In-situ Stress

Techniques and instrumentation for measuring the in-situ stress field in ice are being developed. This project involves laboratory testing and calibration of newly developed stress sensors as well as employing the stress sensors in boreholes drilled into Worthington Glacier. Stress sensors have been tested using a specially designed ice-squeezer at the University of Wyoming, Geology & Geophysics, Cold Research Lab. This apparatus is capable of applying 1.5 tons of tri-axial compression and 1 ton of shear to a 0.3 m³ block of ice. A prototype model of the stress sensing instrumentation package is currently in place on the glacier.

Results of laboratory squeezing of a stress sensor embedded in a block of ice. Horizontal axis is time in hours; vertical axis is pressure in PSI felt by the sensor. Red labels show times when stress was applied to or released from the block of ice.

Instrument package containing stress meters. The unit is designed to freeze itself into a water-filled, 15-cm diameter borehole.