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Experimental method:
 
Compression (load time constant, rapid load, constant speed trans) or hold each level cyclic loading.
 
General requirements:
 
- Includes both pull and compression case.
 
- Conduct at geological sites represents, before construction or during construction.
 
- Number of stakes testing 0.5 (1% of the stakes placed and no less than 03 plants.
 
- The experiment to observe and evaluate the results to be professional staff has extensive experience performing.
 
Technical Requirements Working static load test:
 
- Placement test pile.
 
- Type spindles used.
 
- Dimensions test pile.
 
- Application methods piles.
 
- Preloading method.
 
- Ask about the load capacity of the loading system.
 
- The largest displacement pile is expected, in accordance with loading system and a monitoring system.
 
- Break of the pile after application and load twice.
 
- Other requirements.
 
Level load test:
 
Choose the best PThu how that load level, the stakes were Such slip will reflect more realistic work environment of clay from which more accurate ground Pgh.
 
According TCXDVN 269: 2002; Pmax = 2.5 PTK
 
Currently, many report very little static laboratory test found spindles slip phenomenon when at the level of 10% d download max.Do PThu Pmax = 2.5 Ptkco that the figures probably ground out Pgh not very accurate because not met limit state of soil.
 
Loading system:
 
- The system should pile design load with a load not less than the largest expected load.
 
- If using a ground anchor to form piles loading system, anchored off by at least 5 times the diameter of the pile from the side of the pile.
 
Using a counterweight to compress static:
 
Typically used with counterweight blocks of reinforced concrete.
 
Use anchors to compress static:
 
In some cases cramped space, can not use cranes and concrete counterbalance can use anchors to experiment 04 static compression test the load capacity.
 
The experimental procedure:
 
According TCXDVN 269: 2002 or according to its own standards by Design consultant regulations
Standard TCXDVN 269: 2002 "Pile - Methods of Test by pressing the axial static load" test method specified scene by axial static load applied pressed single pile vertical, oblique irrespective single pile size and method of construction (closed, presses, drills drop, drilling guide, auger ...).
 
In TCXDVN standard 269: 2002 has launched two concepts: Pressed piles probe (compressed 250% -300% destruction) and compression pile test (non destructive compression <= 200%). With destructive compression, we know the real load capacity limit of pile material or ground deformation based on different theories. Also non-destructive compression, we must accept the concept of point destructive conventions of standard regulations to make the load capacity calculations, safety-minded should take full distortion.
 
The order of steps:
 
1. Processing of the pile and put us click.
 
2. handling Sika, creating a flat surface.
 
3. Installation of size and alignment.
 
4. Reinforce the background and installing bearings, load platforms.
 
5. Installation of the main beam, side beams, installing counterweight.
 
6. Install displacement gauges.
 
7. Installation of pumps, hydraulic clock.
 
8. Gia download process and data recording field.
 
Report test results:
 
1. Name and location of works.
 
2. Investors, Consulting design / supervision, construction contractors pile experimental unit.
 
3. Profile pile experiments.
 
4. Data field notes.
 
5. Chart load relations and settlement.
 
6. Chart load relationship, and the time of settlement.
 
7. The remarks while giving the load limit by De Beer, Chin.
 
Ability to satisfy transition biggest pile:
 
- Shift on conventional take 15% plus pile length pile plus elastic deformation allowing transposition of loading system (measuring with an accuracy of 0.1 mm).
 
- Displacement System allows the load: 25 mm for anchors, 100mm loading using beam system.
 
- Ability to load and offload in 10 (25 kN).
 
- Ability to load a minimum of 6 hours.
 
Elastic deformation pile:
 
In the static compression test should consider ourselves elastic deformation Pile. Elastic deformation Pile identified himself as follows:
 
- The coefficient k is reduced compression ratio of the pile contained by stakes in other terrestrial environment compared with the compression formula described in SBVL beam. This coefficient varies according to the work of the pile: pile k = 1, k = 0.5 Friction, has anti-friction medium coefficient k = 0.67 is considered to reduce the power poles along the length of the body due to friction pile close.
 
Preloading process:
 
Compressed tiered piles, to increase the design load. The load is increased new level after 1 hour if subsidence monitoring of smaller piles 0:20 mm and tapered after each reading in time on.
 
Depending on the design requirements, the pile can have 200% load design load. Time at 100%, 150% and 200% can be extended to 12 or 24 hours 6gio.
 
At 100% load level is kept 6 hour load can reduce the load of 0% to monitoring the weak elastic and residual settlement corresponding to the design load.
 
Careful notes while reading experiments and strange phenomena. If you can meet the members of the group to offer reasonable solutions for each of the strange phenomenon.
 
Conclusions on the results of load testing.
 
Bearing capacity of the pile can enable drawn from this experiment:
 
Corresponding load displacement pile is 8 mm divide the 1.25 system.
 
Corresponding load displacement pile pile width of 10%, or the largest load in the experiment achieved divided by a safety factor of 2.
 
Break between piles of construction and try to reach: Intensity material when the pile reinforcement must withstand intense load without destruction; Family vacation time from the time of construction to load for sticky soil, dust is 7 days and sometimes up to 4 weeks.
 
Timesheet effect load levels:
 
% Design load

 

 

Minimum hold time download

 
25
50
75
100
75
50
25
0
100
125
150
125
100
75
50
25
0
1 hours
1 hours
1 hours
1 hours
10 minute
10 minute
10 minute
10 minute
6 hours
1 hours
6 hours
10 minute
10 minute
10 minute
10 minute
10 minute
1 hours
 
Static compression test should be conducted prior to foundation design to not change the parameters of the pile multiply, affecting the work cost and time to solve the problem if there avoid having to stop progress monthly constructed to solve this problem .
 
Picture the scene :
 

 

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