Step-by-step Calculation of Pile Capacity Using the Static Formula

The static formula is a common method used to determine the load-carrying capacity of a pile. It involves calculating the sum of the skin friction along the pile shaft and the end bearing capacity at the pile tip. This process helps engineers ensure the pile can support the intended load safely and efficiently.

Understanding the Static Formula

The static formula is expressed as:

Q_ultimate = Q_skin + Q_end

Where:

• Q_skin: Skin friction along the pile shaft
• Q_end: End bearing capacity at the pile tip

Calculating Skin Friction (Q_skin)

Skin friction is calculated by multiplying the unit skin friction (f_s) by the surface area of the pile shaft in contact with the soil.

The formula is:

Q_skin = f_s × A_shaft

Where:

• f_s: Unit skin friction (kPa or MPa)
• A_shaft: Surface area of the pile shaft (m²)

Calculating End Bearing Capacity (Q_end)

The end bearing capacity is determined by multiplying the end bearing capacity of the soil (q_p) by the cross-sectional area of the pile tip.

The formula is:

Q_end = q_p × A_tip

Where:

• q_p: End bearing capacity of the soil (kPa or MPa)
• A_tip: Cross-sectional area of the pile tip (m²)

Final Calculation

After calculating both components, sum them to find the ultimate pile capacity:

Q_ultimate = Q_skin + Q_end

This value indicates the maximum load the pile can support based on static analysis.