case histories on the geotechnical design & construction ... short course - gss.pdf · g&p...

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CASE HISTORIES ON THE CASE HISTORIES ON THE GEOTECHNICAL DESIGN & GEOTECHNICAL DESIGN &

CONSTRUCTION OF THE IPOH CONSTRUCTION OF THE IPOH HOSPITAL EXTENSION HOSPITAL EXTENSION

Cadangan Membina Dan Menyiapkan Cadangan Membina Dan Menyiapkan Blok Wanita, KanakBlok Wanita, Kanak--Kanak dan Pusat Kanak dan Pusat Kardiologi, Hospital Raja Permaisuri Kardiologi, Hospital Raja Permaisuri

Bainun, Ipoh, PerakBainun, Ipoh, PerakBy : Dato’ Ir. Dr. GUE See Sew

Date: 22/09/2014

Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Professionals Sdn BhdG&P Professionals Sdn Bhd

ContentsContents

• Desk Study & Site Visit• Subsurface Investigation (S.I.)• Preliminary Design• Detailed Design• Construction• Approval Process


DESK STUDY & SITE VISIT


Project Location


Project Location

Jalan Hospital


Building LayoutBuilding Layout

Jalan Hospital


Building InformationBuilding Information

• The superstructure consists of a 10-storey tower with :

- 2 floors of elevated car parks- 8 floors of clinical podiums and wards


Site LayoutSite Layout

SITE IS A FLAT AREA


General Geology

Extracted from Geological Map of Perak, Sheet 2-N-5 Ipoh, 1957 published by Geological Survey Department


Site Visit

Direction of Photo Taken


Site Visit



Site Visit



Site Visit



SUBSURFACE INVESTIGATION (S.I.)


Preliminary S.I.

First Stage-Preliminary S.I. (By JKR)•Carried out by Ikram Utara from 9th

January 2010 to 23rd February 2010

•S.I. consists of 6 nos. of Boreholes


Preliminary S.I. Layout

6 nos. Existing BH (First)


BorelogBorelog


Detailed S.I.

Second Stage-Detail S.I.•S.I. has been carried out by Ikram Utara from 26th September 2010 to 9th December 2010

•The S.I. consists of :-– 12 nos. Borehole– 10 nos. Rock Probe– 96 nos. JKR Probe


S.I. Layout12 nos. BH

10 nos. RP

6 nos. Existing BH

Boreholes that show cavities


S.I. During Construction

Third Stage-S.I. During Construction•S.I. has been carried out by Kamalbina Sdn. Bhd. from 1st October 2013•The S.I. consists of :-

– 45 nos. Cavity Probing (Main Building)– 5 nos. Cavity Probing (PPU) (Not carried out yet)


Justification

• Additional S.I. (cavity probing) shall be carried out during construction stage:-– Identify the extent of cavity– More concentrated at cavity area


S.I. Layout

Prelim Boreholes (6 nos)Additional Rock Probes (10 nos)Additional Boreholes (12 nos)Cavity Probe (45 nos)Cavity Detected


Section 2-2



Cross–Section 2-2

Cavities


Section 12-12



Cross–Section 12-12

Cavities


Section D-D



Cross–Section D-D

Cavities


Section J-J



Cross–Section J-JCavities


PRELIMINARY DESIGN


Selection of FoundationSelection of Foundation• General topography

• Magnitude of column loads

• Subsoil profile

• Bearing capacity of ground

• Settlement due to settling platform, disturbance to surrounding neighbors, etc.


Options of FoundationOptions of Foundation

Shallow Foundation

Suitable for Low Rise or

Light Structure

Deep Foundation

Suitable for Medium to High Rise


Selection of PilesSelection of Piles• Types of Piles Available in Market• Installation Method• Ground Conditions (eg Limestone, etc)• Site Conditions & Constraints (eg

Accessibility)• Type and Magnitude of Loading• Development Programme & Cost• etc


Options of Deep FoundationOptions of Deep Foundation• Spun Pile

- Driven- Jack- in

• Bored Pile

• Micro Pile

Not allowed as near to hospital (Noise)


Options of Deep FoundationOptions of Deep Foundation• Jack- in Spun Pile- Overburden too shallow (less than 10D)

• Bored Pile

• Micro Pile

OPTION 1

OPTION 2


Piling Problem in LimestonePiling Problem in Limestone


RecommendationRecommendation

• Detail S.I. for design

• Cavity Probing during construction

• Cavity treatment is required (compaction grout)


