THE DESIGN OF "ROOM AND PILLAR" STRUCTURES IN COMPETENT JOINTED ROCK. EXAMPLE: THE CRESTMORE MINE, CALIFORNIA

A COMPREHENSIVE ROCK MECHANICS RESEARCH PROJECT HAS BEEN COMPLETED WITH RESPECT TO "ROOM AND PILLAR" MINING AT CRESTMORE, CALIFORNIA. SINCE THE MINE HAS BEEN OPERATING FOR AN APPRECIABLE PERIOD OF TIME UNDER SUCH A PATTERN, THIS STUDY IS NOT A "DESIGN FROM SCRATCH." IT REPRESENTS RATHER, A MAJOR EFFORT TO CHECK IF EXISTING CONDITIONS ARE ACCEPTABLE WITH REGARD TO SAFETY, AND TO INSURE THAT FURTHER MINING WILL BE BASED ON THE BEST SCIENTIFIC KNOWLEDGE AVAILABLE TO DATE. PRODUCTS OF THIS RESEARCH ARE, AN INCREASED EFFICIENCY IN THE MINING OF THE ORE BODY AT CRESTMORE, THE REFINEMENT OF PRESENT TECHNIQUES, AND THE PRESENTATION OF NEW PROCEDURES FOR GENERAL MINE DESIGN. THE DIFFERENT PHASES OF THIS PROJECT WERE: (1) A REVIEW OF THE STATE OF THE ART IN ROOM AND PILLAR DESIGN; (2) THE COMPLETION OF TWO SERIES OF IN-SITU EXPERIMENTS ON DIFFERENT LEVELS OF THE CRESTMORE MINE, INVOLVING DEFORMATIONS, STRESSES AND DEFORMATABILITY MEASUREMENTS; (3) THE ESTABLISHMENT OF A COMPLETE "IDENTIFICATION CARD" FOR THE CHINO MARBLE AND ITS DISCONTINUITIES; (4) THE CONSTRUCTION OF MODELS FOR THE MINE BASED UPON NUMERICAL TECHNIQUES USING NEW OR IMPROVED PROGRAMMING OPTIONS; (5) THE DETAILED APPRAISAL OF RESULTS FROM FIELD, LABORATORY AND MODEL WORK IN TERMS OF THEIR INDIVIDUAL AND CORRELATIVE VALUE AND OF THEIR PRACTICAL IMPLICATIONS. /AUTHOR/