Draw a sketch and explain how to find height of chajja or slab using dumpy level.

Draw a sketch and explain how to find height of chajja or slab using dumpy level.
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1 Answer

Answer :

image

Explanation :

1. First the back sight reading is taken on floor level whose RL is known to us; from which RL of instrument axis can be find out by adding RL of BM and BS reading.

2. Now the inverted staff is kept touching to bottom of slab and from same instrument station the reading is taken on it.

3. Then RL of chajja is calculated by adding RL of instrument axis to inverted staff reading.

4. Finally height of chajja is calculated as RL of slab bottom –  RL of floor top.

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