Geotextile Engineering : Application in Civil and Environmental Engineering
Shobha K. Bhatia Syracuse University, New York
ASCE Expo 2012 Outline
Introduction History Classification Properties Applications Innovations Conclusions Geotextiles
Permeable textile used in conjunction with soil or rock.
Integral part of many manmade structures, such as levees, dams, roads, retaining walls, steep slopes, landfills and others. ZIGGURAT – woven mat reinforcement
Ziggurat of Ur in Mesopotamia ~ 2500 B.C. History Initially referred as “civil engineering fabrics” or “filter fabrics.” First use in 1926: Cotton fabric with hot asphalt (geomembrane kind of material) was field tested. Polymer based woven industrial fabrics (geotextile) were used beneath concrete block revetments in late 1950s. Early 1960s, geotextiles were typically woven polyproplene monofilament fibers. Major Breakthroughs
In 1956, Dutch engineers used geotextiles to overcome dilemmas present in their Delta Works Scheme Hand woven from 100-mm wide 1-mm thick nylon strips From 1960s, polymeric woven geotextiles were commonly considered in coastal protection works. Major breakthroughs Mid 1960s, geotextile filters were considered only on sites where granular filters were not readily available. In 1968, FHWA monitored pavement overlay repair schemes where geotextiles were installed to control reflective cracking in asphalt surfacing. First nonwoven needle punched polyster geotextile was developed by Rhone- Poulenc company in France. Major breakthroughs
Valcros Dam In 1970, thick nonwoven geotextiles were used as filters beneath rip rap protection. 55Ft High Dam, Slity Sand ,30%<0.075mm. Polyester Continuous filament needle punched nonwoven geotextile, 300g/m2. Continuous trickle of clean water for 35 years.
At the same time, ICI started producing thinner heat bonded nonwoven geotextiles Major Breakthroughs In 1973, three basic functions of geotextiles were identified Separation Filtration Reinforcement In 1974, drainage was added as fourth basic property. By early 1990s, cushioning or protection was added as the fifth basic property.
VALCROS DAM, 55 ft (1970)
First Dam with Geotextile Filter Manufacturer’s and sales
In 1957, after a tropical storm caused severe beach erosion at the home of the president of Carthage mills, he started working with engineers from Coastal Engineering Laboratories of University of Florida to use Carthage Mills fabrics to protect his property against future storms.
This resulted in first use of woven filter fabric in waterfront structures. Manufacturer’s and sales
Research sponsored by AB Fodervavnader of Bora, Sweden, a small specialty weaving company resulted in the world’s first pullout test device. Geotextiles The manufacturing of synthetic fibers Transforming raw polymer from solid to liquid form. Extruding fibers through spinneret, and Solidifying the fibers into continuous filaments. Various textile-forming technologies used to make: Woven ,Non-woven, Knitted and Stitch- bonded Geotextile Classification Types Warp Woven- weave pattern and fiber Threads Plain Weave, Basket Weave, Twill Weave, satin weave
Weft Non-woven -Spun Bonding Thread
Weaving Polymer Chip Direction
Fiber Bonding
Winding Knitted –seldom used Fibers
Geotextiles are made of synthetic fiber Polypropylene (92%) Polyster (5%) Polyethylene (2%) Nylon (1%)
Slit Film Tapes Yarns
Different types of yarn Monofilament fibers Heterofilament fibers Multifilament yarns Multi Filament Yarns Staple fibers Slit-film tapes Fibrillated yarns
Different Type of Geotextiles Natural Fibers
Fiber types: natural (wood, straw, coconut, jute), synthetic (PP, PET, nylon), and combinations (straw/coconut, wood/synthetic)
Fiber structure types: short, long, multifilament
RECP structure types: ECNs, OWTs, ECBs, and TRMs
92 different degradable RECPs and 37 different non-degradable RECPs are available in the US
RECPs –
wood excelsior wood/synthetic blend straw/coir
Coir Coir Jute Types and Properties
20 different companies market geotextiles 87 Woven and 124 nonwoven geotextiles Properties- Transportation Related Application Mass per unit area, percentage open area, Permittivity, puncture resistance, tear and grab strength, survivability Reinforcement Application Wide width tensile strength, creep limited strength
