HOW TO CALCULATE PILE LOAD CAPACITY IN COHESIONLESS SOIL USING SPT OR N-VALUES?

Pile load capacity calculation using standard penetration resistance

This method of calculating the pile load capacity in unconsolidated soils (ie in sand) was suggested by Meyerhof.

Meyerhof suggested the following equation to calculate the final pile load capacity in saturated sand using the standard penetration resistance (N). 1. in the formula below^{scheduled tribe} The end of the term pile gives the bearing resistance and 2^Ra Gives abrasion resistance to the skin of the term pile.

Where,

Why_You = final load capacity of the pile, kN. In

n = average ‘n’ value at pile tip

L = Length of the pile embedded in the soil, m. In

B = diameter or width of pile, m. In

a_P = area of ​​cross section of the top of the pile, m. In²

N’ = Average ‘N’ along the pile shaft

a_s = surface area of ​​pile shaft

notes to remember

1. In any case the end bearing resistance (ie 1 .)^{scheduled tribe} term) 130NA . should be more than_P,
2. The above formula should be replaced by the following formula for non-plastic silt or very fine sand.
3. Safe pile load capacity (q.)_s) can be obtained by dividing the appropriate factor of protection by the final load capacity (Q.)_You) as calculated above, i.e.

Why_s = Q_You /fos

The minimum value of the factor of safety (FOS) is taken as 2.5. But it should be remembered that the value of FOS depends on the following three factors.

• reliability of the formula
• Reliability of Sub Soil Parameters
• acceptable disposal of the structure