Republic of Indonesia

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MoU on Soft Soil Engineering 1996-2001
Regional Teaching Program 2001 Design options and
fill materials

• Republic of Indonesia
• Kingdom of the Netherlands
• RT-09 July 9th - 2001

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Contents

• Design Philosophy
• General construction techniques
• Fill excavation techniques
• Use of lightweight materials
• Techniques for accelerating consolidation
• Techniques for reinforcing embankment
• Techniques for reducing deformation
• Comparison of the methods
• Alternative construction techniques

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Design philosophy

• For every project the following needs to be
  considered
• Choice of construction method and fill material
  based on
• costs
• available time
• local experiences
• local contactors, equipment

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Design philosophy

• available building area
• physical boundaries (gullies, buildings etc.)
• availability of (fill) materials
• Try to choose the technical/economical optimum
  solution
• Convince the client of the best option you think
  that has to be applied
• Share your considerations with the client

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General construction techniquesFill
excavation techniques

• Staged construction
• Pre-loading
• Replacement method
• Displacement method

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General construction techniquesFill and
excavation techniquesStaged construction

• Why?---------gt dealing with stability problems

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General construction techniquesFill
excavation techniquesStaged construction

• Purpose is to prevent stability problems due to
  high excess pore pressure
• Problems arise mainly at edges
• Each step induces less load, due to smaller
  volume and more spreading
• Reduction in excess pore pressures needs to be
  large enough in order to apply subsequent fill
  layer
• Dry or wet (hydraulic) filling, depends on the
  size of the project

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General construction techniquesFill and
excavation techniquesStaged construction

• Each step induces smaller load as a smaller
  volume and as more spreading

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General construction techniquesFill and
excavation techniquesPre-loading

• Why? -------gtreduce residual settlement
• Time vs. settlement

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General construction techniquesFill
excavation techniques Displacement techniques

• Not recommended
• Sand seeks the route of the least resistance
• Little control on end result
• Sand tends to be packed loose
• Heave may occur
• Not applicable near cables, pipelines or other
  constructions

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General construction techniquesFill
excavation techniques Replacement techniques

• Fill is placed in cunets
• Reduction of (residual) settlements
• May be locally used at the toe
• Be aware of seepage in polders
• Preferably apply on uniform soft soil layer
  (otherwise differential settlements)
• Reuse excavated soil as cover

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Use of lightweight materials

• Only in special occasions
• Criteria
• available time between fill and completion
• demand on little residual settlements
• effect on vicinity
• availability and costs of alternatives
• Extra measures for pavement construction and
  wrapping of material in mattress

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Use of lightweight materials

• Example of materials
• Natural materials of vegetable origin
• EPS foam
• Foam concrete
• Expanded clay pellets
• Aerated slags
• others ?

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Techniques for accelerating consolidationremark
only effect the the primary settlement

• Horizontal drainage (depth till 7 m)
• Vertical drainage
• Sand drain method
• Composite drains (paper and synthetic drains)
• Sand compaction method
• Sand compaction pile method
• Vacuum consolidation

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Techniques for accelerating consolidationVertica
l drainage (design)
Principle is shortening the drainage length,
hence the consolidation time is shortened
dramatically

• Without drain

• Fill

• Soft soill

• With drain

• Fill

• Soft soill

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Techniques or accelerating consolidationVacuum
consolidation

• Often in combination with vertical drains and
  filling
• The subsoil is not subjected to shearing
• Fill can proceed quicker and with steeper slopes
• Often false air suction in the edges results in
  loss of under pressure

• Often applied near bridge embankments
• experience in east Asia

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Vacuum consolidation
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Techniques for reinforcing embankment

• Function prevent loss of stability or
  unacceptable deformation
• Examples
• Geo-synthetic mattresses
• 4 functions reinforcement, separation
  (undesired mixture), filter drainage
• Corduray Galar Kayu or Knople
• Tree Branches

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Techniques for reducing deformation

• Columns formed in the ground
• Timber piles
• Pile slab method

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Techniques for reducing deformation

• Columns formed in the ground
• sand columns
• stone column
• vibro concrete columns
• lime column
• yet grouting
• others

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Techniques for reducing deformation

• Timber piles
• often used in Indonesia
• piles in firm layer, be aware of pavement
  settlement between piles
• piles not in firm layer
• pile group acts as friction piles friction not
  sufficient to resist the total load settlement

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Techniques for reducing deformation
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Pile slab
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Comparison of construction methods

• No general solution
• Solution depends on situation
• Methods for making a choice
• Multi-criteria analyses
• Costs-derived assessment
• For both methods experience is necessary what
  is feasible with respect to main starting
  points
• settlement, stability, time frame
• Costs investment and maintenance costs

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Multi Criteria Analysis

• Determine main criteria
• Determine sub-criteria
• Weighting factors
• Determine (on own experience) the feasible
  alternatives
• Comparison of alternatives
• use quantitative values or
• qualitative comparison (--,-,0,,)

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Costs -derived assessmentCosts of alternatives

• Preparation costs
• Construction costs
• Supervision costs
• Maintenance costs
• Demolition costs
• Interest

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Recommendation

• Use the method construct by the observation
  method
• Monitoring
• Learn form other equal projects in the vicinity

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Alternative construction techniques

• Traditional methods
• cerucuk piles, corduray, wood waste
• Common methods
• replacement/displacement, pre-loading, vertical
  drainage
• Special methods (only for specific situations)
• vacuum consolidation in combination with fill and
  vertical drainage

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Alternative construction methods

• Question to the audience
• What type of alternative construction methods do
  you know and can you explain your experiences
  with these methods?

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Exercise

• Prepare a recommendation of the most favourable
  construction method for the eastern embankment of
  the bridge as mentioned in the general excercise
  RT-A. The design level of the embankment is 6 m
  above de existing surface
• Use a simplified MCA
• Prepare a presentation of your study for the
  local government