Strain Softening and Instability of Loose Sand in Plane-Strain Compression Tests

Experimental data to study the strain softening and instability behavior of loose sand under plane-strain conditions are presented in this paper. K₀ consolidated drained and undrained tests under both deformation-controlled and load-controlled loading modes were carried out using a new plane-strain apparatus. The drained and undrained behaviors of very loose sand under plane-strain conditions were characterized. The test results show that the loading mode affects the post-peak behavior of sand and controls whether strain softening or instability will occur in the post-peak region. The failure line and critical state line are not affected by the loading mode.