Deck 6: Foundations

Question 1

Describe how Helical Pier foundations are used.

Answer 1

Helical Pier foundations use helical (screw) steel piers installed at intervals between the footing forms. They are installed by screwing the steel into the soil. The torque required to drive each pier correlates to the bearing capacity of the soil below and is used to ascertain the anchor depth needed to support the required structural load. Helical Piers can also be used to underpin existing foundations that are experiencing settling by using a special support bracket.

Question 2

Explain how post-tensioned steel slabs on grade are created.

Answer 2

Construction of post-tensioned slabs on grade uses high strength reinforcing steel placed inside plastic ducts with tension anchors located in pockets embedded into the slab edge. Once the concrete pour has gained sufficient strength, usually after two to three days, the tendons are stressed. After stressing, the tendon ends are cut off and the anchor pockets filled with grout to protect them from corrosion.

Question 3

____ foundations are formed by boring holes in the earth and filling them with concrete and reinforcing steel .

A) Drilled pile
B) Spread
C) Mat
D) Driven pile

Answer 3

A

Question 4

____ piles utilize heavy-gauge steel pipes that are driven with an open end.

A) H-
B) Precast concrete
C) Pipe
D) Timber

Question 5

Describe how a continuous flight auger is used.

Question 6

____ foundations use long wood, concrete, or steel piles that are driven or drilled into the earth.

A) Pile
B) Spread
C) Mat
D) Driven

Question 7

____ foundations are reinforced concrete slabs several feet in thickness that cover the entire footprint of a building.

A) Pile
B) Mat
C) Spread
D) Driven

Question 8

Describe the most common spread footing.

Question 9

____ hammers use a heavy weight lifted up vertical rails called leads.

A) Diesel
B) Vibratory
C) Single-acting steam
D) Drop

Question 10

Describe how diesel pile hammers are used.