This option is required if some or all of the material parameters that define the exponent form of the DRUCKER PRAGER option are to be calibrated from triaxial test data. This option can be used only as a suboption of the DRUCKER PRAGER option.
Set this parameter equal to the value of the material constant a if it is known and is held fixed at the input value. Omit the parameter and its value if a is to be obtained from the calibration.
B
Set this parameter equal to the value of the material constant b if it is known and is held fixed at the input value. Omit the parameter and its value if b is to be obtained from the calibration.
PT
Set this parameter equal to the value of the material constant if it is known and is held fixed at the input value. Omit the parameter and its value if is to be obtained from the calibration.
Data lines to specify triaxial test data
First line
Sign and magnitude of confining stress, .
Sign and magnitude of the stress in loading direction, .
Repeat this data line as often as necessary to give the yield stress at different levels of confining stress.