Physical Mechanisms Controlling the Pre-Failure Stress-Strain Behavior of Frozen Sand

• Main Authors: Da Re, Greg, Germaine, John T., Ladd, Charles C.
• Other Authors: MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING
• Format: Text
• Language: English
• Published: 2001
• Subjects: Soil Mechanics; Snow; Ice and Permafrost; Structural Engineering and Building Technology; *SOIL MECHANICS; *FROZEN SOILS; *FOUNDATIONS(STRUCTURES); STRESS STRAIN RELATIONS; SAND; ICE MECHANICS; STRAIN RATE; SHEAR STRESSES; YIELD; TRIAXIAL STRESSES; STRUCTURAL INTEGRITY; YOUNG MODEL; *PREFAILURE BEHAVIOR; Ice; permafrost
• Online Access: http://www.dtic.mil/docs/citations/ADA389159; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA389159

The physical mechanisms controlling the pre-failure behavior of frozen sands are investigated in triaxial compression. The pre-failure behavior (sigma alpha < 1%) is represented by the Young's modulus and upper yield stress. An experimental program conducted on a number of ice-saturated particulate systems investigated the dependency of these parameters on a number of testing variables. Results show that the Young's modulus varies significantly with particle modulus and increases slightly with particle volume fraction, but is independent of strain-rate and temperature. The development of stiffness also relies heavily on the coupling between phases for the transfer of shear stress. This coupling can take the form of an adhesional bond, or a frictional bond derived from particle angularity and surface roughness. Application of reinforcement theories for particulate composites has led to a new approach for predicting the Young's modulus of frozen sand. The upper yield stress behavior is controlled primarily by strain-rate, temperature, particle grain size, and for fully- bonded materials, is essentially independent of volume fraction and confinement. However, in the absence of an adhesional bond, surface roughness and confinement become important. The behavior of the upper yield stress can be explained by examining the influence of particles on cracks propagating through the ice matrix.