Static Load Test on Bored Pile (Slow Test or Quick Test) 2

[massagung]

Hi All,

i am begineer in pile testing, i have some question about axial, lateral and uplift load test,

as i know, static load test often combination with instrumentation such strain gages, tell-tales extensometer, pile integrity thermal, and others. the purpose of instrumented test pile are to get more data for estimate true load transfer, settlement along pile, cover concrete along pile and others, which with valid and enough data there is any possibility for optimization of design.

here's my question,
1. What is the consideration of method of load test, when we use slow test (loading-unloading-reloading) and quick test (only loading), i mean beside consider of time, is there any technical reason?
2. Could we conduct quick test in same pile if previously already tested with slow test? whether the data still reliable to analyze (load settlement curve)?
3. I have little experienced about intrumented test pile with strain gages to get load transfer along pile (6 Level), but the Elastic Modulus of pile is too far each other level of one pile (the difference between lower and higher E value about 70%), i analyze using hooke law? is this is possible (with assumstion the data acquicition strain gages reading is valid and actual)?

thanks in advanced,


M.A.

 

[oldestguy]

First of all, look up ASTM standards for Pile Load testing. There you will get some good basic information.
the criteria for acceptability might be found there, but a good practical text, such as Piling engineering", Blackie and son Ltd, London 1985, 1992 tells a lot that you need. Amazon has one left.

Generally, I see no need for a quick test, since in use the loading is slow.

It is pretty much reacquired that the pile contractor furnish all the equipment, except perhaps some dial gages and surveying instruments. You need back up measurements of several types, because there can be practical problems not envisioned ahead of time. I like to have a taught wire strung along the side of the pile or equivalent against a ruler , just in case other methods are damaged or fail.

 

[GeoPaveTraffic]

When testing piles in sand, a quick test is fine and saves money.

When testing piles in clay, we always specify standard loading; i.e. slow tests.

When testing piles on rock, sometimes we use the standard loading and sometimes quick. Depends on the overburden soils and the rock type.

In all cases, we try to to fail the pile. If it doesn't file under the standard load, we will quick load to failure or the capacity of the testing equipment.

Mike Lambert

 

[massagung]

thanks oldestguy for your helpful input, i just read ASTM related that test (D1143-81 for Axial Compression, D-3689-07 for Static Axial Tensile Load Test, and D3966-07 For Lateral test.

thanks Mike, your comment very helpful, i just know that quick test or load test is also depend of soil type.

adding question,
local regulation in my country not acceptable only dynamic method for testing of pile for highrise building (> 8 story) all of test pile have to using static load test (minimum 2/3 from total of test pile, where 1/3 test pile can be tested using dynamic method such statnamic or PDA. how about in your region?


M.A.

 

[oldestguy]

Local regulations vary. In general the number of load tests on piles is established by the geotechnical engineer, considering the soils on the job. In my experience,generally we only test one or two piles per job site. These are single building sites usually under 6 stories. Safety factor is usually at least 2.0 based on a limit of allowable settlement. The production piles are driven to the same indicated resistance as the test piles, usually bay a pile driving formula, as inches per blow. My experience does not include any use of pile analyzer technology.