lotrak podrecznik projektanta.pdf

design guide

GEOTEXTILES

stronger by design

FM 23905

A GEOTEXTILES DESIGN GUIDE

First Edition

1984

This guide follows the logical sequence of design:

Second Edition

1989

• Select the relevant chapter,

Revision

1992

• Assemble the required input data,

• Follow the design procedure,

Third Edition

1994

• Write the speciﬁcation.

Revision

1997

Fourth Edition

2003

Back-up theory is available for those wishing deeper examination.

Whilst the intention of this guide is to be as helpful as possible and the

information is offered in all good faith to enable a reasonable assessment of

the practical performance of a geotextile to be made the authors, publishers

and geotextile manufacturers cannot accept responsibility as the conditions

of use are beyond their control. Purchasers and speciﬁers of any geotextile

must statisfy themselves that it is ﬁt for the intended use.

CONTENTS

NOTATION

1 UNPAVED ROADS

1.1 Design Theory

1.2 Input Information

1.3 Design Procedures

1.4 Model Speciﬁcation

1.5 References

2VED ROADS

2.1 Recommendations

2.2 Model Speciﬁcation

2.3 Design Considerations

2.4 References

3 DRAINAGE

3.1 Geotextiles as Filters

3.2 Design Procedure

3.3 Model Speciﬁcation

3.4 Drainage Applications

3.5 Example

3.6 Typical Lotrak Drainage Geotextiles

3.7 References

4OSION CONTROL

4.1 Introduction

4.2 Design Theory

4.3 Design Procedure

4.4 Model Speciﬁcation

4.5 Soil Erosion

4.6 Example

4.7 Typical Lotrak Erosion Control Geotextiles

4.8 References

5 SOIL REINFORCEMENT

5.1 Introduction

5.2 Embankments

5.3 Walls and Slopes

5.4 Design Example

5.5 Model Speciﬁcation

5.6 Remedial Slope Works

5.7 Typical Lotrak Reinforcing Geotextiles

5.8 References

6EOTEXTILE DATA

NOTATION

width

drain width

embankment crest width

C v

coefficient of consolidation

m 2 /year

CBR

California Bearing Ratio

c’

effective cohesion

kPa

c u

undrained shear strength

kPa

C uo

undrained shear strength at ground surface

kPa

depth of drain

D e

equivalent stone diameter

depth to aquifer or length of drainage path

d k

channel diameter

H m

d 1

required draw down

d 90 ,d 60

a size which 90%, 60% etc. of soil particles are smaller than

H m

equivalence factor for axle loads or soil erodibility factor

—

precipitation rate

m/sec

factor of safety

—

G s

speciﬁc gravity of rock

—

height of embankment, wall, slope or waves

H o

upper limit of pavement thickness reduction

granular layer thickness

or artesian pressure head

h o

granular layer thickness

h o

unreinforced pavement thickness

∆ h

reduction in pavement thickness using reinforcement

or hydraulic head

geotextile secant modulus or

kN/m

general coefficient of earth pressure

—

K a

coefficient of active earth pressure

—

K ∆

damage coefficient

—

K b

coefficient of permeability for granular drainage blanket

m/sec

k g

geotextile permeability

m/sec

k s

coefficient of permeability for soil

m/sec

annual soil loss by erosion

tonnes/ha

or soil reinforcement length

turning moment (kN/m x m)

number of passes of a standard axle

—

N f

number of stress application

—

number of axle passes or

—

number of log-cycles of time or

—

geotextile porosity or

—

embankment slope deﬁned as

—

1 vertical to n horizontal

0 90 ,0 60 etc

a size which 90%, 60% etc. of geotextile pores are smaller than

H m

axle load or

erosion protection factor

—

P standard

standard axle load

p t

tyre pressure

kPa

pressure or stress

N/mm 2

drain capacity

m 3 /sec

Q L

line load

kN/m

Q p

point load

unit ﬂow rate

m 3 /sec/m 2

q 0

surcharge load

kPa

rainfall erosity factor

—

or radius

rut depth

r u

pore water pressure ratio

—

slope length and steepness factor

—

or drain spacing

or vertical reinforcement spacing

load or tensile force in geotextile

kN/m

thickness of drainage blanket

or time

years

t g

thickness of geotextile

coefficient of uniformity

—

U’

linear coefficient of uniformity

—

pore water pressure

kPa

velocity

m/s

velocity

m/s

weight of soil mass

or weight of armour stone

tonnes

weight of armour stone

variable length along base of embankment

depth below top of ﬁll or ground level

angle of stress distribution or

bond adhesion factor

—

slope angle

unit weight

kN/m 3

or partial factor

—

γ s

speciﬁc weight of rock armour

tonnes/m 3

angle of friction between geotextile and ﬁll

∈

tensile strain in geotextile

η n

permeability reduction factor for unwoven geotextiles

—

η w

permeability reduction factor for woven geotextiles

—

angle between vertical and slip circle radius

angle between basal reinforcement and tangent to slip circle

rate of increase of undrained shear strength with depth

kPa

mathematical constant

—

settlement beneath centre of embankment

soil stress

kPa

φ 1

effective peak angle of shearing resistance of soil

φ 1 cv

effective angle of shearing resistance of soil at constant volume

φ 1 u

undrained angle of shearing resistance of soil

factor related to rut depth and wheel geometry

—

time from end of embankment construction when basal

years

reinforcement load becomes zero

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