An original dynamic interpretation of acceleration time-histories recorded during undrained Triaxial Cyclic Tests

摘要

The paper presents the results of laboratory tests carried out on undisturbed specimens of a gravelly soil sampled by in situ freezing. Because of the heterogeneity of the natural deposit, the grain size distribution of the specimens ranged from uniform sand with a very low percentage of gravel to well-graded sandy gravel, and three different soil groups could be defined according to grain size (respectively named A, B and C). The testing programme comprised drained and undrained monotonic triaxial tests and undrained cyclic triaxial tests, carried out on both isotropically and anisotropically (K_0) consolidated specimens. Because of the coarse gradations of the soils, a special large triaxial cell was used. This cell was set up with a wave generator, to apply both shear and compression wave at the base of the specimen, and a devoted acquisition system was set up as well. With these devices, measurements of the soil shear waves velocity (Vs) were achieved, even during the undrained cyclic tests. Thanks to this system it was possible to carry out an original dynamic interpretation of the acceleration time-histories recorded during undrained Triaxial Cyclic Tests.