Pertemuan 05 PEMILIHAN MATERIAL GEOTEKSTIL, GEOGRIDS/GEONETS

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Matakuliah S0522/ Aplikasi Geosintetik Dalam
Teknik Sipil Tahun Juli 2005 Versi 01/01

• Pertemuan 05PEMILIHAN MATERIAL GEOTEKSTIL,
  GEOGRIDS/GEONETS

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Learning Outcomes

• Pada akhir pertemuan ini, diharapkan
• mahasiswa akan mampu
• Mahasiswa mampu mengkategorikan pemakaian
  geonets, geogrid dan geotekstil sesuai kebutuhan
  desain di lapangan ? C5

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Outline Materi

• Pertimbangan desain
• Kondisi tanah
• Analisa pemilihan material
• Perbandingan penggunaan geotekstil dan geogrid ,
  serta geonets sesuai kebutuhan dan kondisi
  lapangan

Sebagian materi ini diambil dari IGS Lecturer
notes No. 9 of 19 Reinforced Soil - Steep Faced
Embankments By Jerry Love Geotechnical Consulting
Group, UK
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• Lecture Outline
• Application areas and general introduction
• Types of geosynthetics and fill material used
• Review of design methods
• Examples of installation of geosynthetics
• Examples of completed structures

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Application Areas
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Highway Widening
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Temporary Structures
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Slip Repairs
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Noise Barriers
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Use of Poor Quality Fills
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Summary

• Reinforcement allows soil structures to be built
  at angles steeper than the natural angle of
  repose of the soil
• Advantages include
• Simple construction methods
• Manual handling
• Lightweight plant
• Cheaper fill material
• More rapid construction
• Tolerance to differential movement
• Visually pleasing structures

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Types of Geosynthetic Used
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Geogrid/soil Interlock
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Woven Geotextiles
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Non Woven Geotextiles
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Fill Materials

• Granular fill
• Cohesive fill
• Chalk fill
• PFA

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Design Methods
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• Step 1
• Establish the geometric, loading, and performance
  requirements for design
• Geometry
• Loads
• Performance requirements

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• Step 2
• Determine the stratigraphy and engineering
  properties of the insitu soils in and below the
  slope
• Soil profiles
• Soil strength parameters, unit weight, and
  consolidation parameters
• Groundwater regime
• Cause of previous instability if applicable

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• Step 3
• Determine the engineering properties of the fill
  material
• Gradings and plasticity
• Compaction characteristics and placement
  requirements
• Shear strength parameters
• Chemical composition of soil

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• Step 4
• Determine design parameters for the
  reinforcement.
• Long-term rupture strength
• Pull-out strength
• Direct sliding coefficient

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• Step 5
• Determine the factor of safety of the
  un-reinforced slope
• Standard stability analysis computer programs
• Is reinforcement required?
• Establish the size of the critical zone to be
  reinforced

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• Step 6
• Establish reinforcement layout
• Method 1 Direct method using
  prescriptive design rules or charts
• Method 2 Iterative method using
• trial-and-error technique

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Two Part Wedge Method (UK Highways)
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Trial Surfaces
T (available) t1t2t3t4
T (available) gt t (required)
t1
t2
t3
t4
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Typical Reinforcement Layout

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Check External Stability

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• Step 8
• Evaluate requirements for subsurface and surface
  water control
• drains placed at the rear and/or beneath the
  reinforced zone.
• Surface water collector drains above the
  reinforced slope.
• Front face erosion protection
• This completes the design process.

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Typical Installation by Pushing Fill Forward
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Placing Fill by Excavator Bucket
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Steep Faced Slope With Mesh Facing
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Steep Faced Slope, Soft Face With Berms
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Green Faced Steep Slope
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Bridge Abutment
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Geotextile Wrap Round Face
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Green Faced Steep Slope