Hyperbolic Model for Load Tests on Instrumented Drilled Shafts in Intermediate Geomaterials and Rock

Analyses of load tests on instrumented drilled shafts in intermediate geomaterials (IGMs) and rock are performed using a hyperbolic model for relative displacement ($\mathrm{\Delta }$)/shaft diameter ($d$)versus side friction ($f_s$) data. Ultimate side friction ($f_{su}$) determined from these analyses for IGMs compares well with those determined from pressuremeter tests. For rock with a rock quality designation (RQD) greater than 50%, values of $f_{su}$ are approximately equal to rock socket unit friction ($q_{SR}$), estimated using 28-day strength ($f_c^{\prime }$) of drilled shaft concrete, but for RQD less than 50%, $f_{su}$ is approximately equal to $q_{SR}$, estimated using uniaxial strength ($q_u$) of rock cores and reduction factor (${\alpha }_E$) to account for jointing in rock. Linear elastic shear modulus ($G$) for IGMs determined from these analyses is approximately equal or slightly less than reload modulus ($G_r$) determined from the pressuremeter test. Rock mass modulus ($E_m$) also matches with values determined from correlations.