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Transcript of Different Types of Geosynthetics and Their - · PDF fileDifferent Types of Geosynthetics and...
GEOSYNTHETICS AND REINFORCED SOIL STRUCTURESREINFORCED SOIL STRUCTURES
Different Types of Different Types of Geosynthetics and Their
Applications
K. Rajagopal, ProfessorDepartment of Civil EngineeringDepartment of Civil Engineering
IIT Madras, Chennaie-mail: gopalkr@iitm ac ine mail: [email protected]
RECAP OF PREVIOUS LECTURERECAP OF PREVIOUS LECTURE
• Introduction• Introduction• Historical background• Early applications• Functions of geosynthetics• Functions of geosynthetics• Types of geosynthetics
2/52Types and Functions of Geosynthetics
OUTLINE OF 2nd LECTUREOUTLINE OF 2 LECTURE
• TYPES of geosynthetics• TYPES of geosynthetics- - - - CONTINUED
• TYPICAL APPLICATIONS
3/52Types and Functions of Geosynthetics
TYPES OF GEOSYNTHETICS
• GeotextilesG id• Geogrids
• Geonets• Geomembranes• Pre-fabricated vertical drains (PVD)Pre fabricated vertical drains (PVD)• Geosynthetic Clay Liner (GCL)
G ll (3 d fi t)• Geocells (3-d confinement)• Geocomposites & Geo-others
4/52Types and Functions of Geosynthetics
GEONETSGEONETS• Geonets are also planar products• Consists of ribs in two directions• Apertures are of diamond shape• Ribs in the two directions are at different planes• Thickness of geonets is larger than that of g g
geogrids• Geonets are also referred to as geospacersg p
5/52Types and Functions of Geosynthetics
TYPICAL GEONETS
Ribs at two Ribs at two horizontal planes
6/52Types and Functions of Geosynthetics
GEONET APPLICATIONS
• Erosion control – ribs act as small check dams to slow down the surface runoff – decreases erosion potentialrunoff decreases erosion potential of waterD i l fl l• Drainage layers – water flows along the geonet because of large thickness
7/52Types and Functions of Geosynthetics
Boulder net laid on Konkan railway line in Western ghats – functions as guide for loose boulders and vegetation support
8/52Types and Functions of Geosynthetics
Laying of boulder net
Vegetation growth after two seasons
Courtesy: M/s Garware Wall Ropes Ltd., Pune
9/52Types and Functions of Geosynthetics
Anchor trench at the top of the slope 1m deep 0 5mthe slope, 1m deep, 0.5m wide, filled with soil
10/52Types and Functions of Geosynthetics
GEOMEMBRANES
• Thick impervious plastic sheets• Thickness 5 mm to 3 mm approximately• Thickness .5 mm to 3 mm approximately• To contain liquids and gases
Ro gh s rface te t re Smooth do ble sided membraneRough surface texture Smooth – double sided membrane
11/52Types and Functions of Geosynthetics
APPLICATIONS OF GEOMEMBRANESGEOMEMBRANES
• Landfill lining• Landfill lining• Canal lining• Tunnel lining
12/52Types and Functions of Geosynthetics
Geomembrane in a landfillGeomembrane in a landfill
13/52Types and Functions of Geosynthetics
Canal lining using geomembranes
geomembrane Anchor trenchConcrete lining of surface
g Anchor trench
14/52Types and Functions of Geosynthetics
Tunnel lining for moisture t tiprotection
15/52Types and Functions of Geosynthetics
Pre-fabricated vertical drainst l t th lid ti to accelerate the pre-consolidation
of soft clay soils
cT vt %)(UfT
dcT v
v 2 )(fT v
T = time factor
dTd
2
Tv = time factort = timecv = coefficient of
lid ti
cdT vt consolidation
d = drainage path lengthU% = degree of consolidationcv
16/52Types and Functions of Geosynthetics
Reducing the flow path length to accelerate rate of consolidationaccelerate rate of consolidation
surcharge fill
Highly permeabledrainage drainage medium
17/52Types and Functions of Geosynthetics
PVDs for pre-consolidationPVDs for pre consolidation
Corrugated plastic core for drainage
L
tt
Geotextile filter
18/52Types and Functions of Geosynthetics
Pore water flows laterally
Connection arrangements for wick
Pore water flows laterally to the wick drains and is carried through the core
drain installation
19/52Types and Functions of Geosynthetics
Installation of PVDs at a construction site – notice the ti f PVD ith th h l tconnection of PVD with the anchor plate
20/52Types and Functions of Geosynthetics
PVD b i h d i t th dPVD being pushed into the ground21/52Types and Functions of Geosynthetics
General view after installation of PVD’s at a siteGeneral view after installation of PVD s at a site22/52Types and Functions of Geosynthetics
Geosynthetic Clay Liners
• Consist of a core of bentonite clayConsist of a core of bentonite clay sandwiched between layers of thick non-woven geotextileg
• Applied below and above geomembranelayers in landfillsy
• Self-repair mechanism• Bentonite expands when flid leaks throughBentonite expands when flid leaks through
punctured geomembrane – closes the gap
23/52Types and Functions of Geosynthetics
Geosynthetic Clay Linery yGeotextile layers
dry bentonite ypowder
24/52Types and Functions of Geosynthetics
GEOCELL – 3d confinement product
Iso-metric view of a
Plan view showing the mechanism of confinement
geocell layer
25/52Types and Functions of Geosynthetics
Photograph of an expanded geocellPhotograph of an expanded geocell26/52Types and Functions of Geosynthetics
AdvantagesAdvantages• Easy to transportEasy to transport• Any fill material can be used
All d fi t t il• All round confinement to soil• Semi-rigid layer (very stiff support)• Spreads loads over a large area• Excellent support even under cyclic loadsExcellent support even under cyclic loads.
