Ground Conditions & Stability Flashcards
6 cards from real CPCS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Ground Conditions & Stability flashcards as text
What effect does rain have on ground conditions for plant operation?
Answer: Rain saturates soil, reducing bearing capacity and increasing the risk of plant sinking or overturning
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.
Why is it important to position plant away from excavation edges?
Answer: The surcharge load from plant near an excavation edge can cause the edge to collapse, burying workers below
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.
On a construction site, who is responsible for assessing whether ground conditions are suitable for plant to operate?
Answer: A competent person — typically a geotechnical engineer or experienced site manager — before the plant is positioned
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.
What is a 'crane mat' and when is it used?
Answer: A large, heavy timber or steel mat placed under crane outriggers to spread the load on weak ground
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.
What precaution should be taken when operating plant on made ground (filled ground)?
Answer: Assess the fill material and compaction level, and assume reduced bearing capacity compared to natural ground
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.
How does frost affect ground conditions for construction plant operation?
Answer: Frost temporarily strengthens the surface but thawing rapidly reduces bearing capacity — creating dangerous conditions
Frost can temporarily harden the surface, giving a false impression of strength. When thawing occurs — often rapidly — the ground can lose bearing capacity suddenly, creating dangerous conditions for plant operations.