L 16 pilfoundation

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L 16 pilfoundation

  1. 1. PILED FOUNDATIONDESIGN & CONSTRUCTION By Ir. Dr. Gue See Sew http://www.gnpgeo.com.my
  2. 2. ContentsOverviewPreliminary StudySite Visit & SI PlanningPile DesignPile Installation MethodsTypes of Piles
  3. 3. Contents (Cont’d)Piling SupervisionPile DamagePiling ProblemsTypical Design and Construction IssuesMyths in PilingCase HistoriesConclusions
  4. 4. Overview
  5. 5. What is a Pile FoundationIt is a foundation system thattransfers loads to a deeperand competent soil layer.
  6. 6. When To Use Pile Foundations• Inadequate Bearing Capacity of Shallow Foundations• To Prevent Uplift Forces• To Reduce Excessive Settlement
  7. 7. PILE CLASSIFICATIONFriction Pile– Load Bearing Resistance derived mainly from skin frictionEnd Bearing Pile– Load Bearing Resistance derived mainly from base
  8. 8. Friction PileOverburden Soil Layer
  9. 9. End Bearing PileOverburden SoilRock / Hard Layer
  10. 10. Preliminary Study
  11. 11. Preliminary StudyType & Requirements of SuperstructureProposed Platform Level (ie CUT or FILL)Geology of AreaPrevious Data or Case HistoriesSubsurface Investigation PlanningSelection of Types & Size of Piles
  12. 12. Previous Data & Case Histories Existing Existing Proposed DevelopmentDevelopment Development B A Only Need Minimal Number of Boreholes Bedrock Profile
  13. 13. Challenge The Norm Thru Innovation To Excel
  14. 14. SELECTION OF PILESFactors Influencing Pile Selection – Types of Piles Available in Market (see Fig. 1) – Installation Method – Contractual Requirements – Ground Conditions (eg Limestone, etc) – Site Conditions & Constraints (eg Accessibility) – Type and Magnitude of Loading – Development Program & Cost – etc
  15. 15. TYPE OF PILES DISPLACEMENT PILES NON-DISPLACEMENT PILES TOTALLY PREFORMED PILES DRIVEN CAST IN-PLACE PILES Bored piles (A ready-made pile is driven or jacked (a tube is driven into ground to Micro piles into the ground) form void) Hollow Solid Concrete Tube Steel Tube Small displacement Closed ended tube concreted Closed ended tube Open ended tubeSteel Pipe Concrete Spun Piles with tube left in extracted while position concreting (Franki) Concrete Steel H-piles Bakau piles (small displacement) Treated timber pile Precast R.C. Precast prestressed piles piles FIG 1: CLASSIFICATION OF PILES
  16. 16. PREFORMED PILES LEGEND : STEEL PIPE PILES TYPE OF PILE AUGERED PILES INDICATES THAT THE PILE TYPE IS STEEL H PILES JACKED PILES 8 TIMPER PILES BORED PILES BAKAU PILES MICROPILES SUITABLE SPUN PILES PSC PILES DESIGN RC PILES INDICATES THAT THE PILE TYPE IS CONSIDERATIONS x NOT SUITABLE ? ? ? ? x ? INDICATES THAT THE USE OF PILE <100 KN a a a a a ? ? x ? TYPE IS DOUBTFUL OR NOT COST 100-300 a a a a a a a a SCALE OF LOAD EFFECTIVE UNLESS ADDITIONAL (STRUCTURAL) 300-600 ? a a a a a a a a a a 600-1100 x ? a a a a a ? a a ? MEASURES TAKEN COMPRESSIVE LOAD PER COLUMN 1100-2000 x ? a a a a a ? a a ? 2000-5000 x x a a a a a ? a a ? 