Table of Ultimate Friction Factors for Dissimilar Materials
Values of the angle δ for different interfaces (according to the NAVFAC standards)
Interface material | Friction factor tg(δ) | Friction angle δ [°] |
Mass concrete on the following foundation materials: | ||
Clean sound rock | 0.70 | 35 |
Clean gravel, gravel-sand mixtures, coarse sand | 0.55 - 0.6 | 29 - 31 |
Clean fine to medium sand, silty medium to coarse sand, silty or clayey gravel | 0.45 - 0.55 | |
Clean fine sand, silty or clayey fine to medium sand | 0.35 - 0,45 | 19 - 24 |
Fine sandy silt, nonplastic silt | 0.30 - 0.30 | 17 - 19 |
Very stiff and hard residual or preconsolidated clay | 0.40 - 0.50 | 22 - 26 |
Medium stiff and stiff clay and silty clay | 0.30 - 0.35 | 17 - 19 |
Steel sheet piles against the following soils: | ||
Clean gravel, gravel-sand mixtures, well-graded rock fill with spalls | 0.40 | 22 |
Clean sand, silty sand-gravel mixture, single size hard rock fill | 0.30 | 17 |
Silty sand, gravel or sand mixed with silt or clay | 0.25 | 14 |
Fine sandy silt, nonplastic silt | 0.20 | 11 |
Formed concrete or concrete sheet piling against the following soils: | ||
Clean gravel, gravel-sand mixture, well-graded rock fill with spalls | 0.40 - 0.50 | 22 - 26 |
Clean sand, silty sand-gravel mixture, single size hard rock fill | 0.30 - 0.40 | 17 - 22 |
Silty sand, gravel or sand mixed with silt or clay | 0.30 | 17 |
Fine sandy silt, nonplastic silt | 0.25 | 14 |
Various structural materials: | ||
Dressed soft rock on dressed soft rock | 0.70 | 35 |
Dressed hard rock on dressed soft rock | 0.65 | 33 |
Dressed hard rock on dressed hard rock | 0.55 | 29 |
Masonry on wood (Gross grain) | 0.50 | 26 |
Steel on steel at sheet pile interlocks | 0.30 | 17 |