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:

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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 floor must be prepared hard enough so that when driving, the driving platform does not shake, reducing the shock energy of the hammer.
– Hammer type: use impact hammer with falling part weight from 1800 kg to 2500 kg, minimum impact energy is 4000kgm
– Pile quality: piles must be manufactured according to design drawings and must be quality tested before driving
Regulations while pile foundation load test

– When the pile tip is 1 m away from the expected design elevation but the rejection has reached 2mm/1 stroke
– When the pile tip has reached the expected design height and the rejection reaches 2mm < e ≤ 4mm
– When the pile tip reaches the expected design height but the rejection is still greater than 4mm/1 stroke, you must continue driving 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 finishing driving the pile, hit again with 3 hammer blows, 20 blows each.

– Conditions for ending the pile foundation load test: Rejection of the pile after reclawing reaches from 2mm to 3mm/1 stroke. In case the above rejection level is not met, it is necessary to notify Party A and the design agency for coordinated handling.

– Record all pile driving progress from the time of starting and lowering the pile until the end of the test pile work, under the supervision of a supervision 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
M300 reinforced concrete pile, size 25×25 cm. L=30m (combination of 10 m + 10 m + 10 m nose segment)
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 expected design height - 25.75 m and the minimum pressure reaches 50 T
– The pressure is at least 50 T and the pile is lowered 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: from the moment the jacking pressure suddenly increases, it is expected to be about 40 T or more)

Note:
– The jack and pile positioning system needs to be accurate, adjusted to the center of the pile and not cause horizontal pressure on the pile head.
– Pile pressing and splicing are carried out in accordance with the correct order and requirements in the pile pressing process.
– Record the pressure evolution in each period of 1 m
– When the pile contacts the soil well (force suddenly increases and > 40 T), record the pressure evolution in each 20 cm section.

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 loading time
– Every 30 minutes during loading time from 1 hour to 6 hours
– Every 60 minutes during loading time > 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 level 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 weight exceeds 45 mm or the settlement after 1 hour of observation after the specified load holding time is greater than 0.2 mm and gradually increases after each reading within the above time period.

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