5000-10000 x x a a a a a x a a x >10000 x x ? a a a a x a ? x <5m ? ? ? ? ? ? ? x a a ? a a a a a a a ? a a a BEARING TYPE 5-10m MAINLY END -BEARING 10-20m ? ? a a a a a a a a a (D=Anticipated depth of bearing) 20-30m x x a a a a a a a a a 30-60m x x a a a a a a a ? a MAINLY FRICTION a a a a a ? a a a ? a PARTLY FRICTION + PARTLY END BEARING a a a a a a a a a ? a LIMESTON FORMATION ? ? ? ? ? a a a ? a a BEARING TYPE OF LAYER WEATHERED ROCK / SOFT ROCK x x a a a a a ? a a ? ROCK (RQD > 70%) x x ? ? ? a a ? a a ? x ?GEOTECHNICAL DENSE / VERY DENSE SAND a a a a a a a a a SOFT SPT < 4 a a a a a a a a a ? a M. STIFF SPT = 4 - 15 a a a a a a a a a a a TYPE OF INTERMEDIATE LAYER COHESIVE SOIL V. STIFF SPT = 15 - 32 ? a a a a a a a a a a HARD SPT > 32 x ? a a a a a a a a a LOOSE SPT < 10 a a a a a a a a a a a M. DENSE SPT = 10 - 30 ? a a a a a a a a a a COHESIVELESS SOIL DENSE SPT = 30 - 50 x ? a a a a a a a a a V. DENSE SPT > 50 x x a a a a a ? a a ? S < 100 mm x ? a a a a a a a a ? SOIL WITH SOME BOULDERS / 100-1000mm x x ? ? ? a a ? a a x COBBLES (S=SIZE) 1000-3000mm x x ? ? ? ? ? ? ? a x >3000mm x x ? ? ? ? ? ? ? a x GROUND ABOVE PILE CAP a a a a a a a a a a a WATER BELOW PILE CAP x a a a a a a a a a a NOISE + VIBRATION; COUNTER MEASURES ? ? ? ? ? a a a a a aENVIRONME REQUIRED NT PREVENTION OF EFFECTS ON ADJOINING ? ? ? ? ? ? ? ? a a a STRUCTURESUNIT COST (SUPPLY & INSTALL) RM/TON/M 0.5-2.5 0.3-2.0 1.0-3.5 1-2 0.5-2 1.5-3 1-2.5 FIG 2 : PILE SELECTION CHART
  17. 17. Pile Selection Based on CostDetails: 250mm Spun Piles 300mm Spun Piles Micropile Total Points 83 70 70 Average Length 9m 9m 9m Average Rock Socket Length - - 2.5mIndicative Rates : Mob & Demob RM 50,000.00 RM 50,000.00 RM 20,000.00 Supply RM 33.00 / m RM 42.00 / m - Drive RM 30.00 / m RM 32.00 / m - Cut Excess, Dispose + Starter Bars RM 200.00 / Nos RM 200.00 / Nos - Movement - - RM 200.00 / Nos Drilling in Soil - - RM 110.00 / m Drilling in Rock - - RM 240.00 / m API Pipe - - RM 120.00 / m Grouting - - RM 85.00 / m Pile Head - - RM 150.00 / NosEst. Ave. Cost Per Point RM 967.00 / Nos RM 1,066.00 / Nos RM 4,297.50 / NosEst. Foundation Cost RM 190,261.00 RM 184,620.00 RM 380,825.00 √
  18. 18. Site Visit and SI Planning
  19. 19. Site VisitThings To Look For … Accessibility & Constraints of Site Adjacent Structures/Slopes, Rivers, Boulders, etc Adjacent Activities (eg excavation) Confirm Topography & Site Conditions Any Other Observations that may affect Design and Construction of Foundation
  20. 20. Subsurface Investigation (SI) PlanningProvide Sufficient Boreholes to get Subsoil ProfileCollect Rock Samples for Strength Tests (eg UCT)In-Situ Tests to get consistency of ground (eg SPT)Classification Tests to Determine Soil TypeProfileSoil Strength Tests (eg CIU)Chemical Tests (eg Chlorine, Sulphate, etc)
  21. 21. Typical Cross-Section at Hill Site Ground Level Hard Material Level Very Hard Material Level Bedrock Level Groundwater Level
  22. 22. EXISTING CROSS SECTION GROUND LEVEL BH BH C’1, ø’1 ’ r C ’ 2, ø 2 edW T Laye BH Perch Cla y ey Seepage C’3, ø’3Water Table
  23. 23. Placing Boreholes in Limestone Areas Stage 1 : Preliminary S.I. - Carry out geophysical survey (for large areas) Stage 2: Detailed S.I. - Boreholes at Critical Areas Interpreted from Stage 1 Stage 3: During Construction - Rock Probing at Selected Columns to supplement Stage 2
  24. 24. Pile Design
  25. 25. PILE DESIGNAllowable Pile Capacity is the minimum of : 1) Allowable Structural Capacity 2) Allowable Geotechnical Capacity a. Negative Skin Friction b. Settlement Control
