$matTag

Unique material object integer tag.

$soilType

qzType = 1 Backbone of q-z curve approximates Reese and O'Neill's (1987) relation for drilled shafts in clay.

qzType = 2 Backbone of q-z curve approximates Vijayvergiya's (1977) relation for piles in sand.

$qult

Ultimate capacity of the q-z material. Note that "q" or "qult" are stresses [force per unit area of pile tip] in common design equations, but are both loads for this uniaxialMaterial [i.e., stress times tip area].

$z50

Displacement at which 50% of pult is mobilized in monotonic loading. Note that Vijayvergiya's relation (qzType=2) refers to a "critical" displacement (zcrit) at which qult is fully mobilized, and that the corresponding z50 would be 0. 125zcrit.

$suction

Uplift resistance is equal to suction*qult. Default = 0.0. The value of suction must be 0.0 to 0.1.*

$c

The viscous damping term (dashpot) on the far-field (elastic) component of the displacement rate (velocity). Default = 0.0. Nonzero c values are used to represent radiation damping effects.*