| \(A_b\) |
area of pile base |
| \(A_s\) |
area of shaft surface |
| \(B\) |
pile diameter |
| \(c_u\) |
undrained cohesion at the pile toe |
| \(c_{u\text{, avg}}\) |
average undrained cohesion of soil layer |
| \(c_{u\text{, inc}}\) |
undrained cohesion increment with depth |
| \(C\) |
correlation constant for custom weak rock model |
| \({FS}_b\) |
factor of safety for tip resistance (default 3.0) |
| \({FS}_s\) |
factor of safety for skin friction (default 2.5) |
| \(h_\text{penet.}\) |
depth of penetration into the layer |
| \(j\) |
mass factor (function of RQD, see Rock Tomlinson method) |
| \(K\) |
coefficient of lateral earth pressure |
| \(N_c\) |
bearing capacity factor for cohesive soils |
| \(N_q\) |
bearing capacity factor for granular soils (function of shear resistance angle, see Table 1) |
| \(N_\text{SPT}\) |
standard penetration test blow count |
| \(p_a\) |
atmospheric pressure (101.325 kPa or 2116.217 psf) |
| \(Q_a\) |
allowable bearing capacity |
| \(Q_b\) |
ultimate tip resistance |
| \(q_b\) |
ultimate unit tip resistance |
| \(Q_s\) |
ultimate skin friction |
| \(q_s\) |
ultimate unit skin friction |
| \(Q_u\) |
ultimate bearing capacity |
| \(\text{RQD}\) |
rock quality designation (%) |
| \(W\) |
effective pile weight |
| \(\alpha\) |
factor of adhesion (for cohesive soils and weak rock) |
| \(\beta\) |
socket correction factor (Rock Tomlinson method) |
| \(\phi'\) |
effective angle of internal friction for the soil layer |
| \(\sigma_c\) |
uniaxial compressive strength of the weak rock |
| \(\sigma_v'\) |
vertical effective stress at the pile toe |
| \(\sigma_{v \text{, avg}}'\) |
average vertical effective stress along the layer |
| \(\xi\) |
uplift coefficient (default 0.8) |