  26. 26. PILE DESIGNStructural consideration• Not overstressed during handling, installation & in service for pile body, pile head, joint & shoe. • Dimension & alignment tolerances (common defects?) • Compute the allowable load in soft soil (<10kPa) over hard stratum • Durability assessment
  27. 27. Pile Capacity Design Structural Capacity Qall = Allowable pile capacity Concrete Pile fcu = characteristic strength Qall = 0.25 x fcu x Ac of concrete fs = yield strength of steel Ac = cross sectional area of Steel Pile concrete Qall = 0.3 x fy x As As = cross sectional area of steel Prestressed Concrete PileQall = 0.25 (fcu – Prestress after loss) x Ac
  28. 28. Pile Capacity Design Geotechnical CapacityCollection of SI Data Depth Vs SPT-N Blow Count 0 50 100 150 200 250 300 350 400 0 0 2 4 2 6 Depth (m) 8 Upper Bound 4 10 12 6 14 16 8 18 20 Design Line 22 Lower 10 (Moderately Bound Conservative) 24 26 12 0 50 100 150 200 250 300 350 400 SPT Blow Count per 300mm Penetration
  29. 29. Pile Capacity Design Geotechnical Capacity Collection of SI Data Depth Vs SPT-N Blow Count Depth Vs SPT-N Blow Count 0 50 100 150 200 250 300 350 400 0 50 100 150 200 250 300 350 400 0 0 0 0 2 2 4 4 2 2 6 6 8 Depth (m) 8 Upper BoundDepth (m) 4 4 10 10 12 12 6 6 14 14 16 16 8 8 18 Design Line 18 Upper Bound Lower 20 20 Bound 22 10 22 Lower 10 Bound Design Line 24 24 26 12 26 12 0 50 100 150 200 250 300 350 400 0 50 100 150 200 250 300 350 400 SPT Blow Count per 300mm Penetration SPT Blow Count per 300mm Penetration
  30. 30. Pile Capacity Design Geotechnical Capacity• Piles installed in a group may fail: • Individually • As a block
  31. 31. Pile Capacity Design Geotechnical Capacity• Piles fail individually • When installed at large spacing
  32. 32. Pile Capacity Design Geotechnical Capacity• Piles fail as a block • When installed at close spacing
  33. 33. Pile Capacity DesignSingle Pile Capacity
  34. 34. Pile Capacity Design Factor of Safety (FOS)Factor of Safety (FOS) is requiredfor Natural variations in soil strength & compressibility
  35. 35. Pile Capacity Design Factor of Safety (FOS)Factor of Safety is(FOS) required for Different degree of Load mobilisation for shaft qsmob & for tip qbmob ≈ 5mm Settlement
  36. 36. Pile Capacity Design Factor of Safety (FOS)Partial factors of safety for shaft & basecapacities respectively For shaft, use 1.5 (typical) For base, use 3.0 (typical) Qall = ΣQsu + Qbu 1.5 3.0
  37. 37. Pile Capacity Design Factor of Safety (FOS)Global factor of safety for total ultimatecapacity Use 2.0 (typical) Qall = ΣQsu + Qbu 2.0
  38. 38. Pile Capacity Design Factor of Safety (FOS)Calculate using BOTH approaches(Partial & Global)Choose the lower of the Qall values
  39. 39. Pile Capacity Design Single Pile Capacity Qu = ultimate bearing capacity Qu = Qs + Qb Qs = skin friction Qb = end bearingOverburden Soil Layer
  40. 40. Pile Capacity DesignSingle Pile Capacity : In Cohesive Soil Qsu Qbu Qu = α.sus.As + sub.Nc.Ab Qu = Ultimate bearing capacity of the pile a = adhesion factor (see next slide) sus = average undrained shear strength for shaft As = surface area of shaft sub = undrained shear strength at pile base Nc = bearing capacity factor (taken as 9.0) Ab = cross sectional area of pile base
  41. 41. Pile Capacity DesignSingle Pile Capacity: In Cohesive SoilAdhesion factor (α) – Shear strength (Su) (McClelland, 1974) 1.0 Preferred Design Line 0.8 0.6 Cα/Su 0.4 Adhesion Factor 0.2 0 25 50 75 100 125 150 175 Su (kN/m2)
