ISSN:
1082-5010
Keywords:
shear waves
;
spontaneous liquefaction
;
stability
;
hypoplasticity
;
Engineering
;
Civil and Mechanical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Architecture, Civil Engineering, Surveying
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
A theoretical study of plane shear waves in a fully saturated granular medium is presented using a hypoplastic constitutive relation for the solid constituent. Dynamic equations for small disturbances about an initial state are derived and analysed with constitutive parameters for Karlsruhe sand. Permanent changes in stresses during the propagation of waves are shown to result in the liquefaction of the material. As follows from the equations, in the general case the propagation is characterized by two different wave speeds, corresponding to the plus or minus sign of the velocity gradient, i.e. to different directions of an instantaneous shear. The values of the wave speeds depend on the initial state (stresses and void ratio) as well as on the orientation of the wave with respect to the principal stresses of the initial stress tensor. If the granular material is loose enough and the initial stress state differs from the hydrostatic one, it is possible that one of the wave speeds becomes imaginary, i.e. physically does not exist. This case means a loss of stability of the body in the sense that a small boundary disturbance results in a flow of the whole mass which cannot be prevented by a boundary control. Such a solution can be viewed as a model of spontaneous liquefaction. The condition obtained for stability is compared with the one derived from the analysis of the second-order work.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
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