Micropile design
Micropile design
(OP)
I'm checking a building foundation on micropiles. Soil is a mixture of sand and gravel, weight about 19kN/mc, phi= about 40°; design lenght is about 11m and water table is about 7m under pile cap.
The designer computed an allowable load of about 43tons according to Bustamante & Doix, but I think it is reallly too high for a micropile of 11m, even in gravel.
Depending on different theories I get 15tons to 20 tons allowable load.
Anyway it is the 1st time I heard about Bustamante & Doix. Does anyone know something about it ? Is 43 tons consistent with micropiles ?
Thanks
Ale
The designer computed an allowable load of about 43tons according to Bustamante & Doix, but I think it is reallly too high for a micropile of 11m, even in gravel.
Depending on different theories I get 15tons to 20 tons allowable load.
Anyway it is the 1st time I heard about Bustamante & Doix. Does anyone know something about it ? Is 43 tons consistent with micropiles ?
Thanks
Ale





RE: Micropile design
Besides, sand & gravel is a typical lithology where, by moderately hi-pressure grouting, you can create lateral extrusions along the tubing's shaft which will boost the micropile's capacity.
RE: Micropile design
You really haven't given enough information to evaluate the situation, such as the pile diameter and drilling/grouting procedures. Is 11m the overall pile length, or the bond length?
Today in the US a 43 ton minipile is peanuts. That kind of load shouldn't be hard to achieve in a good gravel/sand layer.
RE: Micropile design
About Bustamante & Doix: their method seems not to take care about water table and it looks quite strange to me.
Greetings
Ale
RE: Micropile design
RE: Micropile design
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there is some reference to Bustamante & Doix, although not extensive.
By the way, I just discovered micropiles are an italian invention (that true?); sure enough, they are used very extensively in Italy, with substantial profit by drilling operators (sometimes cost per lenght unit is greater then in large diameter drilled shafts!)
RE: Micropile design
I'm also not much into micropile design. But anyone know how "popular" this system is in the United States?