SPT N - required fundation
SPT N - required fundation
(OP)
Depth (m) Seating Seating N
1m 1 1 2 3 4 2 ?
2m 2 4 5 6 4 7 ?
I have non experiance with SPT, so i need some help. Here are some results from SPT. How can i determine the size of a foundation reguired to suport a column with a load of 500kN?
THX
1m 1 1 2 3 4 2 ?
2m 2 4 5 6 4 7 ?
I have non experiance with SPT, so i need some help. Here are some results from SPT. How can i determine the size of a foundation reguired to suport a column with a load of 500kN?
THX





RE: SPT N - required fundation
However, some writers have given their opinions as to bearing capacity of differnt soils with varying STP figures.
As you can see these numbers are quite rough to begin with, depending on which set you use. It looks like you are in loose soils. That shoud tell you something.
RE: SPT N - required fundation
In looking at the numbers, though, they may be taking the lead of Tomlinson who a long time ago suggested that you count the number of blows per each 75mm - presuming this to be the case (in that you give two seating blow count values) then the first two would be the seating (2x75=150) and the second pair is the first 150 and the third pair is the second 150 of the 300 - so, if these are blows per 75 mm, then your N value would be 11 at 1m and 22 at 2m. Average these out to say 15; go to Bowles and find the bearing pressure that would be for 25mm of settlement (chart of Size of footing vs allowable bearing pressure for different "N" values. Knowing the allowable bearing pressure, divide the load by it to get the footing area required. Hope your class assignment goes well.
RE: SPT N - required fundation