Substructures

Question 1

Three Types of Soil

Answer 1

Compact (>600)- gravel
Loose Soft (<200)- sand
Soft (<75)- sand

Question 2

Four failures of foundation

Answer 2

Soil movement- soil moving away
Soil failure- overloading and soil falling from beneath
Shear failure- overloaded, better design
Bending failure- overloaded- better design

Question 3

What sort of loads do strip foundations hold

Answer 3

Continuous loads (i.e brickwork)

Question 4

What sort of loads do pad foundations hold

Answer 4

Individual loads (i.e reinforced concrete columns or steel columns)

Question 5

Why would you use a raft foundation?

Answer 5

When the soil conditions are poor and you do not want to excavate too deep

Question 6

Advantages of Pad foundation (3)

Answer 6

Economic
Less excavation
Size and shape can vary

Question 7

Disadvantage of pad foundation (2)

Answer 7

Large pad size if large load

Weak uplift against lateral fources

Question 8

Advantages of raft foundation (4)

Answer 8

When shallow foundaiton is necessary but soil condition is poor
Resists differential settlement
Reduces cost on floor slab
Distributes load

Question 9

Disadvantages of raft foundation (2)

Answer 9

Prone to edge erosion

Special measurements needed when mat foundation subjected to concentrated load

Question 10

Advantages of strip foundation (5)

Answer 10

Ability to withstand great loads
Easy to build
Lower cost than in situ concrete, but not inferior in strength
Better insulation to floors
Long service life

Question 11

Disadvantages of strip foundations (3)

Answer 11

Not suitable for every soil type
Have to fill in one go (concrete availablity)
Needs preparation and help from others

Question 12

Advantages of using piles (3)

Answer 12

Precast to any spec
Screw piles increase in load bearing capacity when driven into soil
Good for using in water environments

Question 13

Disadvantages of using piles (4)

Answer 13

Adaquate reinforcement of precast concrete piles necessary
Adaqueate pre planning is essential
Heavy equipment required
Not suitable for driving in areas with poor drainage
Vibrations in ground affect integrity of other foundations nearby

Question 14

Nine considerations when selecting a foundation

Answer 14

Nature of the load
Ground conditions
Presence of water
Durability of materials
Cost
Accessibility
Sensitivity to noise and vibration
Proximity to other structures
Load exerted on the piles

Question 15

Two types of pile loading

Answer 15

Friction- flat end transmit load directly into groun

End bearing

Question 16

When would you use replacement (bored)

Answer 16

When you need low noise levels and less vibrations

Question 17

When would you use displacement (driven)

Answer 17

If you need piles in water=

Question 18

What is the basics of geothermal piles

Answer 18

Closed loop ground source heat pump
Take heat in and out of the building
Simultaneous power generation and load support for building
Low operating and mainteance