Gabion Wall Design

Gabion Wall Design

ε Course 1 Course 2 Course 3 Course 4

α

Course 5 O β

Input Parameters Wall Batter angle α Effective plane of rear wall β Slope of Retaining fill ε Properties of Back Fill Density ϒs Soil Friction angle Φ Wall Friction angle δ Soil Friction for foundation δf Geotextile to be used Consider Weight of soil for stability Properties of Gabion Wall Density of Gabion Wall ϒg Dimensions of Gabion Wall Course 1 2 3 4 5 6 7 8 9 10 base Surcharge Po

= = =

0 deg. 81 deg. 0 deg.

= = = =

18 30 27 30

kN/m3 deg. deg. deg.

Yes  Yes 

No No

=

23 kN/m3

Height

Width 0.6 0.5 1 1 1 1 1 1

Offset 0.4 0.8 1.25 1.5 2 2.5 3 4

= =

0.9 0.5 0.5 0.5 0.5 0.5 0.5 0

4m 10 KN/m2

Coulomb's Analysis Coefficient of Active Thrust ka

ka

=

=

0.387

Active Thrust due to soil Pa soil = Pa surcharge Pa

= =

Pa soil +Pa surcharge

=

175.401 kN/m run

=

27.449 kN/m run

=

202.851 kN/m run

Resolving Pa into the horizontal and Vertical Thrust Ph

= =

Pv Pa

164.110 kN d

Pv

Ph

= =

119.233 kN β

Considering Inclination as Zero Coarse Width Height Area

Weight

1 2 3 4 5 6 7 8 9 10

0.4 0.8 1.25 1.5 2 2.5 3 4 0 0

0.6 0.5 1 1 1 1 1 1 0 0

0.24 0.4 1.25 1.5 2 2.5 3 4 0 0 14.89

5.52 9.2 28.75 34.5 46 57.5 69 92 0 0 342.47

Soil Fill Over 1 Over 2 Over 3 Over 4 Over 5 Over 6 Over 7 Over 8 Over 9 Over 10

0 0 0 0 0 0 0 0.5 0 0

0 0.6 1.1 2.1 3.1 4.1 5.1 6.1 0 0

0 0 0 0 0 0 0 3.05 0 0 3.05

0 0 0 0 0 0 0 54.9 0 0 54.9

Center of gravity of Gabion wall, xg = Area Moment Area yg

=

Area Moment Area

Offset Center of Gravity From O x-x y-y 0.9 1.1 0.5 0.9 0.5 1.125 0.5 1.25 0.5 1.5 0.5 1.75 0.5 2 0 2 0 0 0 0

0.9 0.5 0.5 0.5 0.5 0.5 0.5 0 0 0

1.3 1.3 1.75 2 2.5 3 3.5 4.25 0 0

=

1.698

=

2.519

6.8 6.25 5.5 4.5 3.5 2.5 1.5 0.5 0 0

6.8 6.25 5.5 4.5 3.5 2.5 1.5 0.5 0 0

Correcting for Wall inclination Xg =

xg cos α

+

yg sin α

=

1.698

Check for Overturning Effective height to the point of Active Thrust dh soil = H/3 = due to inclination, dh =

dh soil

2.367

-

b*sin α

=

2.367

Overturning Moment Mo

=

Ph

* dh

=

388.393

Resisting Moment 1. Due to Vertical Component of Active thrust MR 1 Where bv

= =

Pv * bv bw cos α

-

dh soil

=

3.625

Area Moments x-x y-y 0.264 1.632 0.36 2.5 1.40625 6.875 1.875 6.75 3 7 4.375 6.25 6 4.5 8 2 0 0 0 0 25.28025 37.507 0 0 0 0 0 0 0 233.325 0 0 233.325

0 0 0 0 0 0 0 1.525 0 0 1.525

tan β MR 1

=

432.237 KNm

2. Resistance due to Self weight of the Gabion Wall Wg Xg MR2

= = =

Total Resisting Moment =

342.47 kN 1.698 m Wg * Xg

581.4458 KNm

=

MR1 + MR2

=

1013.683 KNm

Factor of Safety Against Overturning =

Resisting Moment Overturning Moment 2.609942

= The Section is Safe against overturning, FOS >2 Check for sliding Sliding Force T

= =

Horizontal component of the active thrust Ph = 164.110 KN

Normal force to the plane of sliding (N) N = Wg = 461.703

kN

Horizontal Sliding Force = =

T cos α 164.110

kN

Resisting Vertical Force against sliding N cos α = Fv = 461.703

kN

δf δf

=

+

Pv

-

N sin α

+

T sin α

Foundation Friction Angle =

Hence Resultant Resisting force against Sliding Fv tan δ Fv' = =

30 deg.

266.5641

Factor of Safety Against Sliding FOS

=

Resisting Force Sliding Force

=

1.624305

The Section is Safe against sliding FOS >1.5 Check for Bearing Eccentricity on the base e = e

=

B/2

-

MR - Mo N

0.645687 m

Eccentricity Falls within the One third rule Direct Stress

=

=

=

N A 115.426

σd Bending Stress

=

6N*e

=

115.4257 KN/m2

kN/m2 111.7933

σb

=

bd2 111.793

σ max

=

σd

=

227.219

=

σd

=

3.632

σ min

kN/m2 +

σb

KN/m2 kN/m2

σb