Republic of Indonesia

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MoU on Soft Soil Engineering 1996-2001
Regional Teaching Program 2001 Soil investigation
and parameter determination

• Republic of Indonesia
• Kingdom of the Netherlands
• RT-05 July 9th - 2001

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Contents (1)

• Purpose
• General aspects
• Boundary conditions
• Scope of work
• Design stages
• Preliminary investigation
• Investigation approach final design
• Site investigation techniques
• Laboratory testing
• Parameter determination

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Contents (2)

• Cost estimate
• Correlations
• Presentation of results

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Main Purpose of soil investigation

• Obtain an adequate (better) insight in the
  behaviour of the subsoil and fill material, so
  that it is possible to optimise the design of the
  construction, regarding risk assessment
• Important parameters of subsoil and fill are
• stiffness Cc, C, cv
• strength Phi, (un) drained cohesion

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Sub purposes of soil investigation

• Geotechnical soil profile
• Representative cross sections
• Soil stratification
• Geotechnical parameters
• Geo-hydrological parameters
• Groundwater table and piezometric heads
• Environmental investigations and data

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Wrong soil investigation approach
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Wrong soil investigation approach
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General aspects

• Depending on the kind of project site visit
• Determine geotechnical category (GC) of
  structure
• depends on risk assessment
• determines the amount and accuracy of the soil
  investigation
• Peat layers ask for special attention
• Determine the failure mechanisms
• shearing, squeezing, settlement, horizontal
  deformation, negative skin friction

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Boundary conditions and requirements

• Primary boundary conditions
• stability and (residual) settlements
• availability of local construction materials
• functional requirements (dimensions)
• time frame
• site condition subsoil and water levels
• loads
• special attention to cables, pipes, other
  constructions
• maintenance cost optimisation

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Scope of work

• Based on program of requirements PoR
• The amount of soil investigation depends on
  design stage the project is in
• Is it wise to carry out soil investigation in
  stages?
• Design requirements
• road classification (related to GC)
• dimensions of the embankment
• design levels
• loads in construction and operational phase

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Scope of work

• dead weight, earthquake variable load (traffic,
  groundwater change)

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Design stages

• Tune soil investigation to the design stage

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Soil investigation vs model parameters

• Prediction models

• Soil investigation

• Interpretation?

• Soil Parameters

• Interpretation

• Model parameters

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Preliminary investigation

• The use of archive
• Site visit

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Preliminary investigationThe use of archive

• Site situation
• Soil structure
• Use of archive material and maps
• Geo-hydrological conditions
• Info cables, pipelines etc
• Experience from recently carried out comparable
  projects

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Preliminary Investigation Site visit

• Site conditions (actual)
• Geologic and geotechnical conditions
• Geo-hydrological condition (open water)
• Historical information (old rivers, drains)
• Estimate the scope of field investigation
• is the site accessible for equipment?
• steep slopes?
• First briefing on geotechnical conditions for
  planning and design process

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Investigation approach soil investigation

• Approach to soil investigation
• starting points sequences
• Investigation techniques
• Intensity
• amount of borings, in situ testing
• amount of (un)disturbed samples

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Starting points and sequence
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Soil investigation progress
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Site investigation techniques
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Site investigation techniquesExample CPT

• Cone resistance
• Sleeve friction
• Friction ratio

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Site investigation techniquesWater-level
measurements

• Important, however expensive
• measuring groundwater level
• measuring piezometric level
• measuring during construction stages

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Site investigation techniques Intensity

• Variation in soil stratification
• Accuracy (stability settlements)
• Safety
• Amount of soil investigation
• CPT /boring field tests each 100 -250 m
• samplings each 1-2 m depth
• Atterberg limits, field vane is powerful
• Higher intensity
• less supervision and monitoring
• in case of a problem easier to tackle
• design values more close to mean values
• risk of calamities decreases

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Laboratory testing

• Purpose
• if possible do direct testing
• Type
• Classification tests
• Quantitative tests
• Parameter determination (site lab)

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Laboratory testingClassification

• Water content
• Organic content
• Degree of Humification
• Fiber content
• Bulk density
• Atterberg limits
• Visual identification by an expert

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Laboratory testingQuantitative tests in situ

• Parameter determination derived from in situ
  testing

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Laboratory testingQuantitative tests in lab

• Parameter determination derived from laboratory
  testing more direct measurement

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Parameter determination
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Cost estimate

• Remark do it before starting!!
• Costs
• Mobilisation demobilisation
• Personal (supervisor crews)
• Field tests (boring, samplings, etc)
• Laboratory testing
• Reporting
• Interpretation and analysis

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Correlation's

• Very powerful for design
• Cheap
• More than a rule of thump
• Gain in future own correlation's for Indonesian
  Peat
• Correlation's empirical and regression equations
  (compare with tables for clay deposits in
  literature J.E. Bowles)

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Examples of correlation's

• Settlement
• look for regression equations with respect to to
  peat
• Compression index versus water content w, or
  Liquid Limit LL
• Terzaghi and Peck
• Nishida
• Compression ratio CR versus void ratio e
• Coefficient of consolidation cv versus Liquid
  Limit
• Coefficient of secondary compression Calfa vs
  water content w

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Correlation CPT vs. soil type
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Presentation of the results

• Give the client the feeling he paid for something
  worthwhile
• Geotechnical report
• present clear figures
• present interpretation/analysis of factual data
• present geotechnical parameter set for the
  predictions in a table
• present factual data separately
• Store the factual data for future projects

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Presentation and store(example of a computer
program)
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Presentation and store(example of a computer
program)
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Example presentationParameters in a graph
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Example presentation3D block model
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Example presentationGeotechnical Profile
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Example presentation3D solid layers
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Example presentationThickness or depth map
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Figures tend to give more insight than tables
Station Vijzelgracht
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Application Export of geometry to software
Plaxis, Finite Element Methods
MGeo serie, analytical calculation software
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Recommendations

• Do not forget soil investigation on fill material
• Think about the purpose of soil investigations
  prior to the start of a project
• Soil investigation and analysis is an essential
  part of the design
• Clear presentation of the interpretation of
  factual data is important
• Carry out soil investigations in different
  phases, related to the design stages

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Excercise

• An embankment with a height of 6 metres above
  surface level needs to be constructed
• The subsoil can be described as follows
• up to 3 metres below surface peat
• beneath this layer a 3 metres thick silty clay
  layer is encountered
• beneath the silty clay layer sand is encountered
• The groundwater level reaches up to the surface

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Excercise

• Preleminary study
• Determine the required data (make a list)
• Determine the possible geotechnical problems
  (make a list)

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Excercise

• Soil investigation and parameters
• Perform a soil investigation program
• Make a cost estimate
• Determine the parameters required for stability
  and settlement calculations
• How can the parameters can be determined?
• Perform a laboratory test program