CPCS Ground Conditions & Stability 2

Question 1

What effect does rain have on ground conditions for plant operation?

Accepted Answer

Rain saturates soil, reducing bearing capacity and increasing the risk of plant sinking or overturning

Answer

Rain saturates soil, reducing its bearing capacity significantly. Ground that appeared firm before rain may now be unable to support plant loads, increasing the risk of sinking, tilting, and overturning.

Question 2

Why is it important to position plant away from excavation edges?

Accepted Answer

The surcharge load from plant near an excavation edge can cause the edge to collapse, burying workers below

Answer

Plant near an excavation edge exerts a surcharge load that can destabilise the edge and cause collapse, potentially burying workers in the excavation below. Safe standoff distances must be established and enforced.

Question 3

On a construction site, who is responsible for assessing whether ground conditions are suitable for plant to operate?

Accepted Answer

A competent person — typically a geotechnical engineer or experienced site manager — before the plant is positioned

Answer

A competent person with appropriate knowledge — such as a geotechnical engineer or experienced site manager — must assess and confirm ground conditions before plant is positioned for operation.

Question 4

What is a 'crane mat' and when is it used?

Accepted Answer

A large, heavy timber or steel mat placed under crane outriggers to spread the load on weak ground

Answer

Crane mats are large timber or steel platforms placed under crane outriggers to spread the point load over a larger area, reducing ground pressure to within the site's bearing capacity.

Question 5

What precaution should be taken when operating plant on made ground (filled ground)?

Accepted Answer

Assess the fill material and compaction level, and assume reduced bearing capacity compared to natural ground

Answer

Made ground has variable and often lower bearing capacity than natural ground, depending on fill material and compaction. It must be assessed by a competent person, as it is prone to differential settlement and sudden collapse.

CPCS Theory Practice Test

CPCS Theory Practice Test

CPCS Ground Conditions & Stability 2