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
Why are ground conditions critical to construction plant stability?
Answer: Soft or unstable ground can cause plant to sink, tilt, or overturn, especially during lifting operations
Ground conditions directly affect whether plant remains stable during operation. Soft ground reduces bearing capacity, causing plant to sink or tilt, which can lead to overturning — particularly dangerous during lifting operations.
What is 'bearing capacity' of the ground and why does it matter for plant operations?
Answer: The maximum load per unit area the ground can support without failing — plant must not exceed this
Ground bearing capacity is the maximum load per square metre the ground can support without failing. Exceeding it causes the ground to collapse, potentially overturning the plant and any load being lifted.
How can outrigger pads help with ground stability during crane operations?
Answer: They spread the outrigger load over a larger area, reducing ground pressure to within the ground's bearing capacity
Outrigger pads spread the crane's load over a larger area, reducing the pressure per square metre on the ground. This prevents the outrigger from punching through and causing the crane to tilt or overturn.
What should be checked regarding underground voids before operating heavy plant?
Answer: The location of any cellars, culverts, tunnels, or buried services that could collapse under plant weight
Underground voids such as cellars, culverts, old tunnels, and drains can collapse under the weight of heavy plant even when the surface appears firm. They must be identified and assessed before plant operates over them.
What is the risk of operating plant on a slope steeper than the manufacturer's specified gradient?
Answer: The plant may overturn laterally or tip forward, causing serious injury or death
Exceeding the manufacturer's specified gradient increases the risk of overturning or forward tipping. The centre of gravity shifts as the slope increases, and beyond the safe limit the plant will roll.
Before placing a crane on outriggers, what ground investigation should be carried out?
Answer: Check for underground services, voids, and confirm ground bearing capacity is sufficient for the outrigger loads
Before deploying outriggers, the ground must be checked for underground services and voids, and the ground bearing capacity must be confirmed as sufficient for the specific outrigger point loads.