How to work out the quantity of concrete in a trapezoidal retaining wall

In this civil engineering tutorial video, you will get some useful guidelines which can be used to measure the quantity of concrete in a retaining wall.

The retaining wall is constructed in two parts like base slab and stem.

The length of the retaining wall is taken as 15 meter
The breadth is taken as 4 meter
The thickness is taken as 0.5 meter
The height of stem is taken as 4 meter
The top base of stem is taken as 0.5 meter
The bottom base is taken as 1 meter

Based on the above data, the volume of retaining wall will be calculated as follow :-
Volume of retaining wall = Volume of base slab + Volume of stem

Volume of base slab will be calculated with the following formula :-
Volume of base slab = length x breadth x height

After putting all the values, we get the following :-

Volume = 15 x 4 x 0.5 = 30 m³
So, the volume of base slab = 30 m³

The volume of stem will be calculated with the following formula :-
As the stem is in trapezoidal shape, a special formula will be used to calculate the volume.
Volume of stem = trapezoidal area x Length = (a + b/2 xh) x L [here, a = upper base and b = lower base]

After putting all the values, we get the following result :-
Volume = (0.5 + 1 / 2 x 4) x 15 = 45 m³
So, volume of retaining wall = 30 + 45 = 75 m³

So, the quantity of concrete required for this retaining wall = 75 m³

To get more clear idea, go through the following video tutorial.

Video Source: ENGINEERING TACTICS