a presentation on geo textiles : perspective from the construction sector by d c de consulting...
TRANSCRIPT
A Presentation
On
Geo Textiles : Perspective from the Construction Sector
By
D C DE
CONSULTING ENGINEERING SERVICES (INDIA) PRIVATE LIMITED
FEDERATION OF INDIAN CHAMBERS OF COMMERCE AND INDUSTRY
19 November 2010
Geo Drains Geo Drains Geo SeparationsGeo Separations
MSEMSEReinforcementReinforcement
Geotextile Applications in Roads
ASTM D4439 defined a geotextile as follows
Geotextile : A permeable geosynthetic comprised solely of textiles. Geotextiles are used with foundation, soil, rock, earth, or any other geotechnical engineering-related material as an integral part of a human-made product structure, or system.
Due to the very wide range of applications and the tremendous variety of available textiles having widely different properties, the selection of a particular design method or design philosophy is a critical decision that must be made before the actual mechanics of the design process are initiated.
Geotextile Functions and Mechanisms
An overview of geotextiles, alluded to many applications falling into categories:
Separation
Reinforcement
Filtration
Drainage
Containment
When properly identified, lead to the design-by-function method.
Geotextile choices as available
1. Lightweight Wovens2. Heavyweight
Wovens3. High Flow Wovens4. High Strength
Wovens5. Thermally Bonded
Non-wovens6. Needle punched Nonwovens
Separation
Geotextile Functions and Mechanisms
Bituminious Courses
Aggregate Bases
Geotextile Layer
Subgrade
Filtration and Drainage
Geotextile Functions and Mechanisms
Bituminious Courses
Aggregate Bases
Geotextile Layer
Aggregate Drainage Layer
Subgrade
Reinforcement
Geotextile Functions and Mechanisms
This is the synergistic improvement in the total system strength created by the introduction of a geotextile into a soil and developed primarily through the following three mechanisms:
One, lateral restraint through interfacial friction between geotextile and soil/aggregate.
Two, forcing the potential bearing surface failure plane to develop at alternate higher shear strength surface.
And three, membrane type of support of the wheel loads.
Sealing Function
Geotextile Functions and Mechanisms
New Overlay
Reflective Crack without Paving Fabric
Old Pavement
Base Course
Major Applications of Geotextiles
Separation of Dissimilar Materials
Between subgrade and stone base in paved roads and airfieldsBetween landfills and stone base coursesBetween geomembranes and soil drainage layersBetween foundation and embankment soils for surcharge loadsBetween foundation and embankment soils for roadway fillsBetween foundation and encapsulated soil layersBetween foundation soils and rigid retaining wallsBetween slopes and downstream stability bermsBeneath precast blocks and panels for aesthetic paving e.g. hardscaping
Major Applications of Geotextiles
Separation of Dissimilar materials
Between drainage layers in poorly graded filter blankets Between old and new asphalt layers
Reinforcement of Weak Soils and Other Materials
To reinforce embankmentsTo aid in construction of steep slopesAs basal reinforcement over soft soilsTo bridge over cracked or jointed rockTo create more stable side slopes due to high frictional resistance
Major Applications of Geotextiles
Filtration (Cross-Plane Flow)
Beneath stone base for paved roads and airfields Around crushed stone surrounding under drains Around perforated under drain pipe As a flexible form for restoring scoured bridge pier bearing capacityBetween backfill soil and weep holes in retaining walls Between backfill soil and gabions As a filter beneath precast blocks
Major Applications of Geotextiles
Drainage (In-Plane Flow)
As a drain behind a retaining wall As a drain at the base of retaining wall As a replacement for sand or wick drains
These are geocomposites formed of a hollow cored, geotextile wrapped drainage element (geonet) inserted vertically into soft ground to speed up the consolidation process.
Prefabricated Vertical Drain Installation of PVD
Band Drains / Prefabricated Vertical Drains (PVD)
Band Drains / Prefabricated Vertical Drains (PVD)
Kandla Port – Ground improvement
Band drains has been adopted to increase the bearing capacity of the site. The following parameters have been adopted:
Scheme SBC before
treatment(T/m2)
Spacing of Band Drain
with Triangular
Grid (m)
Preload Height
(m)
Duration(Days)
SBC after treatment
(T/m2)
Scheme-1 2.00 1.25 4.00 80 10.21
Scheme-2 2.00 1.50 4.00 120 10.11
Band Drains / Prefabricated Vertical Drains (PVD) at Kolkata
Emerging Issues
R&D Needs of the Indian Geotechnical Industry
The Need to Encourage the Domestic Synthetic Manufacturing Industry
Need for Establishing a Geosynthetic Institute in India
Standardization in the Field of Geosynthetics
Geosynthetics Test Standards and Specifications