Experimental determination of probability distributions for parameters of a Salem limestone cap plasticity model
Abstract
Marginal probability density functions and a correlation matrix are determined for parameters of the Weidlinger cap plasticity model for Salem limestone specimens originating from Bedford, Indiana. The report describes a program comprising precision laboratory testing, parameter estimation, and probability distribution model fitting. A novel testing scheme allows a complete set of material parameters to be determined from a single test specimen. Statistical properties and distributions are determined by replication. The fitted model is validated by predicting loading histories not included in the fitting database. The testing program includes uniaxial strain tests in axial strain control, unconfined compression tests in ail strain control (-1 x 10(exp 6/8)), hydrostatic compression tests in load control (-0.02 MPa/s), and triaxial compression tests in axial strain control (-1 x 10(exp 5/8)), during loading and load control during unloading (-0.02 MPa/s). All specimens are tested at a constant temperature of 20 C and at a water saturation level of 50%. The validation study clearly demonstrates that the parameter estimation procedure produces high quality parameter values, and that the fitted model can not only reproduce measured data included in the fitting database, but also predicts responses from tests conducted under loading histories different from those found in the fitting database.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- January 1995
- Bibcode:
- 1995STIN...9530559F
- Keywords:
-
- Axial Loads;
- Estimating;
- Hydrostatics;
- Limestone;
- Mathematical Models;
- Prediction Analysis Techniques;
- Probability Density Functions;
- Probability Distribution Functions;
- Stress-Strain Relationships;
- Underground Structures;
- Unloading;
- Axial Strain;
- Compression Tests;
- Correlation;
- Data Bases;
- Fitting;
- Matrices (Mathematics);
- Plastic Properties;
- Shear Stress;
- Statistical Distributions;
- Structural Mechanics