27/52Types and Functions of Geosynthetics
APPLICATIONSAPPLICATIONS
• Erosion controlErosion control• Steep slopes and retaining walls
S b b t• Sub-base support• Road bases
R il t k• Railway tracks• Container yards
28/52Types and Functions of Geosynthetics
Use of geocells for construction of unpaved road Factory
P ti f dStapling to join Stretching of the geocell layerPreparation of groundS ap g o jodifferent geocells
Stretching of the geocell layer
Stone aggregate filled in geocell pockets Compaction by a 10 tonne rollerStone aggregate filled in geocell pockets Compaction by a 10 tonne roller
29/52Types and Functions of Geosynthetics
Geocells used for construction of a steep slope
30/52Types and Functions of Geosynthetics
Vegetation taking root through geocell pockets
31/52Types and Functions of Geosynthetics
IITM students standing on a geocell supported soil
32/52Types and Functions of Geosynthetics
Typical Container yard – heavy loads, usually constructed on soft marine clays near the shorey
33/52Types and Functions of Geosynthetics
Typical mud wave formation in container yards due to heavy l d d t l ft b d illoads and extremely soft subgrade soil
34/52Types and Functions of Geosynthetics
Geotextile separator being laid on the ground surface at a container yard
35/52Types and Functions of Geosynthetics
Geocell layer laid on the geotextile separator and filled with stone aggregate
36/52Types and Functions of Geosynthetics
Container yard 3 years after geocell treatmenttreatment
37/52Types and Functions of Geosynthetics
Some more pictures of the same yard
Perfectly level surface – minor damage in paver blocksy g p
38/52Types and Functions of Geosynthetics
Polymeric erosion control mats
39/52Types and Functions of Geosynthetics
GeocompositesC bi ti f t diff t t f• Combination of two different types of geosynthetics to take advantage of each
40/52Types and Functions of Geosynthetics
Geo-others• Geodrains• Lightweight fillsLightweight fills• Geopipes
G t til b & il l ti• Geotextile bags & soil encapsulation• Gabions• Geosynthetic Encased Stone Columns• Many others – left to the imagination ofMany others left to the imagination of
engineers
41/52Types and Functions of Geosynthetics
Drainage boards for use in Retaining WallsDrainage boards for use in Retaining Walls
42/52Types and Functions of Geosynthetics
Light-weight fill cum drainage medium
Thi k di d f l t b dThick medium made of polystyrene beads43/52
Types and Functions of Geosynthetics
Gabions filled with stones
44/52Types and Functions of Geosynthetics
Gabions filled with sand bags
SAND FILLED GEOBAGS PLACEMENT OF GEOBAGS
TYING OF ROPE GABIONS FINAL VIEW45/52
Types and Functions of Geosynthetics
Light-weight drainage medium
Made of used rubberMade of used rubber tyres and other industrial wastes
46/52Types and Functions of Geosynthetics
Bearing capacity enhanced byEncased Stone Column
Bearing capacity enhanced by
Passive
Geosynthetic Additi l
Passive pressure
+ yencasementAdditional
confinement
Stone column
Sectional plan
47/52Types and Functions of Geosynthetics
Construction of Encased Stone ColumnConstruction of Encased Stone Column
Al i t l (2005)Alexiew et al. (2005)48/52Types and Functions of Geosynthetics
Courtesy:Dipl.-Ing. Holger Pohlmann
Naue Fasertechnik GmbH & Co. KG
P dPresent study
49/52Types and Functions of Geosynthetics
Load settlement curve for stone columns encased in non-woven geotextileencased in non woven geotextile
0 100 200 300 400Pressure (kPa)
0
10
ESC - 50 mmESC - 75 mm
10
20t (m
m) ESC - 100 mm
OSC - 50 mmOSC - 75 mmOSC - 100 mm
30
ettle
men Clay
40
50
Se
5050/52Types and Functions of Geosynthetics
Latest TrendsLatest Trends
• Vacuum consolidation• Vacuum consolidation• Encased stone columns• Electro Kinetic geosynthetics
51/52Types and Functions of Geosynthetics
52/52