Matakuliah: S0522/ Aplikasi Geosintetik Dalam Teknik Sipil Tahun: Juli 2005 Versi: 01/01 Pertemuan 05 PEMILIHAN MATERIAL GEOTEKSTIL, GEOGRIDS/GEONETS

Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu :  Mahasiswa mampu mengkategorikan pemakaian geonets, geogrid dan geotekstil sesuai kebutuhan desain di lapangan  C5

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

Lecture Outline 1Application areas and general introduction 2Types of geosynthetics and fill material used 3Review of design methods 4Examples of installation of geosynthetics 5Examples of completed structures

Application Areas

Highway Widening

Temporary Structures

Slip Repairs

Noise Barriers

Use of Poor Quality Fills

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

Types of Geosynthetic Used

Geogrid/soil Interlock

Woven Geotextiles

Non Woven Geotextiles

Fill Materials Granular fill Cohesive fill Chalk fill PFA

Design Methods

Step 1 Establish the geometric, loading, and performance requirements for design: Geometry Loads Performance requirements

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

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

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

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

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

Two Part Wedge Method (UK Highways)

t1 t2 t3 t4 T (available) = t1+t2+t3+t4 T (available) > t (required) Trial Surfaces

Typical Reinforcement Layout  Primary reinforcement Secondary reinforcement Main reinforcement wrapped round face

Check External Stability

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.

Typical Installation – by Pushing Fill Forward

Placing Fill by Excavator Bucket

Steep Faced Slope With Mesh Facing

Steep Faced Slope, Soft Face With Berms

Green Faced Steep Slope

Bridge Abutment

Geotextile Wrap Round Face

Green Faced Steep Slope