  42. 42. Meyerhof Fukuoka su = fsu=2.5N fsu=α.suSPT N (0.1+0.15N)*50 α (kPa) (kPa) (kPa) 0 0 5 1 5 1 2.5 12.5 1 12.5 5 12.5 42.5 0.7 29.75 10 25 80 0.52 41.6 15 37.5 117.5 0.4 47 20 50 155 0.33 51.15 30 75 230 0.3 69 40 100 305 0.3 91.5
  43. 43. Pile Capacity Design Single Pile Capacity: In Cohesive Soil Correlation Between SPT N and fsu fsu vs SPT N 110 100 90 80 70 60(kPa) fsu 50 40 30 20 10 0 0 5 10 15 20 25 30 35 40 45 SPT N Meyerhof Fukuoka
  44. 44. Pile Capacity Design Single Pile Capacity: In Cohesive Soil Values of undrained shear strength, su can be obtained from the following: Unconfined compressive test Field vane shear test Deduce based on Fukuoka’s Plot (minimum su ) Deduce from SPT-N values based on MeyerhofNOTE: Use only direct field data for shaft friction predictioninstead of Meyerhof
  45. 45. Pile Capacity Design Single Pile Capacity: In Cohesive SoilModified Meyerhof (1976): Ult. Shaft friction = Qsu ≅ 2.5N (kPa) Ult. Toe capacity = Qbu ≅ 250N (kPa) or 9 su (kPa) (Beware of base cleaning for bored piles – ignore base capacity if doubtful)
  46. 46. Pile Capacity DesignSingle Pile Capacity: In Cohesionless SoilModified Meyerhof (1976): Ult. Shaft Friction = Qsu ≅ 2.0N (kPa) Ult. Toe Capacity= Qbu ≅ 250N – 400N (kPa)
  47. 47. Pile Capacity Design Load (kN) 0 0 100 100 200 200 300 300 400 400 500 500 0 0 0 0 4 4 4 4 ΣQsu 8 8 Qbu 8 8 Depth (m) ΣQsu + Qbu 12 12 12 12 ΣQsu + Qbu ΣQsu + Qbu 1.5 3.0 2.0 16 16 16 16 20 20 20 20 0 0 200 200 400 400 600 600
  48. 48. Pile Capacity Design Block Capacity
  49. 49. Pile Capacity Design Block Capacity:In Cohesive Soil Qu = 2D(B+L) s + 1.3(sb.Nc.B.L)WhereQu= ultimate bearing capacity of pile groupD = depth of pile below pile cap levelB = width of pile groupL = length of pile groups = average cohesion of clay around groupsb = cohesion of clay beneath groupNc= bearing capacity factor = 9.0(Refer to Text by Tomlinson, 1995)
  50. 50. Pile Capacity DesignBlock Capacity: In Cohesionless Soil No risk of group failureif FOS of individual pile is adequate
  51. 51. Pile Capacity Design Block Capacity: On RockNo risk of block failureif the piles are properly seated in the rock formation
  52. 52. Pile Capacity DesignNegative Skin Friction (NSF)
  53. 53. Pile Capacity Design Negative Skin FrictionCompressible soil layer consolidateswith time due to: Surcharge of fill Lowering of groundwater table
  54. 54. Pile Capacity Design Negative Skin Friction Hf FillOGL 0 1 2 3 Month ρs Clay
  55. 55. Pile Capacity Design Negative Skin FrictionPile to length (floating pile) Pile settles with consolidating soil NO NSF
  56. 56. Pile Capacity Design Negative Skin FrictionPile to set at hard stratum (end-bearing pile) Consolidation causes downdrag forces on piles as soil settles more than the pile
  57. 57. Pile Capacity Design Negative Skin FrictionWARNING: No free fill by the contractor to avoid NSF
  58. 58. Effect of NSF …Reduction of Pile Carrying Capacity
  59. 59. Effect of NSF …
  60. 60. NSF Preventive Measures Avoid Filling Carry Out Surcharging Sleeve the Pile Shaft Slip Coating Reserve Structural Capacity for NSF Allow for Larger Settlements
  61. 61. Pile Capacity Design Negative Skin FrictionQall = (Qsu/1.5 + Qbu/3.0) Qall = (Qsu/1.5 + Qbu/3.0) - Qneg FL OGL Sand OGL Clay Clay Qneg Qsu Qsu Sand Sand Qba Qba
