| A nonlinear finite element model, called MINE-PAL, has been developed for elasto-plastic, large deformation analysis of underground and surface mining excavations. The model accounts for both material nonlinearity due to yielding and strain-hardening and strain-softening effects and geometric nonlinearity due to large deformations. The finite element equations are formulated using incremental plasticity theory with Total Lagrangian approach where the Kirchhoff stress tensor and Green strain increment tensor are used. The model is developed for use on microcomputer system and is designed to perform 2-D nonlinear analysis of mine excavations in multiple-material domain, thus predicting the distribution of elastic, strain-softening, strain-hardening and residual strength zones. The model accommodates any arbitrary stope geometry and it allows for a variety of mining-type loading conditions in situ stresses, gravity loading and boundary tractions. Special provision has been made to permit the simulation of backfill as in situ stress-free material. Stress-space strain-softening is invoked into model using the concept of damage parameter in the incremental stress-strain relation.;In addition to model verification and sensitivity analysis, two numerical modelling case studies have been undertaken. The first case study is of a narrow vein mine with backfill which is located in the province of Karnchanaburi, Thailand. The second case study is about a room-and-pillar design of a potash deposit in the province of Chaiyaphum, Thailand. |
