The viscoelastic characterization of marine sediment in large-scale simple shear

Abstract

To obtain deformation properties of submarine sediment a device which imposes a simple shear state of strain was designed. A thorough literature review was conducted to evaluate the merits of previously developed simple shear devices. A large-scale simple shear device capable of testing a 24 by 24 in (61 cm) sample with length to thickness ratios of 48, 24, and 12 has been designed and built at Texas A&M University. The apparatus is capable of measuring the stress response of a saturated sample of sediment within a shear strain range of 0.5 to 12 percent. An experimental program using a four-bladed vane shear device and the large-scale simple shear apparatus was conducted to evaluate the viscoelastic properties of marine sediment for use in a wave-sea bottom interaction computer program. Experiments were conducted with the large-scale simple shear device in the cyclic triangle and sine wave displacement modes to check the theories currently used in the program. The former loading mode is used to evaluate the viscoelastic theories for monotonic loading. In addition, the change in sediment properties as a function of the number of strain cycles is also evaluated. The latter loading mode is used to verify and/or modify the cyclic nonlinear viscoelastic constitutive equations currently used in the computer program.