  62. 62. Pile Capacity Design Negative Skin Friction Increased Pile Axial LoadCheck: maximum axial load < structural pile SPT-N (Blows/300mm) Settlement (mm) Axial Compression Force (kN)capacity 0 0 10 20 30 40 50 70 60 50 40 30 20 10 100 0 -100 -200 -300-400-500-600 -700 -800 -900-1000 0 5 10 15 Depth (m, bgl) Settlement Curves & 20 Axial Compression Force 14 May 98 15 May 98 18 May 98 25 21 May 98 04 Jun 98 09 Jun 98 30 19 Jun 98 02 Jul 98 13 Jul 98 Maximum Borehole 35 BH-1 Datum = 36.300m axial load BH-2 40
  63. 63. Pile Capacity Design Factor of Safety (FOS) Without Negative Skin Friction: QultAllowable working load FOSWith Negative Skin Friction:Allowable working load Qult (Qneg + etc) FOS
  64. 64. Pile Capacity Design Static Pile Load Test (Piles with NSF)• Specified Working Load (SWL) = Specified foundation load at pile head• Design Verification Load (DVL) = SWL + 2 Qneg• Proof Load: will not normally exceed DVL + SWL
  65. 65. Pile Settlement Design
  66. 66. Pile Settlement Design In Cohesive SoilDesign for total settlement &differential settlement for designtoleranceIn certain cases, total settlement not an casesissueDifferential settlement can causedamage to structures
  67. 67. Pile Settlement Design In Cohesive Soil Pile Group Settlement in Clay = Immediate / ConsolidationElastic Settlement + Settlement
  68. 68. Pile Settlement Design In Cohesive SoilIMMEDIATE SETTLEMENT μ1μ 0 qn B by Janbu, Bjerrum and pi = Kjaernsli (1956) Eu Where pi = average immediate settlement qn= pressure at base of equivalent raft B = width of the equivalent raft Eu= deformation modulus μ1, μ0= influence factors for pile group width, B at depth D below ground surface
  69. 69. Pile Settlement Design In Cohesive SoilIMMEDIATE SETTLEMENT μ1 μ0Influence factors (afterJanbu, Bjerrum andKjaernsli, 1956)
  70. 70. Pile Settlement Design In Cohesive SoilCONSOLIDATION SETTLEMENT As per footing (references given later)
  71. 71. Pile Settlement Design On RockNo risk of excessive settlement
  72. 72. Pile Installation Methods
  73. 73. PILE INSTALLATION METHODS•Diesel / Hydraulic / Drop Hammer Driving•Jacked-In•Prebore Then Drive•Prebore Then Jacked In•Cast-In-Situ Pile
  74. 74. Diesel Drop Hammer Hydraulic Hammer Driving Driving
  75. 75. Jacked-In Piling
  76. 76. Jacked-In Piling (Cont’d)
  77. 77. Cast-In-SituCast-In-Situ Piles(Micropiles)(Micropiles)
  78. 78. Types of Piles
  79. 79. TYPES OF PILES•Treated Timber •Steel PilesPiles •Boredpiles•Bakau Piles •Micropiles•R.C. Square Piles •Caisson Piles•Pre-Stressed Concrete Spun Piles
  80. 80. R.C. Square PilesSize : 150mm to 400mmLengths : 3m, 6m, 9m and 12mStructural Capacity : 25Ton to 185TonMaterial : Grade 40MPa ConcreteJoints: WeldedInstallation Method : –Drop Hammer –Jack-In
  81. 81. RCSquare Piles
  82. 82. Pile Marking
  83. 83. Pile Lifting
  84. 84. Pile Fitting to Piling Machine
  85. 85. PilePositioning
  86. 86. Pile Joining
  87. 87. Considerations in Using RC Square Piles … •Pile Quality •Pile Handling Stresses •Driving Stresses •Tensile Stresses •Lateral Loads •Jointing
  88. 88. Pre-stressed Concrete Spun PilesSize : 250mm to 1000mmLengths : 6m, 9m and 12m (Typical)Structural Capacity : 45Ton to 520TonMaterial : Grade 60MPa & 80MPa ConcreteJoints: WeldedInstallation Method : –Drop Hammer –Jack-In
  89. 89. Spun Piles
