Drained And Undrained Stress-Strain Behavior of Sands Subjected to Cyclic Shear Stress Under Nearly Plane Strain Condition

Abstract

A series of static drained and dynamic undrained cyclic shear tests of complete reversal were conducted to obtain fundamental information about stress-strain behavior of sands using a ring torsion apparatus to apply cyclic shear stresses under nearly plane strain condition. In the static drained tests, the relative density of specimens was ranged from 20% to 85%, and amplitudes of the cyclic shear stress were 0.21 and 0.33 kg/cm2 under effective overburden pressure of 1. 0 kg/cm2. Test results indicated that there were hyperbolic relationships between number of stress cycles N and volumetric strain accumulated up to the Nth cycle, between N and shear modulus in the Nth cycle, and between N and total energy absorbed in a unit volume up to the Nth cycle, irrespective of initial relative density and of shear stress amplitudes. Dynamic undrained test results indicated that the ratio of the increment of pore water pressure per stress cycle to dynamic shear stress amplitude was proportional to the fourth power of dynamic shear stress amplitude to initial effective overburden pressure, for specimens of relative density of about 40%. And this relationship was explained by using the above-mentioned stress-strain behavior of the static drained tests.