A FIBER OPTIC SENSOR TO MEASURE ORTHOGONAL SOIL PRESSURES IN FREEZING AND THAWING SOILS

THE FREEZING/THAWING ENVIRONMENTS OF FROZEN SOILS CONTRIBUTE TO THE POOR DATA PERFORMANCE TO PRESENT FIELD TRANSDUCERS THAT MEASURE LOAD PRESSURES IN SOILS. IMPROVING SOIL PRESSURE DATA OUTPUT FROM DIURNAL, FROZEN SOILS, THAT INCLUDES ORTHOGONAL PRESSURE DATA, WILL PROVIDE BETTER ENGINEERING INFORMATION FOR COLD REGION STRUCTURES. NEW DEVELOPMENTS IN OPTICAL FIBER "SMART" SENSING TECHNIQUES PROVIDES AN OPPORTUNITY TO FORMULATE AND DESIGN NEW PRESSURE SENSORS THAT WILL MEASURE ORTHOGONAL PRESSURES IN FREEZING/THAWING SOILS. SELECTED COMPLIANT MATERIALS WILL BE CONSTRUCTED INTO POLYHEDRON--ELASTOMERICHOUSING STRUCTURES, WHICH CONTAIN EMBEDDED COMPLIANT OPTICAL FIBER MATERIALS, SIZES AND SHAPES. THESE STRUCTURES WILL BE FABRICATED INTO "BREADBOARD MODELS" THAT CONTAIN LEDS AND OPTICAL DETECTORS. LABORATORY TESTS WILL ESTABLISH THE OPTIMUM SENSOR DESIGNS THAT CAN BE MINIATURIZED AND DEVELOPED FOR A PHASE II FIELD PROTOTYPE. PHASE I EFFORTS OFFER THE OPPORTUNITY TO COMBINE OUR NEW NEARINFRARED INSTRUMENT, THAT MEASURES SOIL WATER AND SOIL TEMPERATURE, WITH THE SOIL PRESSURE SENSOR PROTOTYPE. A COMMERCIAL MULTIPARAMETRIC SOIL FIELD INSTRUMENT WILL PROVIDE CIVIL AND STRUTURAL ENGINEERS AND SOIL SCIENTISTS WITH A TOOL TO IMPROVE MONITORING OF FROZEN SOIL PHYSICAL CONDITIONS. IMPROVED SOIL PRESSURE DATA WILL PROVIDE INFORMATION FOR BETTER STRUCTURAL DESIGNS.