DETAILED DESIGN


Detail Design

• Majority of Architectural Layout is Frozen

• Column Loads provided by C&S Engineer


Column Loads DistributionColumn Loads Distribution

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

Column Load (x 103 kN)

0123456789

101112131415161718192021222324252627282930

No.

of C

olum

n

2

6

8

1514

24

2122

1415 15

7

3

1 1 1 1 1 1 1 1


Option 1: Bored Pile Design


Bored Pile DesignBored Pile Design

• Pile Capacity

• Pile Length/Socket Length


Bored Pile CapacityBored Pile Capacity

• Shallow bedrock

• To achieve Structural capacity

Rock Socket Pile


Allowable Structural CapacityAllowable Structural Capacity

QQallall = 0.25 x f= 0.25 x fcucu x Ax Acc

Qall = Allowable pile capacity

fcu = characteristic strength of concrete

Ac = cross sectional area of concrete


Allowable Structural CapacityAllowable Structural Capacity

Size (mm) Working Load

600Type A 500Type B 1100Type C 1600

900 55001050 7500


Allowable Geotechnical CapacityAllowable Geotechnical Capacity

• Fp, Geo (allow) = (fsAs / 1.5) + (fbAb / 3) (Using Partial Safety Factor)

• Fg, Geo (allow) = (fs As + fb Ab) / 2 (Using Global Safety Factor)

Where,fs = Shaft resistance

fb = Base resistanceAs = Surface area of pile shaftAb = Surface area of pile base


Geotechnical CapacityGeotechnical Capacity

• Very Difficult to Ensure Proper Base Cleaning

• Contribution from Base IGNORED


Allowable Geotechnical CapacityAllowable Geotechnical Capacity

• Fp, Geo (allow) = (fsAs / 1.5)

• Fg, Geo (allow) = (fs As / 2

Where,fs = Shaft resistance

fb = Base resistanceAs = Surface area of pile shaftAb = Surface area of pile base

+ (fbAb / 3)

+ fb Ab)fs As / 2


Design AssumptionsDesign Assumptions

• fs(ult) = 2.5 N (for soil)


SPTSPT--NN

30

25

20

15

10

5

0

0 10 20 30

30

25

20

15

10

5

0

Dep

th (m

)

0 10 20 30

SPT-N Value

LegendABH1ABH2ABH3ABH4ABH5ABH6ABH7ABH8ABH9ABH10ABH11ABH12BH1BH2BH3BH4BH5BH6

SPT N = 3


Rock Socket FrictionRock Socket Friction

Working Rock Socket FrictionWorking Rock Socket Friction RQDRQD

300 kPa300 kPa <25%<25%600 kPa600 kPa 2525--70%70%

1000 kPa1000 kPa >70%>70%

The above design values subject to 0.05 x min (UCS, fThe above design values subject to 0.05 x min (UCS, fcu cu ) ) whichever is smallerwhichever is smaller

Reference: Neoh (1998)Reference: Neoh (1998)


RQD ValuesRQD Values

30

25

20

15

10

5

0

0 10 20 30 40 50 60 70 80 90 100

Rock Quality Designation, RQD (%)

30

25

20

15

10

5

0D

epth

bel

ow G

roun

d Le

vel (

mbg

l)

Legend

ABH1ABH2ABH3ABH4ABH5ABH6ABH7ABH8ABH9ABH10ABH11ABH12RP1RP2RP(2A)RP3RP4RP5RP6RP7RP8RP9RP10BH1BH2BH3BH4BH5BH6

0 10 20 30 40 50 60 70 80 90 100


UCS ValuesUCS Values

30

25

20

15

10

5

0

0 10 20 30 40 50 60 70 80 90 100

Unconfined Compressive Strength, UCS (MPa)

30

25

20

15

10

5

0

Dep

th b

elow

Gro

und

Leve

l (m

bgl)

Legend

ABH1ABH2ABH3ABH4ABH5ABH6ABH7ABH8ABH9ABH10ABH11ABH12RP1RP2RP(2A)RP3RP4RP5RP6RP7RP8RP9RP10BH1BH2BH3BH4BH5BH6

0 10 20 30 40 50 60 70 80 90 100


Rock Socket FrictionRock Socket Friction

Working Rock Socket FrictionWorking Rock Socket Friction RQDRQD

300 kPa300 kPa <25%<25%600 kPa600 kPa 2525--70%70%

1000 kPa1000 kPa >70%>70%

The Rock Socket Friction to be confirmed by The Rock Socket Friction to be confirmed by Instrumented Pile TestInstrumented Pile Test


