated from the closed form solutions. Equations for Fsu, Fso, Ktp are furnished below; Wco is estimated from elastic stiffness of the plate. Detailed steps are given in the embedded calculations file (section 4).

Critical Plugging Force, Fsu:

Where the critical shear stress Tcr is calculated as

Where fsu is ultimate tensile stress

Mechanism force, Fso and Membrane stiffness Ktp are given below

bt, &lt , In the above equations are plate dimensions shown in shown in fig.3.3.2; a and b are derived parameters from bt, lt and dp

Kte, stiffness of the target plate in the elastic zone is obtained as below:

Elastic deflection of the plate w under concentrated load = *Plt2/D

Where is the coefficient which depends on the boundary conditions. D is the flexural rigidity of the plate; Eh3/12(1-2) ;

Elastic Stiffness = P / deformation = D/lt2 ;

Coefficients for various spans, fixed supports, and simple supports are reproduced below:

Stiffener:Stiffener should have higher shear strain energy at its shear capacity, compared to the impact energy. The critical case for stiffener is a direct hit.Strain Energy of a beam = T2/ (2 G) ; Where T is the shear strength of the beam; G is shear modulus;

Structure:Structure should have higher impact strength in axial direction compared to impact energy of the dropped object.

Calculations:Calculations are embedded below:

Comparison of concepts:

Sturctural description:Fig 5.1 shows protective cage. Fig 5.2 shows conventional table top

Fig 5.1 protective cage.

Fig 5.2 Load bearing Table top

Constructability:Sl.No.ContentSoft topElevated cat walkHard topConventional Tabletop

1In Situ WorkLessquantities are lower.More.Quantities are more.

2Foundation WorkNo pilesPiles required under columnsSubstantial work.

3Modules fabrication.Shop fabrication and transporting possible.Not possible

4RigsOK.All rigs are OK.

5Laying of rig trackRequiredNot required.

6Laying of flow linesShall be done prior to laying rig tracksCan be done later

Foundation concept:Foundation for Hard top is concrete piles of column size and shape drilled below the columns.

Foundation for soft top requires laying of base course, compaction and rigid pavement for the rig to move. Typical rig track details are as shown below:

QuantitiesHard TabletopSoft Tabletop

DescriptionUOMQtyDescriptionUOMNo of StrctrsQtyTotal Qty

Ramp - Concrete QtycumStructure - Steel QtyTon1512.2183

Floors - Concrete Qtycum2750Foundation - Concrete Qtym31521.6324

Columnscum150Track - Concrete (per m)m38511.6986

Piling qtycum1425sub base and subgradem3270

Pile Testing/ mob-demob for piling rigs(20%) LS318

RebarMT266

EPC base cost MM$2.8

Opportunities for Improvement:Converting hard impact to soft impactThickness of slab is primarily governed by drop load of BOP stack. Eliminating drop load of BOP stack by administrative measures, or fixing energy absorbing system below BOP stack, during transit to the final location reduces design impact energy substantially (reduction from 251 kJ to 182 kJ). As BOP stacks are few in number, this does not add substantial site work. Another option was to limit the drop height. Finalising rig foot printCurrently hard table top was designed for rig loads with foot print spacing of 5m and 10m.Freezing the type of rig, rig movement zones and drop prone zones reduces quantities for piles and slab.

Conclusions:Hard Table Top:1. A flat slab of 0.8 m thick is required from Penetration resistance and scabbing.2. If piles are extended, thickness of 0.8m is required from pile cap considerations too.3. Column sizes of 0.5 m x 0.5m spaced at 5 m x 5m is feasible for 0.8m thick slab. This is the optimum configuration for columns, when seen in isolation.But, when we consider requirement of piles and pile cap, this is not a cheap option. 4. Pile quantities are greatly influenced by local conditions. The quantities mentioned in 5.4 are for a typical Majnoon site.Soft Table Top1. For soft table top, a plate ofHY80 steel& 12 mm thick is required.2. The structures columns will be of tubular sections or Channel sections welded flange to flange, or I sections ( [] ). Preferred is channel sections welded flange to flange[]3. The support beams beneath the plate are I sections.4. The structure will have Moment connection on one side and bracing on the other side. Alternatively, it can have bracing on either side.5. The structure requires a foundation of 1.5 m x 1.5 m x 0.5 m thickness.

1. References:1. Design for Impact of dropped objects, Offshore Technology Conference paper, OTC-44712. The Design of an Impact resistant roof for platform well head, OTC 39073. Design for Offshore Steel Structures exposed to accidental loads, Report EP 89-0230, August 1988. 4. Concrete Structures under Impact and Impulsive loading, Committee Euro International Du Beton, Bulletin DInformation No 1875. Design Loads of Rotterdam, Design Report6. Impact Behavior Enhancement of Oil Palm Shells Concrete by Geogrid Reinforcement, by ZakariaCheMuda a, Dr. Salah F. A. Sharif a, Tan Yen Lun a.

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Structure which can take rigs of differing foot prints

Documents

Interpretative Report for Phase-3 Lax