Deep foundation/soil interfaces are subjected to temperature variations due to seasonal effects, extreme climates, and energy foundation applications. This investigation was conducted to determine the effects of temperature on the interface shear strength between sand and steel. The materials used for the experimental investigation included mild A36 steel to represent pile foundations and medium, well-graded sand. A large-scale interface direct shear apparatus (300 × 300 × 150 mm depth) was used for testing. Tests were conducted at three normal stresses (50, 100, 150 kPa) and at three temperatures (2°C, 20°C, and 40°C). The sand was prepared to a relative density of 75%. The steel plates were analyzed before and after shearing using a noncontact white light optical interferometer to characterize changes in surface texture of the steel due to shearing against sand. Overall, interface friction angle decreased slightly with temperature. Peak interface friction angles were 20.1°, 19.9°, and 19.0° for tests conducted at 2°C, 20°C, and 40°C, respectively. The surface characteristics of the steel plates varied significantly due to shearing at the test temperatures and normal stresses.
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