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Hill road earthwork, chainage 0-600 (12 marks)

Short answer

Level-ground sections with A=(B+sh)h, B=10m, cut slope 1.5:1, fill slope 2:1. Mean-area volumes computed from centre heights. Earthwork: cutting 1460.25 m³, filling 2615.50 m³.

Find the quantity of earth work of a hill road from the following data. Formation width is 10 m, side slope in filling and cutting 2:1 and 1½:1 respectively.

Chainage (m)0100200300400500600
RL of Ground (m)1115.201116.101116.851118.001118.251118.101117.75

Formation: RL at chainage 0 is 1116.5 m, upward gradient 1 in 200 up to chainage 300 m. Downward gradient 1 in 400 from chainage 300 m onwards.

Given data and assumptions

  • Formation width B=10B = 10 m; side slope in filling 2:12:1, in cutting 1.5:11.5:1. No cross slope is given, so the ground is level across the road.
  • Formation level 1116.50 m at 0, rising 1 in 200 up to 300 m (1118.00 m) and then falling 1 in 400.

Method

Level (plain-ground) sections are used. With centre height hh, formation width BB and side slope s:1s:1:

A=(B+s h) hA = (B + s\,h)\,h

Volume between two sections = mean area × distance; where a section changes from cutting to filling, the length of each part is found by proportion of the depths and the volume of each part = ½ × end area × length.

ChainageGL (m)FL (m)Depth of cutting / height of filling (m)
0+0001,115.2001,116.500filling 1.300
0+1001,116.1001,117.000filling 0.900
0+2001,116.8501,117.500filling 0.650
0+3001,118.0001,118.0000.000
0+4001,118.2501,117.750cutting 0.500
0+5001,118.1001,117.500cutting 0.600
0+6001,117.7501,117.250cutting 0.500

Sectional areas

ChainageCentre ht. hh (m)Cutting area (m²)Filling area (m²)
0+000fill 1.300.00016.380
0+100fill 0.900.00010.620
0+200fill 0.650.0007.345
0+3000.000.0000.000
0+400cut 0.505.3750.000
0+500cut 0.606.5400.000
0+600cut 0.505.3750.000

Volumes

BetweenDistance (m)Cutting (m³)Filling (m³)
0+000 – 0+100100.00.001,350.00
0+100 – 0+200100.00.00898.25
0+200 – 0+300100.00.00367.25
0+300 – 0+400100.0268.750.00
0+400 – 0+500100.0595.750.00
0+500 – 0+600100.0595.750.00
Total600.01,460.252,615.50

Answer: Earthwork in cutting = 1,460.25 m³; earthwork in filling = 2,615.50 m³.

✓ Answer checked by Claude Opus 5.5 (high effort)

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