  90. 90. Spun Piles vs RC Square Piles Spun Piles have … •Better Bending Resistance •Higher Axial Capacity •Better Manufacturing Quality •Able to Sustain Higher Driving Stresses •Higher Tensile Capacity •Easier to Check Integrity of Pile •Similar cost as RC Square Piles
  91. 91. Steel H PilesSize : 200mm to 400mLengths : 6m and 12mStructural Capacity : 40Ton to 1,000TonMaterial : 250N/mm2 to 410N/mm2 SteelJoints: WeldedInstallation Method : –Hydraulic Hammer –Jack-In
  92. 92. Steel H Piles
  93. 93. Steel H Piles (Cont’d)
  94. 94. Steel H Piles Notes… •Corrosion Rate •Fatigue •OverDriving
  95. 95. OverDrivingof Steel Piles
  96. 96. Large Diameter Cast-In-Situ Piles (Bored Piles)Size : 450mm to 2mLengths : VariesStructural Capacity : 80Ton to 2,300TonsConcrete Grade : 20MPa to 30MPa (Tremie)Joints : NoneInstallation Method : Drill then Cast-In-Situ
  97. 97. Drilling Borepile ConstructionOverburden Soil LayerBedrock
  98. 98. Advance Drilling Borepile ConstructionOverburden Soil LayerBedrock
  99. 99. Drilling & Advance Borepile Construction CasingOverburden Soil LayerBedrock
  100. 100. Drill to Bedrock Borepile ConstructionOverburden Soil LayerBedrock
  101. 101. Lower Borepile Construction Reinforcement CageOverburden Soil LayerBedrock
  102. 102. Lower Tremie Borepile Construction ChuteOverburden Soil LayerBedrock
  103. 103. Pour Tremie Borepile Construction ConcreteOverburden Soil LayerBedrock
  104. 104. Completed Borepile Construction BorepileOverburden Soil LayerBedrock
  105. 105. Bored Pile ConstructionBORED PILING MACHINE BG22
  106. 106. Rock Reamer Rock AugerCleaning Bucket
  107. 107. Rock ChiselHarden Steel
  108. 108. Bored Pile ConstructionDRILLING EQUIPMENT Coring bucket Soil auger Cleaning bucket
  109. 109. Bored Pile ConstructionBENTONITE PLANT Desanding Machine Water Tank Mixer Slurry Tank
  110. 110. Drilling
  111. 111. LowerReinforcement
  112. 112. Place TremieConcrete
  113. 113. Completed Boredpile
  114. 114. Borepile Cosiderations…•Borepile Base Difficult to Clean•Bulging / Necking•Collapse of Sidewall•Dispute on Level of Weathered Rock
  115. 115. MicropilesSize : 100mm to 350mm DiameterLengths : VariesStructural Capacity : 20Ton to 250TonMaterial : Grade 25MPa to 35MPa Grout N80 API Pipe as ReinforcementJoints: NoneInstallation Method : –Drill then Cast-In-Situ –Percussion Then Cast-In-Situ
  116. 116. Cast-In-Situ Piles(Micropiles)
  117. 117. TYPES OF PILE SHOES •Flat Ended Shoe •Oslo Point •Cast-Iron Pointed Tip •Cross Fin Shoe •H-Section
  118. 118. Cross Fin Shoe
  119. 119. Oslo Point Shoe
  120. 120. Cast Iron Tip Shoe
  121. 121. H-Section Shoe
  122. 122. Piling Supervision
  123. 123. Uniform Building By Law (UBBL)1984
  124. 124. PILING SUPERVISION•Ensure That Piles Are Stacked Properly•Ensure that Piles are Vertical During Driving•Keep Proper Piling Records•Ensure Correct Pile Types and Sizes are Used•Ensure that Pile Joints are Properly Welded with NO GAPS•Ensure Use of Correct Hammer Weights and Drop Heights
  125. 125. PILING SUPERVISION (Cont’d)•Ensure that Proper Types of Pile Shoes are Used.•Check Pile Quality•Ensure that the Piles are Driven to the Required Lengths•Monitor Pile Driving
  126. 126. FAILURE OF PILING SUPERVISIONFailing to Provide Proper Supervision WILL Result in Higher Instances of Pile Damage & Wastage
  127. 127. Pile Damage
  128. 128. Driven concrete piles are vulnerable to damages by overdriving.
