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Design of Terraces 1

The document provides details on designing terraces on a hill with a 30% slope to grow kalamansi shrubs. It calculates: 1) The horizontal interval between terraces as 6.667 meters. 2) The length of terrace per hectare as 1,499.925 meters. 3) The earthwork required per hectare as 2,500 cubic meters for a vertical cut and 2,125 cubic meters for a 0.5:1 batter slope. 4) The area lost per hectare is 33.014% for a 0.5:1 batter slope.

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271 views2 pages

Design of Terraces 1

The document provides details on designing terraces on a hill with a 30% slope to grow kalamansi shrubs. It calculates: 1) The horizontal interval between terraces as 6.667 meters. 2) The length of terrace per hectare as 1,499.925 meters. 3) The earthwork required per hectare as 2,500 cubic meters for a vertical cut and 2,125 cubic meters for a 0.5:1 batter slope. 4) The area lost per hectare is 33.014% for a 0.5:1 batter slope.

Uploaded by

ᜁᜊ ᜀᜎᜆᜂ
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Design of Terraces

Suppose a bench terrace is to be constructed on a hill with a 30% slope. The soil type and the
soil depth of the said hill can support the growth of kalamansi shrub. The width of the surface of
bench is 1 m and the vertical distance is 2 m (i) horizontal interval or width, (ii) length of terrace
per hectare, (iii) earth work required per hectare, and (iv) area lost per hectare both for vertical
cut and batter slope of 0.5:1 is shown below.

i) The horizontal interval


100 D 100(2 m)
W= = =6.667 m
S 30
ii) Length of terrace per hectare
10,000 ha
L= =1,499.925 m
6.667 m
iii) Earthwork per hectare
Earth work per hectare=Crosss−sectional area of cut∗length of terrace/ ha
1
∗6.667 m
2
∗2m
2
Earth work /hectare= ∗1,499.925 m=2,499.999 m3 ≈ 2,500 m 3
2
iv) Area lost

Area Lost =
√( D +W
2 2
) −W
∗100=√ ¿ ¿ ¿
√ D +W2
2

When batter slope is ½:1, using equation

2WS
D=
( 200−S )

( 200−S ) D ( 200−30 ) 2m
W= = =2. 83 m
2S 2 ( 60 )
Length per hectare
10,000 10,000
Length per hectare= = =2,309.469 m/h
2.83 m+0.5 m+1 m 2
Earthwork per hectare

Earth work / hectare=


1
2 (( 6.667 m
2 )∗1 m2−
2m
2( ) )
∗0.5 m 2 ∗1,499.925 m=2,125.019m 3 ≈ 2,125 m3

Area lost for cultivation


S +200 30+ 200
Area lost for cultivation= = =33.014 %
200 S 200 30
+ +
S 100 30 100

Other considerations
Reverse height
RH =Width of platform∗10 %=1 m∗0.10=0.1 m

Height of Riser

Verticalinterval+ RH ( 2m+0.1 m )
Hr= = =1.02m
2 2
Width of riser

Wr=Hr∗U ; U=0.75−1
Wr=1.02 m∗1=1.02
Width of ditch
Wt=Width of platform+2 Wr=1m+2 ( 1.02m )=3.04 m

Inclined distance
Verticalinterval
Inclined Distance= =2m/sin 30=4 m
sine of slope

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