3.1 FIGURE 3.1 below is a drawing of a temporary excavation exposing the existing foundations - NSC Civil Technology Civil Services - Question 3 - 2021 - Paper 1

B is identified as the floor slab.

Two factors that can cause ground movement include:

• Blasting
• Compaction

The slope of the excavation can be deduced as 1:2 or 1:2.

The two acceptable colours for warning signals are:

• Red
• Orange

Two items that should NOT be placed near the edge of an excavation are:

• Any type of load
• Heavy machinery/vehicles

The process of soil compaction involves increasing the density of soil by pressing the soil particles closer together, or reducing the volume of air trapped between the particles using hand compaction methods or a rammer.

Sandy soil is suitable for the use of jetting as a compaction method.

The construction in FIGURE 3.6 is identified as shoring.

The purpose of the sides of the construction is to support the sides of the excavation and to ensure that the sides do not cave in.

The volume of the cylindrical water tank can be calculated using the formula:

$V = ext{Area of base} imes ext{height}$

where ext{Area of base} = rac{22}{7} imes r^2

For given dimensions:

• Diameter = 1,600 mm → Radius = 800 mm → r = 0.8 m
• Height = 3,100 mm → Height = 3.1 m

Calculating gives: $V = (3.14) imes (0.8)^2 imes 3.1 = 6.23 ext{ m}^3$

The formula to calculate the volume of a cubical water tank is:

$V = ext{Area of base} imes ext{height} = S^3$

where S is the length of a side.

To fill a tank of 1 m³, you would need 1,000 litres of water.