Excavations And Ground Support Flashcards
Trench collapse is deadly..
Ground moving and crushing the body would cause suffocation
Cdm regs states who has a role on health and safety on site?
Everyone. All sites no matter what states everyone has a responsibility for h&s
When should the competent person inspect a deep excavation?
At the start and end of every shift
When considering excavations, what should commercial issue to contractors before work begins ?
Ground conditions
Underground structures and watercourses
Trench less techniques should be considered at design stage to minimise risk, but what is the biggest problem with this?
Not always practicable and expense
What should happen with topsoil on a construction site ?
Removed, bunded and reused at a later date
What does formation mean?
Creating a level surface to which you can build
What are the advantages and disadvantages of vertical trench?
Ads
Less reinstatement
Save cost
Disads
May take longer (trench support installation)
What are the advantages and disadvantages of battered trenches ?
Ads
No requirement of temporary support
Disads
More cost for backfill and reinstatement
Space required
Name the 6 reasons why trench support would be required ?
Ground conditions Vibrations Water table (ground waters) Proximity of buildings Period of time left open Safety and Compliance
What is the difference between closed and open timbering
Closed timbering is completely covering the sides of the trench, open is partially covered
Support is provided by combining what materials ?
Poling boards
Runners
Waling
Trench sheeting
What are the advantages and disadvantages of traditional timbering
Ads
Cheap
Readily available
Made to fit
Disads
Limited reuse
Steel trench sheeting advantages and disadvantages
Ads Reusable Greater strength Exclude water ingress Permanent support
Disads
Costly
Sheet piling can be used for perimeter supports such as
Prevent collapsing
Reinforcing sides of excavations
Forming cofferdams