Rock Socket LengthRock Socket Length

• L = Structural Capacity / 600kPa x π x D

Where,L = Rock Socket LengthD = Diameter of Bored Pile


Rock Socket LengthRock Socket Length

Bore Pile Size Rock Socket Length

600 mm

Type A 0.5mType B 1.0mType C 1.5m

900 mm 3.5m1050 mm 4.0m


φφ600mm Bored Pile600mm Bored Pile


Option 2 :Micro Pile Design


Micro Pile DesignMicro Pile Design• Design based on 300mm pile size

• Reinforcement : API Pipe Grade N80 (177.8mm outer diameter and 10.36mm thickness)

• Rock Socket Pile

• Only Shaft Friction Considered

• End Bearing IGNORED


Structural CapacityStructural CapacityP Structural (ultimate) = fy * As

OR

P Structural (ultimate) = 0.4*(fcu*Ac) + 0.75*(fy * As) (as short column based on cl.3.8.4.3: BS 8110: 1985)

OR

P Structural (ultimate) = 0.5 * fy * (As + Ec/Es * Ac) (as composite section by strain compatibility based on cl.7.4.6.3.1: BS 8004: 1986)

Where fy = Yield stress of API pipe, 552 N/mm2 for Grade N80As = Area of API pipefcu = Grade of grout

Ac = Cross-sectional area of groutEc = Elastic Modulus of ConcreteEs = Elastic Modulus of Steel


Micro Pile CapacityMicro Pile Capacity

• FOS for Structural Capacity = 2.0 (based on Table 2: BS 8081: 1989)

• Allowable Structural Capacity 1500 kN


Micro Pile LengthMicro Pile Length• Grout/Rock bond interface, FOS = 3.0

(Table 2: BS 8081:1989)

• Ultimate Grout/Rock bond stress=1.8N/mm2

• Reinforcement/Grout interface, FOS = 3.0(Table 2: BS 8081:1989)

• Ultimate Reinforcement/Grout bond stress=1.9N/mm2

(Table 3.28 :BS8110: 1985)


Micro Pile LengthMicro Pile Length

• Rock Socket Length = 3m


Cost Comparison


CHEAPER!

Cost ComparisonCost Comparison

Bored Pile Micro Pile

Total Nos. Of Pile

Total Cost

351 1483

RM5.5 Million RM8 Million

ADOPTED


Cavity Treatment


Importance of Cavity TreatmentApplication of Building Load

Roof of Cavity starts to Crack …


Cavity Treatment

• Compaction Grouting is proposed for the cavity treatment.

• 1: 3 Cement & Sand

• Pressure not less than 7 MPa


Compaction Grouting

The tremie pipe to transferthe mortar into cavity

The mortar from the mixture will pump into the cavity using hydraulic pump


CONSTRUCTION


Bored PilesBORED BORED PILING PILING

MACHINEMACHINE

BG22


DrillingDrilling


Lower Lower ReinforcementReinforcement


Place Place Tremie Tremie

ConcreteConcrete


Completed BoredpileCompleted Boredpile


Definition of Rock Socket

• Definition of Rock Socket• Point Load Test

3 SETS POINT LOAD TEST AT EVERY 1m

CHANGE TOOLS

IS(50) 3 MPA

RECOVERED ROCK MORE THAN 70%


UCS vs IUCS vs IS(50)S(50)


Criteria of Rock Socket Length at Criteria of Rock Socket Length at Cavity AreaCavity Area

IF V1<2.5H1

IF V2<2.5H2

Rock SocketH1 H2

√√ √√ √√ √√

XX √√ XX √√√√ XX XX XX

XX XX XX XX

V1 and V2 (Treated Cavity) Not Considered As Rock Socket


Construction issuesConstruction issues

• No chiseling

• Adjustment of rock sockets


ADJUSTMENT OF ROCK SOCKET LENGTH BASED ON INPUT DURING CONSTRUCTION

Designed socket length Limestone Bedrock

Rock socketed

piles

Stable rock zone

Sacrificial socket length

Designed socket length

Potentially unstable

rock zone


Inclined limestone bedrock

Temporary casing

Collapse of Loose Soil (Slime)

