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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)

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