Densification and Shear of Sand during Vibration

by T. Leslie Youd, (A.M.ASCE), Res. Civ. Engr.; U.S. Geological Survey, Menlo Park, CA,

Serial Information: Journal of the Soil Mechanics and Foundations Division, 1970, Vol. 96, Issue 3, Pg. 863-880

Document Type: Journal Paper


The shear strength reduction and density changes that occur in a confined mass of dry, uniformly graded, granular material subjected to horizontal steady-state vibration were quantitatively investigated by testing Ottawa sand and 1/16-in. steel balls in a direct shear apparatus mounted on a shaker table. The samples were first densified until a constant volume state was reached and then sheared while subjected to the same or a less intense vibration. It was found that the constant volume void ratio for samples densified and sheared under the same vibrational conditions; this value decreases with increased vibrational acceleration and is not dependent on frequency. Both the maximum and ultimate coefficients of internal friction decrease with increasing acceleration. Both the interlocking and frictional components of the coefficient are likewise reduced during vibration. An increase of normal pressure tends to counteract the vibrational effects listed above. The behavior noted in these and previous experiments can be explained by mechanisms involving energy barrier concepts.

Subject Headings: Vibration | Shear strength | Shear tests | Soil strength | Granular soils | Sand (material) | Strength of materials | Granular materials

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