Geotextile consumption
Year 1970 1980 1990 1998
Millions of 5 100 300 600 square meters ,North America
Million of 10 60 250 App.400 square meters, Western Europe Million square 100 meters , Japan (all geosynthetics)
Growing market in China and India………… Relative importance of geotextile functions in geotechnical applications
Application Separation Filtration Reinforcement Drainage Protection
Temporary and permanent 1 2 2 pavements
Asphalt overlays 1 2 2 Railways 1 3 3
Embankment 3 3 1 3
Retaining walls and slopes 3 3 1 3 Erosion control 3 2 3 3 2
Subsurface drainage 3 1 Membrane protection 3 1
(1) Primary Function (2) Secondary Function (3) Tertiary Function Geotextile Properties Geometric Information
Schematic
25 cm²
2 kPa
thickness
metal base
Measuring thickness at 2 kPa
The test is performed to EN964 part 1 for a single layer products and to EN964 part 2 for multi-layer
Sampling Measuring (mua) Mechanical Properties
Short-term tensile strength and dependent deformation Long-term tensile behaviour (creep/creep rupture) Long-term compressive creep behaviour (with/without Shear stress) Resistance against impact or punching Static puncture test, rapid puncture Resistance against abrasion Friction properties Direct shear, inclined plane test, pullout resistance Protection efficiency Damage during installation Geosynthetics or composites internal strength Geosynthetic reinforcement segmental retaining wall unit connection testing Mechanical Properties
Testing machine with Capstain clamp for geogrid video-extensometer with laser-extensometer Tensile Tests
ε Force - Strain behaviour of Geosynthetics
Fm 1 kN/m 2 3 100 Woven Fabrics, 90 4 80 GeoGrids 70 60 5 50 PP - M 40 PP/ PE - T 30 20 PP/ PET - T HD PE - M 10
strain 10 20 30 40 50 60 70 80 90 100 % Tensile Creep and Creep Rupture EN ISO 13431 : 1996 ASTM)
Tensile creep tests give information on time-dependent deformation at constant load. Creep rupture tests give time until failure at constant load. A deformation measurement is not necessary for creep rupture curves. Loads for creep testing are most often dead weights, often enlarged by lever arms. Multiple Creep Rupture Rigs in a Temperature Controlled Chamber Resistance To Static Puncture
Static Puncture Test: The Test CBR (EN ISO 12236 : 1996)
The use of soil mechanics California Bearing Ratio (CBR) apparatus for this static puncture test, has resulted in the unusual name for this test.
A plunger of 50mm diameter is pushed at a speed of 50 +/- 10mm min onto and through the specimen clamped in the circular jaws. Measurement of force and displacement are taken. The test is widely used for geotextiles, it is not applicable to grids, and the test provides useful data for geomembranes.
CBR - device Inserting in testing specimen in machine hydraulic CBR- clamps Impact Resistance Test (CEN TC 189 WI 14; ISO 13428 draft)
Efficiency of protection materials can be tested by dropping a hemispherical shaped weight onto a specimen placed on a lead plate on a resilient base.
The impression in the lead and the condition of the specimen are recorded.
Lighter round shaped drop weights are used for other geosynthetics. The deformation of a metal sheet under the tested material gives quantitative results. Impact Resistance Test
Drop weight, lead platen, specimen under ring Impact Resistance Test (performance test : BAW)
A heavy drop weight (67.5 kg) is dropped from 2 m height on the geosynthetic placed on sand and fixed in a ring. The result is a “penetration yes or no” decision.
67.5 kg
2 m
Result of drop tests - The Test no penetration Abrasion Resistance (EN ISO 13427 : 1995)
Emery cloth of a specific grade is moved linearly along the specimen. After 750 cycles the abraded specimen is tested to measure the residual tensile strength or hydraulic properties
Example of Apparatus with Sliding Block Specimen Specimen after before test abrasion test Direct Shear Friction (EN ISO 12957 : 1998)
Reinforcing geosynthetics develop their tensile resistance by the transfer of stresses from the soil to the fabric through friction. The friction ratio is defined as the angle of friction, the ratio of the normal stress to the shear stress. Low normal stresses may be tested by an inclined plane test and higher normal stresses by direct shear or by pull out test.
