Compressive strength of iceberg ice

The uniaxial compressive strength of iceberg ice was determined over a wide range of strain rates from 10(-8) to 10(+1) s(-1) at -10(degrees)C. It was found that for strain rates less than 10(-4) s(-1), strength increased in a power-law manner with strain rate. Above 10(-4) s(-1), the strength was essentially constant at 4 MPa, dropping slightly between 10(-3) and 10(-1) s(-1), before rising again to a value of about 10 MPa at 10(+1) s(-1). Thin sections of the ice revealed a small grain size of about 3.5 mm and elongated air bubbles with a ratio of length to width of about 10. In the practical strain-rate range of interest, the maximum failure stress observed was 4.8 MPa.