Dilation and particle breakage effects on the shear strength of calcareous sands based on energy aspects

In this paper shear behavior of two calcareous sands having different physical properties are investigated using drained and undrained triaxial tests. The investigated sands are obtained from two different zones located in Persian Gulf, Kish Island and Tonbak region. Analysis based on energy aspects show that friction angle in these soils, having crushable particles, is formed of three components: substantial internal friction angle, dilation and particle breakage angle. Dilation component is available in the two investigated sand. Particle breakage component is a junction of grains hardness, structure and geometry shape. Particles breakage decreases the volume of sample during drained tests and creates position pore water pressure during undrained tests. Two investigated sands show different amount of dilation and particle breakage under similar conditions. Simultaneous dilation and particles crushing and different amount of them result in different shear behavior of the two studied sands. Energy aspects are used to determine the effect of particle crushing on the shear strength. There is a suitable compatibility between relative breakage of grains and consumed energy ratio for particle breakage.