Direct shear (EN ISO 12957-1) The friction partners are placed one in an upper box, the other in the lower box. The lower box is moved at a concentrate of displacement (index testing: 1 mm/min) while recording force and displacement. The results for three normal stresses (50, 100, 150 kPa) are plotted, the value of friction angle is calculated Section Through Shear box Test
Damage During Installation
The CEN-ISO standard applies a cyclic load to a platen (100 x 200) pressing via a layer of Corundum aggregate placed on top of the geosynthetic being tested. (Corundum is a trade name for a sintered aluminium oxide.
After 200 cycles between 5 kPa and 900 kPa maximum stress the specimen is exhumed and may be subject to a tensile test for the residual strength for reinforcement applications, or for filtration the hydraulic properties for filtration applications.
A performance test requires the soil and fill to be used on the site and the equipment to spread and compact the material.
Typical results of an index-test are shown Material Before (left) and After (right) Damage Test
Characteristic Opening Size (EN ISO 12956 : 1999)
To determine, which grain size can passing through a geosynthetic and which is retained, a wet sieving test is used with a standard “soil”. The ‘soil’ passing the geotextile is extracted from the water and sieved again.
A characteristic value O90- is calculated according to EN ISO 12956.
O90 = d90 of the ‘soil’ passing the geosynthetic
Dry Sieving
Hoop sizing Sagging Broken and irregular glass beads Trapping within the geotextile Electrostatic effects Time for the Test Wet Sieving
Hoop sizing sagging Great chance for error: a. Leakage between sieves b. Analyzing passed glass beads (<325 mesh) Glass bead clumping on geotextile Elimination of electrostatic effects Time for the test Pores with Glass Beads
Plan view Side view 100 Product: Texel, 909 90 PET/PP, Staple, Needle- 80 punched, Nonw oven Thickness: 2.3 mm 70 W2 - Permeability: 0.45 cm/sec 60 AOS: 0.07-0.11 mm (Dry multifilament 50 Sieving) Bubble Point: 0.116-0.135 Mineral Oil 40 mm Silw ick 30 O95: 0.098-0.11 mm Percent Finer (%) Finer Percent O50: 0.069-0.076 mm Porew ick 20 10 0 1 0.1 0.01 Diameter ( mm) Pore size, volume, permeability, density, surface area, and adsorption
Comparison of Wet Sieving & Bubble Point Method
Bubble Point Method: 0.12 mm 100 90 80 70 Amoco 4510 Sample A 60 Amoco 4510 Sample B 50 Amoco 4510 Sample C Amoco 4510 Sample D 40 30
Percent Finer (%) 20 10 0 1 Diameter (mm) 0.1 0.12-0.068 mm 0.01 Durability Properties
Resistance to weathering
Resistance to microbiological degradation (soil burial)
Resistance to liquids
Resistance to hydrolysis
Resistance to thermal oxidation Durability Properties
Geosynthetics may be used for temporary structures such as access roads for construction sites or may be required for medium term applications until consolidation of soils makes them redundant.
Long-term applications are the main use (30 to 60 years for some in UK application or ; more than 120 years for landfills in most countries).
Therefore durability is an important requirement.
Resistance to Weathering (prEN 12224 : 1996)
Products exposed uncovered to light and products placed without cover-soil for service are tested by artificial weathering. Exposure to UV-light of defined emission spectrum and rain at elevated temperature accelerates the test.