  129. 129. Damage to Timber Pile
  130. 130. WeakTimber Joint
  131. 131. Damage To RC Pile Toe
  132. 132. Damage to RC Pile Head
  133. 133. Damage to RC Piles
  134. 134. Damage to RC Piles – cont’d
  135. 135. Tilted RC Piles
  136. 136. Damage to Steel Piles
  137. 137. Damaged Steel Pipe Piles
  138. 138. Detection of Pile Damage Through Piling Records
  139. 139. Piling Problems
  140. 140. Piling Problems – Soft Ground
  141. 141. Piling Problems – Soft Ground Ground heave due topressure relief at base & surcharge near excavation Pile tilts & moves/walks
  142. 142. Piling Problems – Soft Ground
  143. 143. Piling in Kuala Lumpur LimestoneImportant Points to Note: • Highly Irregular Bedrock Profile • Presence of Cavities & Solution Channels • Very Soft Soil Immediately Above Limestone BedrockResults in … • High Rates of Pile Damage • High Bending Stresses
  144. 144. Piling Problems in Typical Limestone Bedrock
  145. 145. Piling Problems – Undetected Problems
  146. 146. Piling Problems – Coastal Alluvium
  147. 147. Piling Problems – Defective Piles Defect due to poorSeriously damaged workmanship of pilepile due to severe castingdriving stress in softground (tension)
  148. 148. Piling Problems – Defective Piles Problems of defective pile headDefective pile shoe & overdriving!
  149. 149. Piling Problems – Defective Piles Non- chamfered corners Cracks& fractured
  150. 150. Piling Problems – Defective Piles Pile head defect due to hard driving or and poor workmanship
  151. 151. Piling Problem - Micropiles Sinkholes caused by installation method- dewatering?
  152. 152. Piling in Fill GroundImportant Points to Note: •High Consolidation Settlements If Original Ground is Soft •Uneven Settlement Due to Uneven Fill Thickness •Collapse Settlement of Fill Layer If Not Compacted ProperlyResults in … •Negative Skin Friction (NSF) & Crushing of Pile Due to High Compressive Stresses •Uneven Settlements
  153. 153. Typical Design and Construction Issues #1Issue #1Pile Toe Slippage Due to Steep Incline BedrockSolution #1Use Oslo Point Shoe To Minimize Pile Damage
  154. 154. Pile Breakage on Inclined Rock Surface No Proper Pile Shoe
  155. 155. Extension Pile PileJoint
  156. 156. First ContactB/W Toe andInclined Rock
  157. 157. Pile Joint Breaks Pile Body Bends Toe “Kicked Off” on Driving
  158. 158. Pile Breakage on Inclined Rock Surface Continue “Sliding” of Toe
  159. 159. Use Oslo Point Shoe to Minimize Damage
  160. 160. Design and Construction Issues #2Issue #2Presence of CavitySolution #2Detect Cavities through Cavity Probing thenperform Compaction Grouting
  161. 161. Presence of Cavity Pile Sitting on Limestone with Cavity
  162. 162. Application ofBuilding Load
  163. 163. Application ofBuilding Load Roof of Cavity starts to Crack …
  164. 164. Building CollapsePile Plunges ! Collapse of Cavity Roof
  165. 165. Design and Construction Issues #3Issue #3Differential SettlementSolution #3Carry out analyses to check the settlementcompatibility if different piling system is adopted
  166. 166. Differential Settlement of Foundation Link House of SAFETYOriginal BuildingConstruction Cracks!!Not Compromised Original House Renovation: on Piles Construct Extensions Piling in Progress No Settlement Settlement Soft Piles No transfer pile Layer Load to Hard Layer Hard Layer SPT>50
  167. 167. Eliminate Differential Settlement Construct Extension with Suitable Piles Piling in Progress SoftLayer Hard Layer All Load transferred to Hard Layer – No Cracks! SPT>50
  168. 168. Problem of Short Piles Cracks!! Construct Extensions with Short Piling in Progress Piles Load transferred to Soft Soft! Soft Layer,Layer Extension still Settles Hard Layer Load from Original House transferred to Hard Layer SPT>50
  169. 169. Cracks at Extension
  170. 170. Typical Design and Construction Issues #4Issue #4Costly conventional piling design – piled to set todeep layer in soft groundSolution #4-Strip footings / Raft-Floating Piles
  171. 171. “Conventional” Foundation for Low Rise Buildings
  172. 172. Foundation forLow Rise Buildings (Soil Settlement)
  173. 173. Settling Platform Detached from Building Settlement Exposed Pile
  174. 174. Conceptual Design of FOUNDATION SYSTEM1. Low Rise Buildings :- (Double-Storey Houses) = Strip Footings or Raft or Combination.2. Medium Rise Buildings :- = Floating Piles System.
  175. 175. Low Rise Buildings on Piled Raft/Strips Fill Strip / Raft System25-30mSoft Clay StiffStratum Hard Layer
  176. 176. ComparisonBuilding on Piles Building on Piled Strips Fill 25-30m Soft Clay Strip System Stiff Stratum Hard Layer
  177. 177. Comparison (after settlement)Building on Piles Building on Piled Strips Fill 25-30m Soft Clay Strip System Stiff Stratum Hard Layer
  178. 178. Advantages of Floating Piles System1. Cost Effective.2. No Downdrag problems on the Piles.3. Insignificant Differential Settlement between Buildings and Platform.
