below ground Flashcards
What is the substructure?
All structures below ground level, including ground floor slabs and damp-proof course
Its function is to receive loads from the superstructure and transfer them safely down to earth.
Define dead load.
Tiles, roof, truss; all things that aren’t living.
Define live load.
Snow, maintenance, plants/vegetation, weight from living things.
What are bore holes used for?
To sample soil and find the water level of the ground.
List the different types of foundations.
- Strip foundation
- Deep strip foundation
- Pile foundation
- Grillage foundations
- Trench fill
- Raft foundation
- Pad foundation
What is the superstructure?
All structures above substructure both externally and internally
Its function is to act as the external envelope and transfer dead and imposed loadings to the substructure.
What materials are low rise framed structures made from?
- Steel work
- Laminated timber beams
- Mild steel
What is traditional construction made from?
Block and brickwork placed in a reinforced cage, sometimes with concrete.
Define modular construction.
Like shipping containers, made into boxes that can be stacked on each other.
What does ‘insitu’ mean?
Where moldings are put up on site and concrete is poured in.
What factors should be considered before starting work on a site?
- Site location
- Accessibility
- Availability of space
- Services
- Ground composition
- Site clearance
- Demolition
What does subsoil investigation determine?
- Changes in strata
- Strengths of subsoil
- Toxicity of subsoil
- Stability of excavation
- Water table/depth below surface
What is strata?
Layers of different types of subsoil, each with different properties including strength.
What is the purpose of a foundation?
To spread the load from the structure over a safe bearing area of subsoil and provide a stable level base.
Fill in the blank: The topography, type of ground, and ground conditions are part of _______ when choosing soil techniques.
Choosing types of soil techniques.
What is a trial pit?
A trench built/digged out for geotechnical engineers to take soil samples.
What does the standard penetration test (SPT) measure?
Pressure bearing on the soil.
What is vibroflotation?
A method to strengthen soil by vibrating it to increase density.
What is grouting?
Injecting cement-based material into weak soil to fill voids and increase density.
What is blinding?
A thin layer of sand, concrete, or gravel used to smooth and level surfaces.
What is a solid foundation?
One where the ground, structure, and foundation act in harmony.
What are the two types of foundations mentioned?
- Raft foundation
- Pad foundation
How is a raft foundation constructed?
Excavate soil, compact foundation bed, lay concrete blinding layer, install waterproof membrane, add steel reinforcement, pour concrete, and finish with a blinding layer.
What are the benefits of a raft foundation?
- Saves materials and time
- Less excavation
- Reduces differential settlements
How is a pad foundation constructed?
Mark foundations, excavate ground, temporarily support sides, pour concrete, and cast insitu.
What are the characteristics of a short bored pile?
- Goes deeper into the ground
- Reaches certain strata
- Can be cast insitu or precast concrete
What conditions make short bored piles a good choice?
- Uneconomical situations
- Larger piles over 2m in depth
- Poor drainage ground
- High water table