Exposure to Natural Weathering Tensile tests after exposure and reference to fresh specimen tensile strength loss in %. Tensile tests on exposed and fresh specimens can be used to determine the loss of tensile strength, normally expressed as a percentage of strength retained after exposure. Rainsplash erosion testing Typical engineering properties of geotextiles used in geotechnical applications (after Lawson 1982)
Geotextile type Mass per Unit Apparent Volume water Tensile Maximum area (g/m2) Opening size permeability Strength kN/m Elongation (AOS) (mm) 1/m2/s %
Woven • Monofilament 150-300 0.07-2.5 25-2000 20-80 9-35 • Multifilament 250-1300 0.2-0.9 20-80 40-800 9-30 • Tape 90-250 0.05-0.10 5-15 8-90 15-20
Nonwoven • Heat-bonded 70-350 0.01-0.35 25-150 3-25 20-60 • Needle-punched 150-2000 0.02-0.15 25-200 7-90 50-80
Knitted • Weft 0.1-1.2 60-2000 2-5 300-600 • Warp 20-120 12-15
Stitched-bonded 250-1200 0.07-0.5 30-80 30-1000 8-30 Application
Geotextile as reinforcement
Designing for Roadways reinforcement Unpaved and paved roads
Designing for soil reinforcement Geotextile reinforced wall Geotextile reinforced foundation soil Geotextile to improve bearing capacity Geotextile encase columns, A continuously, radially, woven geotextile sock Geotextile to in situ slope stabilization made from a variety of polymers. These socks form encased stone columns when filled with compacted sand, gravels or crushed rock for use in very soft soil where conventional ground treatments cannot be utilized. http://www2.wrap.org.uk/downloads/MRF116_Geosystems_Guidanc e_Document_FINAL_February_2010.adb44eaf.8590.pdf Basic Principles of Reinforced Soil
For reinforced soil to work, the soil and reinforcement must STRAIN In a stable structure the strain in the soil and reinforcement are equal (i.e. there is strain compatibility) The strain in the reinforced soil is influenced by:
The stiffness of the reinforcement Properties of the soil The stress state of the soil Analysis and Design
Established geotechnical and stability methods used Soil parameters generally considered in total stress terms Three main failure mechanisms considered
- Rotational Stability - Lateral Sliding - Bearing Capacity Lateral Sliding Embankment fill
Horizontal Reinforcement movement of fill, driven by active wedge Tr Tr
Soft Clay Foundation Reinforcement tension develops in the plane of the reinforcement
Resistance to lateral sliding determined from active driving force Geosynthetics/soil interface should be obtained from testing Foundation Extrusion Embankment fill
Lateral extrusion of foundations due to Reinforcement settlement of fill
Soft Clay Foundation
The solution to this mode of failure is to reduce the settlement by making the base stiffer (Geocell mattress)
If soft soil thickness > embankment base width, a bearing capacity analysis will be required If soft soil layer thickness < than the embankment base foundation width extrusion occurs at the toe.
Case Study: Hetaoyu Coal Mine Processing Plant
Location: China Retaining wall (1km x 140m) built adjacent to Jinghe River PET geotextile used to reinforce soil http://www.geosyntheticsmagazine.com/articles/0212_fla_hetaoyu_mine.html High strength geotextiles for embankments on soft ground
35 June 8, 2002 Case Study: Levee WBV-72
Location: New Orleans, LA Levee (2.8miles long) has 2.4miles of geotextile reinforcement Geotextile strengths used: 490 kN/m (21,500 sq yd) 650 kN/m (187,403 sq yd) 830 kN/m (172,071 sq yd) Used as embankment reinforcement and separation http://www.geosyntheticsmagazine.com/articles/081712_huesker_levee.html Case Study: Levee WBV-72 cont.
http://www.geosyntheticsmagazine.com/articles/081712_huesker_levee.html Case Study: Fiber-Reinforced Roadway Embankment Soil
Location: Lake Ridge Parkway, Texas Originally constructed in the reservoir of a proposed lake (1980s) Earth fill embankments were built (slope ratio=3) to raise road over lake Slope failures occurred (2000s) Repaired with fiber-reinforced soil 3” polypropylene fibers used to increase shear strength http://www.geosyntheticsmagazine.com/articles/0811_f2_sustainable_embankment.html
Case Study: Fiber-Reinforced Roadway Embankment Soil cont.
http://www.geosyntheticsmagazine.com/articles/0811_f2_sustainable_embankment.html Case Study: Fiber-Reinforced Roadway Embankment Soil cont.
http://www.geosyntheticsmagazine.com/articles/0811_f2_sustainable_embankment.html Geotextile as filter or drain Pavement Topsoil
Stone 450 mm base
GT 400 mm Crushed Soil subgrade stone/ perforated 300 mm pipe
(GT Filter in Excavated Trench) (Crushed Stone & Perforated Pipe) Geotubes in Dewatering Applications
Municipal Paper Sludge Pulp and Paper Mill Sludge Mineral Processing Sludge Fly Ash Mining and Drilled Waste Industrial By-Product Agriculture Waste Case Study: Dewatering Solutions cont.
