Geotextile Engineering : Application in Civil and Environmental Engineering. Shobha K. Bhatia Syracuse University, New York

Transcription

1 Geotextile Engineering : Application in Civil and Environmental Engineering Shobha K. Bhatia Syracuse University, New York ASCE Expo 2012

2 Outline Introduction History Classification Properties Applications Innovations Conclusions

3 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.

4 ZIGGURAT woven mat reinforcement Ziggurat of Ur in Mesopotamia ~ 2500 B.C.

5 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.

6 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.

7 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.

8 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/m 2. Continuous trickle of clean water for 35 years. At the same time, ICI started producing thinner heat bonded nonwoven geotextiles

9 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.

10 VALCROS DAM, 55 ft (1970) First Dam with Geotextile Filter

11 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.

12 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.

13 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 Stitchbonded

14 Geotextile Classification

15 Types Woven- weave pattern and fiber Plain Weave, Basket Weave, Twill Weave, satin weave Warp Threads Non-woven -Spun Bonding Weft Thread Polymer Chip Weaving Direction Fiber Bonding Knitted seldom used Winding

16 Fibers Geotextiles are made of synthetic fiber Polypropylene (92%) Polyster (5%) Polyethylene (2%) Nylon (1%)

17 Slit Film Tapes Yarns Different types of yarn Monofilament fibers Heterofilament fibers Multifilament yarns Staple fibers Slit-film tapes Fibrillated yarns Multi Filament Yarns

18 Different Type of Geotextiles

19 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

20 RECPs wood excelsior wood/synthetic blend straw/coir Coir Coir Jute

21 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

22 Geotextile consumption Year Millions of square meters,north America Million of square meters, Western Europe Million square meters, Japan App (all geosynthetics) Growing market in China and India

23 Relative importance of geotextile functions in geotechnical applications Application Separation Filtration Reinforcement Drainage Protection Temporary and permanent pavements Asphalt overlays Railways Embankment Retaining walls and slopes Erosion control Subsurface drainage 3 1 Membrane protection 3 1 (1) Primary Function (2) Secondary Function (3) Tertiary Function

24 Geotextile Properties

25 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

26 Sampling Measuring (mua)

27 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

28 Mechanical Properties Testing machine with video-extensometer Capstain clamp for geogrid with laser-extensometer

29 Tensile Tests ε

30 Force - Strain behaviour of Geosynthetics Fm kn/m Woven Fabrics, GeoGrids PP/ PE - T PP - M PP/ PET - T HD PE - M strain %

31 Tensile Creep and Creep Rupture EN ISO : 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.

32 Multiple Creep Rupture Rigs in a Temperature Controlled Chamber

33 Resistance To Static Puncture Static Puncture Test: The Test CBR (EN ISO : 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.

34 CBR - device in testing machine Inserting specimen in hydraulic CBRclamps

35 Impact Resistance Test (CEN TC 189 WI 14; ISO 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.

36 Impact Resistance Test Drop weight, lead platen, specimen under ring

37 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 kg 2 m The Test Result of drop tests - no penetration

38 Abrasion Resistance (EN ISO : 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

39 Specimen before test Specimen after abrasion test

40 Direct Shear Friction (EN ISO : 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 ) 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

41 Section Through Shear box Test

42 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

43 Material Before (left) and After (right) Damage Test

44 Characteristic Opening Size (EN ISO : 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 O 90- is calculated according to EN ISO O 90 = d 90 of the soil passing the geosynthetic

45 Dry Sieving Hoop sizing Sagging Broken and irregular glass beads Trapping within the geotextile Electrostatic effects Time for the Test

46 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

47 Pores with Glass Beads Plan view Side view

48 Percent Finer (%) Product: Texel, 909 PET/PP, Staple, Needlepunched, Nonw oven Thickness: 2.3 mm Permeability: 0.45 cm/sec AOS: mm (Dry Sieving) Bubble Point: mm O95: mm O50: mm Mineral Oil Silw ick Porew ick W2 - multifilament Diameter (mm) 0.01 Pore size, volume, permeability, density, surface area, and adsorption

