a presentation on geo textiles : perspective from the construction sector by d c de consulting...

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