Location: Midlands, England Pumping sludge into filtration geosynthetic tubes (“Sedi-Filter”) Sediment remains but water drains out Sediment removed to landfill Ideal before attempting to deepen canals
http://www.geosyntheticsmagazine.com/articles/101310_sediment_bag.html Case Study: Dewatering Solutions
http://www.geosyntheticsmagazine.com/articles/101310_sediment_bag.html Waste Containment Liners with Geotextiles
Different Drains
Mebra Drain Amerdrain
Installation Prefabricated Vertical Drains
PIPING SYSTEM Application – Seperation
Geotextile as a separator
http://www.typargeotextiles.com/PDFs/TG- Landfills.pdf Erosion Control
Slope Protection with Geotextile
Silt Fence South Channel
A3
A2
A1 Case Study: Incheon Grand Bridge
Location: Incheon, South Korea Reclamation dikes had to be built during construction Geotextiles were used Cost-efficient Met construction and time requirements Close-ended fabric tube with filling ports for sand input Cost more than $2 million http://www.geosyntheticsmagazine.com/articles/0211_fla_incheon_bridge.html
Case Study: Incheon Grand Bridge cont.
http://www.geosyntheticsmagazine.com/articles/0211_fla_incheon_bridge.html Case Study: PEMEX Marine Facilities
Location: Tabasco, Mexico Beach erosion problems Sand-filled geotextile tubes used under oil conduction pipes in the surf zone Previously at risk to collapse due to loss of sand foundations Geotextile tubes also used as a submerged breakwater along the coast http://www.geosyntheticsmagazine.com/articles/0410_f3_tubes.html Case Study: PEMEX Marine Facilities cont.
http://www.geosyntheticsmagazine.com/articles/0410_f3_tubes.html Future Trends and Innovative Products
Reactive Core Mat Intelligent Geotextiles- Geo detect System- Structure Health Monitoring System http://remediation.cetco.com/LeftSideNavigation/Pro http://boingboing.net/2012/01/19/intelligent-geotextiles- ducts/ReactiveCoreMat/tabid/1359/Default.aspx wired.html Future Trends
DUAL FUNCTION GEOSYNTHETICWRAPPED PVD Provides structural stability due to the high tensile and shear strength of the geosynthetic Can bear the shear stresses generated by the mandrel Reduces the zone of disturbance and remolding Also reduces the effects of smear by preventing the finer soil particles to enter the drain core
ELECTRO-CONDUCTIVE PVD Employs the process of electro-osmosis in attempting to reduce the smear effects cations in the diffused double layer of water moves towards the vertical drain (acting as cathode) and get discharged, thus carrying the pore water along with for drainage. Innovative Products and Future
The use of flat weft knitting technology to manufacture natural fiber geotextiles for reinforcement applications
Superior over mid range synthetic geotextile used for soil reinforcement
(Anand,2008) Innovative Products and Future
Reducing fiber diameter to nanoscale, a significant increase in specific surface area to the level of 1000m2/g
Future geotextiles could be nanocomposites which might not only change their effectiveness, but applications (Ko 2004, Koerner 2000)
Innovative Products and Future
By taking advantage of the recent development and changes in design aspects, companies have increased weights from 16 oz. / sy. to 28-32 oz. / sy. Use of polyester for manufacturing of geotextiles has many advantages over traditional polypropylene
(“Advancements in geomembranes and geotextiles” – Reuben Weinstein) Case Study: TenCate Mirafi H2Ri
Location: Alaska Water-wicking geotextile used below roads in frozen tundra Road damage common due to uneven soil moisture freezing differently Tested on the Dalton Highway and now used in Alaska and Canada
http://www.geosyntheticsmagazine.com/articles/102611_tencate_award.html Case Study: TenCate Mirafi
H2Ri cont.
http://www.geosyntheticsmagazine.com/articles/102611_tencate_award.html CIVIL Draintube© FTF Embankment drainage
• Replaces traditional granular layers and two geotextile filters • Can replace up to 3 ft. of granular drainage • Effective solution for cuts, fills and soft soils
Portneuf / mer – Road 138 : Quebec – sept. 2008 Autouroute 50 CIVIL Major project in 2009 with Transports © Draintube FTF Québec Embankment drainage 2,5 km of road
Installation Backfill
The entire job Afitex - 20+ years in the drainage & environmental markets
Texel - 40+ years in geosynthetics
Draintube© technology Geosynthetic Instrumentation Conclusions Questions
What are three different types of geotextiles that can be used for civil engineering applications? What are the most important properties of the geotextiles when they are used as a reinforcing member? What is the difference between index and performance test? Where would you get the information about the geotextile’s properties? Give two specific examples where geotextiles is used as a filter and as a separator. Give example of two innovative geotextilse that have been developed recently.