  179. 179. Bandar Botanic
  180. 180. Bandar Botanic at Night
  181. 181. Soft Ground Engineering
  182. 182. Myths in Piling
  183. 183. MYTHS IN PILING #1Myth: Dynamic Formulae such as Hiley’s Formula Tells us the Capacity of the PileTruth:Pile Capacity can only be verified by using: (i) Maintained (Static) Load Tests (ii)Pile Dynamic Analyser (PDA) Tests
  184. 184. MYTHS IN PILING #2Myth: Pile Achieves Capacity When It is Set.Truth: Pile May Only “Set” on Intermediate Hard Layer BUT May Still Not Achieve Required Capacity within Allowable Settlement.
  185. 185. CASE HISTORIESCase 1: Structural distortion & distressesCase 2: Distresses at houses
  186. 186. CASE HISTORY 1Distortion & Distresses on 40Single/ 70 Double Storey HousesMax. 20m Bouldery Fill onUndulating TerrainPlatform SettlementShort Piling ProblemsDowndrag on Piles
  187. 187. Distresses on Structures
  188. 188. Void
  189. 189. 70 Piling Contractor A Offset 36.2m Offset 13.1m Building Offset 13.1m Platform 60 Offset 13.1m OriginalR e d u c e d L e v e l (m ) Ground Profile 50 N=34 ? ? N=30 40 ? ? N=5 N=40 ? ? ? ? Filled ground N=25 ? Original Ground ? ? 30 N=29 ? Hard Stratum Borehole Pile Toe Profile with SPT N≅30 Pile Toe of Additional Profile with SPT N>50 Piles 20 0 40000 80000 120000 160000 200000 Coordinate-X (mm)
  190. 190. 80 Piling Contractor A Piling Contractor B 70 Offset 9.1m Offset 9.1mR e d u c e d L e v e l (m ) 60 N=34 Profile with SPT N≅30 Building Platform N=28 50 ? N=41 ? N=30 Original Ground Profile Filled ground Original Ground ? ? 40 N=5 Hard Stratum Borehole N=29 Pile Toe Pile Toe of Additional ? Piles Profile with SPT N>50 30 0 40000 80000 120000 160000 200000 Coordinate-X (mm)
  191. 191. Prevention MeasuresDesign:– Consider downdrag in foundation design– Alternative strip systemConstruction:– Proper QA/QC– Supervision
  192. 192. CASE HISTORY 2Distresses on 12 Double StoreyHouses & 42 TownhousesFilled ground: platform settlementDesign problem: non-suspended floorwith semi-suspended detailingBad earthwork & layout designShort piling problem
  193. 193. Diagonal cracks due to differentialsettlement between columns Larger column settlement
  194. 194. Sagging GroundFloor Slab
  195. 195. SAGGING PROFILE OF NON- NON-SUSPENDED GROUND FLOORSUSPENDED GROUND FLOOR SLAB SLAB BEFORE SETTLEMENT V ρs V <V e > Vc V c c e PILE PILECAP BUILDING PLATFORM PROFILE AFTER SETTLEMENT ρs ACTUAL FILLED PLATFORM SETTLEMENT
  196. 196. Distorted Car Porch Roof
  197. 197. Poor Earthwork LayoutSilt trap BLOCK 2 Temporary earth drain BLOCK 1
  198. 198. Prevention MeasuresPlanning:– Proper building layout planning to suit terrain (eg. uniform fill thickness)– Sufficient SIDesign:– Consider filled platform settlement– Earthwork layoutConstruction:– Supervision on earthwork & piling
  199. 199. SUMMARYImportance of Preliminary StudyUnderstanding the Site GeologyCarry out Proper Subsurface Investigationthat Suits the Terrain & SubsoilSelection of Suitable PilePile Design Concepts
  200. 200. SUMMARYImportance of Piling SupervisionTypical Piling Problems EncounteredPresent Some Case Histories
  201. 201. 54 PEOPLE TOOK PART IN THIS CONCERTED ACROBATIC JUMP.FERRARI ‘S PITSTOP WAS COMPLETED BY15 MECHANICS (FUEL AND TYRES) IN 6.0SECONDS FLAT.

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