Recognition of rapid periodic variations in rock stresses from infrared radiometry data

Physical principles of using measurements of infrared (IR) radiation from r ock surfaces for the detection of changes in their stress state are present ed. The procedure and results of studies designed to substantiate this appr oach are described. The load applied to a sample under conditions of uniaxi al compression varies in time nearly periodically with frequencies of about 1 Hz. A specially designed instrumentation kit can record both readings of strain gages, converted to stress variations, and the related variations i n the IR radiometer signal. An algorithm for the joint treatment of these r ecords is developed. The spectral characteristics of stress variations with time, as determined from radiation and strain measurements, are in reasona ble agreement; when corrected for the time delay of the IR signal, these va riations are nearly identical visually. The results obtained lead to the co nclusion that IR radiometry can effectively detect rapid temporal variation s in the stress state of geomaterials. The potentialities of using this pro cedure in geophysical and geomechanical measurements are discussed.