DEFORMATION BEHAVIOURS OF DRY SAND UNDER CYCLIC LOADING AND A STRESS-DILATANCY MODEL

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概要

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• Cyclic shear stresses, τ, with constant amplitudes are applied to a dry sand up to 1,800 cycles under constant over-burden pressures, p, using the simple shear apparatus in order to clarify the factors affecting the deformation behaviours under cyclic loading. The following results are obtained. The rotation of shearing direction by 90 degrees in the middle of a test does not affect the volume change.The deformation characteristics under cyclic loading are controlled mainly by the stress ratio, τ/p, and are divided into two phases by the stress ratio of critical disturbance (τ/p)_c. Namely, an amount of volume change accumulated during 1,800 cycles of shearing increases abruptly when τ/p≧(τ/p)_c. The influence of an initial structure of grains on the deformation behaviours disappears by repeated cyclic loadings when τ/p≧(τ/p)_c; however, this structure remains intact partially when τ/p<(τ/p)_c. Moreover, the deformation by the stress application after stress reversal is not affected by the stress application before the reversal when tested in the stress range of τ/p≦(τ/p)_c, but affected in range of τ/p>(τ/p)_c. The stress ratio of critical disturbance (τ/p)_c increases as the void ratio of a sample decreases and it can be obtained by static shear tests. A fundamental and unified explanation of these experimental results is given by the two-dimensional stress-dilatancy model which is built on the basis of the concept of shifting the position of the sliding contact point in a limiting equilibrium state. As a result, the stress ratio of critical disturbance can be defined as the stress ratio by which all the points of contact are slid in one cycle, and the following relation can be satisfied : max (τ/p)_c=(τ/p)_<dv=0>=tan θ_μ.

• 社団法人地盤工学会の論文
• 1979-06-15

著者

• 徳江 俊秀

  Civil Engineering Laboratory Central Research Institute Of Electric Power Industry

関連論文

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