Hiley’s formula is a widely used method for designing H-piles, accounting for approximately 90% of cases. However, it’s important to recognize its limitations. According to GEO (1996), the formula is only applicable to piles shorter than 30 meters and performs optimally in coarse-grained soils, not fine-grained ones.
The principle behind Hiley’s formula lies in observing the pile’s penetration after hammer impact. By analyzing the response to the impacting force, the pile capacity can be estimated, providing a dynamic assessment of individual pile performance.
However, real-world scenarios often involve groups of H-piles acting together in a foundation. Even if individual piles demonstrate sufficient capacity using the dynamic method, the underlying soil may not be able to support the entire group simultaneously. This discrepancy necessitates the use of static methods to verify the overall bearing capacity of the soil foundation and ensure it can adequately support the combined load of the H-pile group.
In conclusion, while Hiley’s formula is a valuable tool for individual pile design, it’s crucial to complement it with static analysis when dealing with H-pile groups. This dual approach guarantees a comprehensive assessment of both individual pile capacity and the overall foundation’s ability to withstand the intended loads.