Meyerhof Method (SPT)
This solution uses a Meyerhof theory, where the bearing capacity of foundation soil is given by a formula:
It is recommended to use a safety factor FS = 3 when calculating the bearing capacity using this method.
Where: | Rd | - | bearing capacity of foundation soil |
N | - | average value of SPT blow counts measured at depths from the footing base to 1.5*bef below the footing base | |
bef | - | effective footing width | |
Cw1,Cw2 | - | GWT influence factors | |
d | - | depth of the footing bottom | |
Ri | - | load inclination factor |
The formula is derived for imperial units [tsf, ft] - the program calculates automatically in the units used in the program.
In saturated very fine or silty sands, the measured SPT blow count for Ni > 15 should be corrected as follows:
This corellation can be performed automatically in the frame "Analysis".
GWT influence factors Cw1 and Cw2 are determined as follows:
hGWT = 0 (water in the terrain level) -> Cw1 = Cw2 = 0.5
hGWT = d (water in the depth of the footing bottom) -> Cw1 = 0.5; Cw2 = 1
hGWT > d + 1,5*bef -> Cw1 = Cw2 = 1
Where: | hGWT | - | depth of groundwater table from the terrain |
Intermediate values Cw1 and Cw2 are interpolated.
Load inclination factor Ri is interpolated according to the following table:
H/V | Ri | ||
d/bef = 0 | d/bef = 1 | d/bef = 5 | |
0.10 | 0.75 | 0.80 | 0.85 |
0.15 | 0.65 | 0.75 | 0.80 |
0.20 | 0.55 | 0.65 | 0.70 |
0.25 | 0.50 | 0.55 | 0.65 |
0.30 | 0.40 | 0.50 | 0.55 |
0.35 | 0.35 | 0.45 | 0.50 |
0.40 | 0.30 | 0.35 | 0.45 |
0.45 | 0.25 | 0.30 | 0.40 |
0.50 | 0.20 | 0.25 | 0.30 |
0.55 | 0.15 | 0.20 | 0.25 |
0.60 | 0.10 | 0.15 | 0.20 |
Where: | H | - | horizontal component of resultant load |
V | - | vertical component of resultant load |
This method should not be used for ratio H/V > 0.6.
The influence of inclined terrain and inclined footing bottom is considered in the same way as in the Schmertmann method.
Literature:
Bridge Engineering Handbook (Wai-Fah Chen, Lian Duan, 1999)