49 Comparison of Wet Sieving & Bubble Point Method 100 Bubble Point Method: 0.12 mm Percent Finer (%) Amoco 4510 Sample A Amoco 4510 Sample B Amoco 4510 Sample C Amoco 4510 Sample D Diameter (mm) mm 0.01

50 Durability Properties Resistance to weathering Resistance to microbiological degradation (soil burial) Resistance to liquids Resistance to hydrolysis Resistance to thermal oxidation

51 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.

52 Resistance to Weathering (pren : 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.

53 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.

54 Rainsplash erosion testing

55 Typical engineering properties of geotextiles used in geotechnical applications (after Lawson 1982) Geotextile type Mass per Unit area (g/m 2 ) Apparent Opening size (AOS) (mm) Volume water permeability 1/m 2 /s Tensile Strength kn/m Maximum Elongation % Woven Monofilament Multifilament Tape Nonwoven Heat-bonded Needle-punched Knitted Weft Warp Stitched-bonded

56 Application

57

58 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 to in situ slope stabilization Geotextile encase columns, A continuously, radially, woven geotextile sock 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. e_document_final_february_2010.adb44eaf.8590.pdf

59 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

60 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

61 Lateral Sliding Embankment fill Horizontal movement of fill, driven by active wedge Tr Tr Reinforcement 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

62 Foundation Extrusion Embankment fill Lateral extrusion of foundations due to settlement of fill Reinforcement 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.

63

64 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

65 High strength geotextiles for embankments on soft ground 35 June 8, 2002

66 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

67 Case Study: Levee WBV-72 cont.

68 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

69 Case Study: Fiber-Reinforced Roadway Embankment Soil cont.

70 Case Study: Fiber-Reinforced Roadway Embankment Soil cont.

71 Geotextile as filter or drain

72 Stone base Pavement Topsoil 450 mm Soil subgrade 400 mm 300 mm GT Crushed stone/ perforated pipe (GT Filter in Excavated Trench) (Crushed Stone & Perforated Pipe)

73 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

74 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

75 Case Study: Dewatering Solutions

76 Waste Containment Liners with Geotextiles

77 Different Drains Mebra Drain Amerdrain

78

79 Installation

80 Prefabricated Vertical Drains

81 PIPING SYSTEM

82 Application Seperation

83 Geotextile as a separator Landfills.pdf

84 Erosion Control Slope Protection with Geotextile Silt Fence

85 South Channel A3 A2 A1

86 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

87 Case Study: Incheon Grand Bridge cont.

88 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

89 Case Study: PEMEX Marine Facilities cont.

90 Future Trends and Innovative Products Reactive Core Mat ducts/reactivecoremat/tabid/1359/default.aspx Intelligent Geotextiles- Geo detect System- Structure Health Monitoring System

91 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.

92 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)

93 Innovative Products and Future Reducing fiber diameter to nanoscale, a significant increase in specific surface area to the level of 1000m 2 /g Future geotextiles could be nanocomposites which might not only change their effectiveness, but applications (Ko 2004, Koerner 2000)

94 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 oz. / sy. Use of polyester for manufacturing of geotextiles has many advantages over traditional polypropylene ( Advancements in geomembranes and geotextiles Reuben Weinstein)

95 Case Study: TenCate Mirafi H 2 Ri 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

96 Case Study: TenCate Mirafi H 2 Ri cont.

97 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

98 CIVIL Draintube FTF Embankment drainage Autouroute 50 Major project in 2009 with Transports Québec 2,5 km of road Installation Backfill The entire job

99 Afitex years in the drainage & environmental markets Texel years in geosynthetics Draintube technology

100 Geosynthetic Instrumentation

101 Conclusions

102 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.