Triaxial Constant Strain Rate Tests and Triaxial Creep Tests on Frozen Ottawa Sand.

摘要

Saturated frozen Ottawa sand cylinders and polycrystalline columnar ice were tested in the laboratory under triaxial compressive stress conditions using: (1) constant rate of axial strain,and (2) constant load, i.e. creep tests. The resulting stress-strain curves and Mohr envelopes for the constant rate of axial strain tests indicate that at rates of strain greater than about 0.02per minute,the ice matrix fractures prior to the development of friction between the sand grains. At slower rates of applied strain,the friction between sand grains develops,presumably because ice has sufficient time to creep from between the sand grains. Results from the triaxial creep tests show that creep strength increases with confining pressure and axial creep strain is reduced by increasing the confining pressure. It is suggested that the long-term ultimate creep strength of saturated forzen sand is a function of the internal friction of the sand which could be determined through triaxial tests on freely drained unfrozen sand. (Modified author abstract)