Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 27:Geogrid properties

The Lecture Contains:

Applications

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_1.htm [10/12/2011 11:50:57 AM]

Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 27:Geogrid properties

Geogrids

Its utilization is reinforcement applications. Geogrids are net like material with large Open spaces called apertures, 0.5 to 4 inch between ribs. Primary function is reinforcement application .

Types of Geogrid

(1)Tensar Geogrid

Figure 27.1Made by Tensor Corp, U.S.A

● Uniaxially and biaxially oriented geogrids● Begins as a geomembrane sheet and has a uniform and controlled pattern of pre punched holes.

(2)Tenax Geogrids

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_2.htm (1 of 2) [10/12/2011 11:50:58 AM]

Objectives_template

Figure 27.2

Made by Tenax Corp

Tenax draws their punched sheets mechanically rather than by rolling.

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_2.htm (2 of 2) [10/12/2011 11:50:58 AM]

Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 27:Geogrid properties

Geogrids

Allowable Strength:

F.S = Factor of safety

The laboratory generated tensile Strength is an ultimate value, Which must be reduced before being used In design.

= ultimate tensile strength from a standard in isolation test

= Allowable tensile strength for final design purpose.

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_3.htm [10/12/2011 11:50:58 AM]

Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 27:Geogrid properties

Geogrids

Physical properties:

Structure:

● Intersecting strips● Woven● Woven & Knit● Punched sheet

Polymer:

● Polyester● Poly thylene● Poly propylen

Aperture size Thickness

Mechanical properties:

Tensile strength

shear strength

= Angle of shearing resistance soil to soil

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_4.htm (1 of 2) [10/12/2011 11:50:58 AM]

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Figure 27.3

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_4.htm (2 of 2) [10/12/2011 11:50:58 AM]

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Module 9:Design methods of Geotextiles and Geogrids Lecture 29:Geogrid properties

Geogrid

Figure 27.4

A =Total anchorage strength.

= Longitudinal rib shear strength.

= Transverse rib shear strength .

= Transverse rib bearing strength.

The anchorage strength or pull out resistance is a result of three separate mechanisms

● Shear strength along the top and bottom of the longitudinal ribs of the Geogrid.● Shear strength along top and bottom of the tranverse rib.● Passive resistance against the front of the transverse ribs.(soil goes into a passive state and

resists pull out by means of bearing capacity)

Geogrid

Environmental properties:

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_5.htm (1 of 2) [10/12/2011 11:50:59 AM]

Objectives_template

● Chemical Effects● Biological Effects● Temperature effect● Weathering Resistance

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_5.htm (2 of 2) [10/12/2011 11:50:59 AM]

Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 27:Geogrid properties

The Lecture Contains:

Applications

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_1.htm [10/12/2011 11:52:44 AM]

Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 27:Geogrid properties

Geogrids

Its utilization is reinforcement applications. Geogrids are net like material with large Open spaces called apertures, 0.5 to 4 inch between ribs. Primary function is reinforcement application .

Types of Geogrid

(1)Tensar Geogrid

Figure 27.1Made by Tensor Corp, U.S.A

● Uniaxially and biaxially oriented geogrids● Begins as a geomembrane sheet and has a uniform and controlled pattern of pre punched holes.

(2)Tenax Geogrids

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_2.htm (1 of 2) [10/12/2011 11:52:44 AM]

Objectives_template

Figure 27.2

Made by Tenax Corp

Tenax draws their punched sheets mechanically rather than by rolling.

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_2.htm (2 of 2) [10/12/2011 11:52:44 AM]

Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 27:Geogrid properties

Geogrids

Allowable Strength:

F.S = Factor of safety

The laboratory generated tensile Strength is an ultimate value, Which must be reduced before being used In design.

= ultimate tensile strength from a standard in isolation test

= Allowable tensile strength for final design purpose.

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_3.htm [10/12/2011 11:52:44 AM]

Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 27:Geogrid properties

Geogrids

Physical properties:

Structure:

● Intersecting strips● Woven● Woven & Knit● Punched sheet

Polymer:

● Polyester● Poly thylene● Poly propylen

Aperture size Thickness

Mechanical properties:

Tensile strength

shear strength

= Angle of shearing resistance soil to soil

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_4.htm (1 of 2) [10/12/2011 11:52:44 AM]

Objectives_template

Figure 27.3

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_4.htm (2 of 2) [10/12/2011 11:52:44 AM]

Objectives_template

Module 9:Design methods of Geotextiles and Geogrids Lecture 29:Geogrid properties

Geogrid

Figure 27.4

A =Total anchorage strength.

= Longitudinal rib shear strength.

= Transverse rib shear strength .

= Transverse rib bearing strength.

The anchorage strength or pull out resistance is a result of three separate mechanisms

● Shear strength along the top and bottom of the longitudinal ribs of the Geogrid.● Shear strength along top and bottom of the tranverse rib.● Passive resistance against the front of the transverse ribs.(soil goes into a passive state and

resists pull out by means of bearing capacity)

Geogrid

Environmental properties:

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_5.htm (1 of 2) [10/12/2011 11:52:45 AM]

Objectives_template

● Chemical Effects● Biological Effects● Temperature effect● Weathering Resistance

file:///D|/Dr.patra/ground_improvement_techniques/lecture27/27_5.htm (2 of 2) [10/12/2011 11:52:45 AM]