Rock Socket

Rock

Soil

Soft Toe

COLLAPSE OF LOOSE SOIL (SLIME) SURROUNDING THE BORED HOLE



Inclined limestone bedrock

Temporary casing

No collapse of loose soil (slime) surrounding the

bored bole

Rock Socket

Rock

Soil

PERFORMANCE OF MODIFIED CORING TOOL


Verification TestVerification Test


Verification Test

• Preliminary Instrumented Pile Test• Maintained Load Test• Sonic Logging• Pile Integrity


Pile TestsPile Tests


Instrumented Pile Load TestInstrumented Pile Load Test

Extensometer

Vibrating Wire Strain

Gauges



• 1 No. of Test • Purpose - To test pile capacity contributed from friction



• Carried out on 12th December 2013• Pile diameter : 1050mm• Pile Working Load : 7500 kN• Test failed at 2.5 times WL• Rock socket length is confirmed

maintained


Static Load TestStatic Load Test

• No. of Test - 4 nos.• Purpose - To test pile capacity

(cannot differentiate between the base and friction contribution)


Static Load TestStatic Load Test• Failure load:

Continuous settlement at constant load• JKR Specification:

The tested pile deemed to have failed if:– The residual settlement after removal of the Test

Load exceeds 6.5mm; or– The total settlement under the Design Load

exceeds 12.5mm; or– The total settlement under twice the Design

Load exceeds 38.0mm, or 10% of pile diameter/width, whichever is the lower value


Static Load TestStatic Load Test“The residual settlement after removal of

the Test Load exceeds 6.5mm”

• Not specific on which load (1WL or 2WL)• Test Load shall only refer to 1WL

•Inappropriate to limit residual settlement at twice design load


Static Load TestStatic Load Test

Load

Settlement, ρ

Failure Load

1WL

Continuous settlement at constant load

12.5mm6.5mm

At failure load (2WL) should not limit ρ andmention on residual ρ


Static Load TestStatic Load Test• Most standard not consider residual ρ,

except Australian Standard AS 2159 (Piling - Design and Installation)

• AS 2159-1995– After remove serviceability load: 7mm– After remove 1.5 design action effect: 30mm

• AS 2159-2009– After remove serviceability load: Max 0.01d, 5 (mm)– After remove ultimate load: 10 + 0.05d (mm)

Note: d is pile diameter


Pile Integrity TestPile Integrity Test

• No. of Test - 28 nos.• Purpose - To verify concrete quality


Sonic Logging TestSonic Logging Test

• No. of Test – 28 nos.• Purpose - To verify concrete quality


SinkholeSinkhole


Sinkhole Encountered During Sinkhole Encountered During ConstructionConstruction

Sinkhole 1

Sinkhole 2

Sinkhole 3


Sinkhole 1 (Near CP20)

Sinkhole 5-6m Dia. With 4-5m Depth

Date :22 November 2013

Sinkhole



Sinkhole 4.2m Dia. With 1.5m Depth

Date :17th December 2013



Sinkhole 2m

Sinkhole 2m Dia. With 2m Depth

Date :23rd December 2013


Rectification works Rectification works

2. Backfilled with sand materials

1. Carry out cavity treatment


Rectification works

Additional Cavity Probing

3. Carry out Cavity Probing to ensure no cavity/cavity treated

CP 20A

CP 20B

CP 20D

CP 20C

3a. 4 nos. Cavity Probing at Sinkhole 1

Sinkhole1


Rectification works3b. Additional 3 nos. Cavity Probing at Sinkhole 2

(Yet to be carried out)

CP 40A

CP 40BCP 40C


Rectification works3c. Additional 10 nos. Cavity Probing at Sinkhole 3

Sinkhole 3


APPROVAL PROCESSAPPROVAL PROCESS


Approval ProcessApproval Process

ContractorConsulting Engineer

PTB (Penyelia Tapak Bina)

JKR HQ

Submission

Recommendation for Approval

Seek for Approval / Advise

Approval / Advise

ApprovalImplication:•Time (2 to ≥4 weeks)

Issue:•Delay•Claim for delay?


Approval ProcessApproval Process

• SO to approve if:– Work is within the contract– Work is approved by JKR


Rock Socket Lengthening Rock Socket Lengthening

• Lengthening in cavity

• Decision: How long? 1 or 3 working days

• Issue: Delay causes collapse of drilled hole


Role of Client and ConsultantRole of Client and Consultant

• Client (JKR HODT/HOPT) and Consultant shall:– Ensure quality of works

• Inspection– Facilitate the construction for completion on

time– Control construction cost within budget


Thank YouThank You


Q & A SessionQ & A Session

case histories on the geotechnical design & construction ... short course - gss.pdf · g&p...

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