Flashcards
Substructure
Cards in this deck (26)
- 1What is included within ground investigations?Site history
Topography tests
Environmental assessments
Ground conditions (bore holes, trial pits)
Water table
Interpretation - 2What is a water table?Variable point at surface water level is positioned, this rises and falls with floods, rain etc. Ground water is any water below the water table
- 3How is the water table lowered during dewatering?1m excavation
6m sheet piles inserted around perimeter of excavation site
dewatering well point pumps are inserted to drain water
Excavation can begin - 4Large projects need an extensive EIA (environmental impact assessment) containing what?Project details
Environment impact analysis (flowers, landscape, wildlife, culture etc.)
Mitigation
Significant effect - 5What are the two types of foundations?Deep
Shallow - 6What are the shallow foundations?Pad
Raft/ Base slab
Strip - 7What are the deep foundations?Pile/Pile caps
Piled walls
Piled rafts - 8What are the two typed of piles?Driven piles (manufactured off site)
Cast In-situ concrete piles - 9How are driven piles placed?Made off site, brought to site, inserted into a piling rig with piling hammer, hammered into the ground
- 10What are the two main types of cast in-situ concrete piles?CFA (continuous flight auger)
Bored piles - 11How do bored piles work?Pre drilling
Drilling commences, temporary casing added and bell out is formed
Hole is cleaned
Reinforcement is added
Concrete is poured - 12How does a CFA work?auger drills into the ground
soil is removed by excavator at the same time
As auger is removed concrete is poured via a hose at the end of the auger
Reinforcement is added - 13How are pile caps installed?Excavation at top of pile cap (1m)
Blind pile caps to show reinforcement
Bend reinforcement down and attach to steel bars
Suspend holding down bolt into position
Add concrete base, secure bolt holes - 14What should be carried out under structures and temporary works?Pilled retaining walls
Excavation
Basement walling
Method statements - 15What are the two typed of piled walls?Secant - alternating concretes poured in the pile holes, reinforced, join to form strong bond
Continuous - Simple reinforced concrete piled walls - 16What are the methods of basement wall construction?Piled walls
Diaphragm Walls
Steel Walls - 17How are diaphragm walls installed?Excavation of ground using hydraulics or pulleys, left, then right, then middle
Bentonite mud is pumped in for support
Reinforcement cage added
Concrete filled from bottom up
Primary panels first, then secondary then closing - 18How are steel walls installed?Interlocking steel panels are driven into the ground via vibrations (sand, clay) or hammered (rock, stone)
- 19Why does casing need to be done carefully?So that there is a watertight enclosure between the basement wall and slab
- 20Why is the sequence of laying a basement slab key?Basement slabs are often large amounts of in-situ poured concrete, the sequence is key to reduce the chance of cracking due to thermal activity whilst laying or drying out
- 21What is required in deeper basements?Deeper basements require temporary support foundations (lateral) to support the walls before the floors are cast in, they are often hydraulic and can be used to adjust the wall if it is not completely straight
- 22How is the propping arranged?Propping is arranged so that it is not in the way for the walls, floor slabs, columns or permanent props, this allows the popping to take the load until the floors are ready
- 23How is top down construction carried out?1. drill piles and plunge columns into wet concrete and add aggregate
2. Cast ground floor slab and excavate underneath through opening
3. Complete excavation and cast lower slab, tie in to plunge
4. Excavate below lower slab for base slab, ensure plenty of ventilation
5. Cast base slab, with pile caps
6. Complete all slabs and infill openings - 24When will top down construction be used?When the site has limited access and space
- 25What are some of the logistic problems in London?Continuous pour requires lots of delivery vehicles in a busy city
Hammer piling is very noisy - 26—
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- Quantity Surveying Flashcards on Substructure, created by Connor Benning on 06/05/2019.
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- Connor Benning
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