CTQP Pile Driving Inspection 2 — Questions and Answers
Question 1: What is a 'test pile' or 'indicator pile' used for on an FDOT project?
- A temporary pile used to guide production pile placement
- A pile driven before production to verify driving criteria and equipment performance (Correct answer)
- A pile used exclusively for load testing
- A sacrificial pile placed to protect the structure from ship impact
Correct answer: A pile driven before production to verify driving criteria and equipment performance
Test or indicator piles are driven before production piling begins to verify that the driving equipment and criteria will achieve the required capacity before full production starts.
Question 2: What hammer type uses a hydraulic mechanism to raise and drop the ram?
- Steam/air hammer
- Single-acting hydraulic hammer (Correct answer)
- Diesel hammer
- Vibratory hammer
Correct answer: Single-acting hydraulic hammer
A hydraulic hammer uses hydraulic pressure to raise the ram and then releases it in a free drop (single-acting) or adds downward hydraulic force (double-acting) to drive the pile.
Question 3: What is the purpose of a 'cushion' or 'capblock' in pile driving?
- To prevent the pile cap from shifting during driving
- To protect the pile head and hammer from impact damage by absorbing energy (Correct answer)
- To seal the top of a hollow pile against water infiltration
- To center the hammer over the pile
Correct answer: To protect the pile head and hammer from impact damage by absorbing energy
A capblock or drive cushion is placed between the hammer and the pile to distribute impact forces and protect both the pile head and the hammer components from damage.
Question 4: What does PDA stand for in pile driving inspection?
- Pile Design Analysis
- Pile Driving Analyzer (Correct answer)
- Penetration Depth Assessment
- Post-Drive Audit
Correct answer: Pile Driving Analyzer
PDA stands for Pile Driving Analyzer, an electronic instrument that measures force and velocity during pile driving to assess pile capacity and driving system performance.
Question 5: At what point during pile driving must the inspector notify the engineer?
- Only after all piles in a bent have been driven
- When a pile reaches refusal before achieving the minimum tip elevation (Correct answer)
- Only when a pile is spliced
- At the start of each day's production
Correct answer: When a pile reaches refusal before achieving the minimum tip elevation
If a pile reaches refusal blow count before reaching the minimum tip elevation specified in the plans, the engineer must be notified immediately to evaluate the situation.
Question 6: What is 'pre-boring' in pile installation?
- Drilling a pilot hole through hard material before driving the pile (Correct answer)
- Installing a test anchor before placing the pile
- Placing grout in the pile bore hole before installation
- Measuring the depth of water before driving marine piles
Correct answer: Drilling a pilot hole through hard material before driving the pile
Pre-boring is the process of drilling a hole through hard material, obstructions, or dense strata before driving the pile to allow it to penetrate to the required depth.
CTQP Pile Driving Inspection 2
What is a 'test pile' or 'indicator pile' used for on an FDOT project?