Outline of pile foundation load test

The pile foundation load test is to determine the limit load according to the soil foundation of the pile corresponding to the expected design depth, thereby officially deciding the mass cast pile length and pile layout diagram. Load testing of pile foundations is carried out according to the following content:

Outline of pile foundation load test

1. DYNAMIC TEST
1.1 Number of piles to test the pile foundation load: write the number of test piles, with attached drawings
1.2 Pile foundation load test specifications
Pile type: Use M300 reinforced concrete pile, cross section 25 cm x 25 cm
Pile length: L = 24 m, including 2 segments in a combination of 12 m (head segment) + 12 m (nose segment)

1.3 Pile tip height: Estimated – 18.80 m
1.4 Technical requirements when testing the pile foundation load

Preparation for pile foundation load testing
– The test pile driving platform must be prepared to be sufficiently rigid so that it does not shake during driving, which would reduce the impact energy of the hammer.
– Type of hammer: Use an impact hammer with a falling weight of 1800 kg to 2500 kg and a minimum impact energy of 4000 kgm.
– Pile quality: piles must be manufactured according to the design drawings and must undergo quality inspection before driving.
Regulations while pile foundation load test

– When the pile tip is still 1 meter away from the planned design elevation, but the refusal has already reached 2 mm/stroke.
– When the pile tip has reached the planned design elevation and the refusal reaches 2mm< e ≤ 4mm
– When the pile tip reaches the planned design elevation but the resistance is still greater than 4mm/stroke, driving must continue until one of the following two conditions is met:

Density e ≤ 4 mm
Maximum additional closing length is 1 m

Regulations when pile foundation load test
– Wait 3 days after the pile driving is finished, then hammer again with 3 rounds of hammering, 20 blows each round.

– Conditions for concluding pile foundation load testing: The refusal of the pile after re-tapping must reach 2mm to 3mm/per tap. If the above refusal is not met, inform Party A and the design agency to coordinate corrective action.

– Document all pile driving activities from the start of pile driving to the completion of the test pile work, under the supervision of the supervising consultant.
The implementation of test pile driving will be approved by the competent authority

2. STATIC TEST
The pile foundation load test aims to determine the limit load according to the soil foundation of the pile corresponding to the expected design depth, thereby officially deciding the mass cast pile length and pile layout diagram. Test pile pressing is carried out according to the following content:

2.1 Test method: static test
2.2 Test pile
Reinforced concrete pile M300, size 25×25 cm. Length = 30m (combined 10m + 10m + 10m tip sections)
Pile structure: as shown in the drawing

Piles used for pressing must have a complete factory history, ensuring quality and strength according to the prescribed design.
Pile tip height:
Calculated load capacity of pile Ptt = 30 T
Number of test piles

2.3 Test pile location: see attached drawing
2.4 Select pressing equipment
Based on the test load of 50 T, a hydraulic pile jacking device with a minimum pile pressing capacity of 70 T will be selected.

The accuracy of the pile head displacement meter is required to be at least 0.01 mm. The pressure gauges must be inspected by a specialized agency immediately before the load test.
The positioning system, jacking and pressing piles must meet the requirements: keep the pile position stable on the ground.

2.5 Sequence of pressing and static testing
a) Pressing sequence
Condition for stopping pressing:
– The pile tip reaches the planned design elevation of 25.75 m and the minimum driving force is 50 T.
– The driving force must reach a minimum of 50 T, and the pile must be driven into the good soil layer for a distance of at least 1 m (the depth of immersion in good soil is assessed through the jacking pressure: calculated from the moment the jacking pressure increases dramatically, expected to be around 40 T or more).

Note:
– The jacking and pile driving positioning system must be accurate, properly aligned with the pile center, and not exert lateral pressure on the pile head.
– The pile driving and joining process is carried out in strict accordance with the procedures and requirements of the pile driving process.
– Record the change in compressive force during each 1-meter interval.
– When the pile makes good contact with the soil (sudden increase in force and > 40 T), record the change in compressive force in each 20 cm segment.

b) Static suicide sequence
c/ Notes
Condition for increasing load level: load is increased by one level if after one hour of observation the pile settlement is less than 0.20mm and gradually decreases after each reading in the above time period.

Record the load and settlement during the loading process
– Every 15 minutes during the loading period
– Every 30 minutes during a loading period of 1 to 6 hours
– Every 60 minutes during loading times >6 hours

Record load and settlement during load reduction: Load, settlement and time are recorded immediately after being reduced to the corresponding level and as soon as starting to reduce to the new level.
Unloading conditions
– When the load reaches 50T and the load holding time is as prescribed.
– When at any load level less than 50T, the total settlement caused by the test load exceeds 45 mm, or the settlement after 1 hour of observation following the specified holding time is greater than 0.2 mm and increases gradually after each reading within that time period.

Contact information:

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• Phone number: 0915.611.337 Mr. Phuong or 0915.411.337 Mr. Quan
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