PROBLEMS SOLUTIONS OF PEAT SOILS IN ENGINEERING …

1 PROBLEMS & SOLUTIONS OF PEAT SOILS IN ENGINEERING APPLICATIONSby Ir. Liew Shaw ShongIntroductionProblem StatementsSolutions for ApplicationSummary & ConclusionsCharacteristics of Peat SOILS Lighter than water Always on top of formation & within depressions High mobility with flow Compressible & creeping High volumetric changes Weak strength Low resistance against destabilising actions High void ratio & permeable Good water storage & high seepage flow rate Decomposable Low pH (acidic) Fire hazard & combustible gasesCharacteristics of PeatsCharacteristics of PeatsCase Study 1 Open pit coal mine operation PROBLEMS .

2 High groundwater, excavation induced seepage flow, weak strength, high mobility flow failure SOLUTIONS : Dewatering & rechargingGround ConditionsMudstonePeaty SoilsOriginal GWTD rawdown GWTF ailure MechanismMudstonePeaty SoilsOriginal GWTD rawdown GWTO ption A Dewatering SchemeMudstonePeaty SoilsSteady State Drawdown ProfileOriginal GWTBundRecharge PondExtraction WellOption B Gravity Mass with Groundwater BarrierMudstonePeaty SoilsEarth CoreOriginal GWTBundOption C Structural Groundwater Cut Off WallMudstonePeaty SoilsOriginal GWTBundDiaphragm Wall/ Sheet PilesOption D Ground ImprovementMudstonePeaty SoilsOriginal GWTBundJet Grouting/ Stone Columns/Soil Mixing PilesTechnical

3 Comparison & Scheme Economical Uninterrupted SCADA Monitoring (Lowest) Simple & Easy for Implementation Design Redundancy & Contigency Plan Reusable of Equipment at other areas Large Setback Area Environmental Friendly Backup Supply is also Mass with Groundwater Barrier More Robust Design Costly and Time One Off Treatment Required Longer Haulage Consume part of the Mining Waste. High Risk of Trench Excavation Requiring Access of Heavy Groundwater Cut Off (Wall Diaphragm Wall) More Robust Design Costly & Difficulty in Tremie Concrete One Off Treatment Risk of Unstable Wall Trenching Simple & Easy for Implementation Acidic Condition Requiring Access of Heavy Machineries Less Environmental FriendlyStructural Groundwater Cut Off Wall (Sheet Piled Wall)

4 More Robust Design Costly Installation of Sheet Pile Walling No Serious Maintenance is needed Requiring Access of Heavy Machineries Sheet Piles are Recycleable Simple & Easy for Improvement More Robust Design Costly One Off Treatment Less Environmental Friendly Simple & Easy for Implementation Requiring Access of Heavy MachineriesCase Study 2 Palm oil mill project PROBLEMS : Weak soil strength to support structural loading, excavation instability, consolidation & creep settlement, high permeability SOLUTIONS : Pile foundation, structural retaining system, piled raft system, ground reinforcing system.

5 Pond lining systemSite LocationProject Requirements Reduce Platform Thickness Reduce Construction Time & Cost Use Local Materials & Reduce Transported Construction Materials from Outside Innovative Geotechnical Design for Very Difficult Ground ConditionsSubsoil ConditionsCrusher runOGLH eavy MachinerySteel Sand FillLightMachinerySteelColumnPile cap36m Prestressed Concrete Circular Spun Piles46mVery Soft to Medium Stiff Compressible Marine Clay 9m Hardwood Blanket Piles9m Hardwood PilesNon Suspended SlabDense SandHardwood Blanket PilingReinforced Soil PlatformWoven GeotextileLean Concrete over Hardwood PilesColumn StumpCrusher Run to be filled to highFrictional Pile Foundation for StructureTemporary Pilecap ExcavationTipping Pit ExcavationTank Foundation2500-Ton Oil Storage Steel Sand FillDense Sand46mVery Soft to Medium Stiff Compressible Marine Clay R.

6 C. Tank RaftPrestressed Concrete Circular Spun PilesWithVarying Lengths(24m, 30m and 36m)Tank FoundationCompleted Tank FoundationRetaining System for Crane Bay(Gravity Containment System)Perspective View FFB Crane Bay46mVery Soft to Medium Stiff Compressible Marine Clay Dense Canal Water12m LongFSP III Steel Sheet PilesReinforced ConcreteWharf DeckFFB Crane BayCanal to be excavatedFSPIIIA Sheet Pile WallFFB Crane BayCompleted FFB Crane Bay & CanalEffluent PondCompleted Palm Oil MillSummary & ConclusionsUnderstand the behaviours of ground materialsIdentify problem statementsDevise options for solutionTHANK YOU