• Journal of the Korean Geotechnical Society
• /
• v.26 no.7
• /
• pp.7-16
• /
• 2010

Stress history increases the residual horizontal stress of granular soil and, consequently, the penetration resistance. This study analyzes the effect of stress history on the cone resistance ($q_c$), horizontal stress index ($K_D$) and dilatometer modulus ($E_D$) of CPT and DMT from calibration chamber specimen in OC as well as NC state. Test results show that the normalized cone resistance by mean effective stress correlates well with the relative density and the state parameter, whereas the normalized cone resistance by vertical effective stress is a little affected by stress history. The influence of stress history is more reflected on $K_D$ than $E_D$ and $q_c$. The $K_D/K_0$, in which the effect of stress history on $K_D$ is compensated by the at-rest coefficient of earth pressure, $K_0$, is related to relative density, state parameter and the normalized cone resistance by mean effective stress. It is also observed that the normalized dilatometer modulus by mean effective stress ($E_D/{\sigma}_m'$) shows a unique correlation with the state parameter, regardless of stress history.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.11
• /
• pp.61-72
• /
• 2013

The consolidation tests are conducted to investigate the soil particle crushing stress for understanding the secondary compression characteristics of carbonate sandy sabkha soil caused by particle crushing under a high confining stress. The rate of secondary crushing compression ($C_{{\alpha}{\epsilon}}{^*}$) is introduced instead of the rate of secondary compression to define the characteristic of the particle crushing compression settlement ($S_s{^*}$). Void ratio ($e_p{^*}$) and settlement ($H_p{^*}$) in particle crushing are used as a reference point of secondary behavior, and the ratio of primary compression index ($C_c$) to secondary crushing compression ($C_{{\alpha}{\epsilon}}{^*}$), $C_{{\alpha}{\epsilon}}{^*}/C_c$ value was changed from 0.0105 to 0.0187. When comparing with quartz sands, secondary compression settlement of sabkha is very large due to particle crushing which is not usually observed in quartz sand. It is observed that as the depth of sabkha layer becomes deep, the $S_s{^*}$ and $C_{{\alpha}{\epsilon}}{^*}$ increase under the same stress level.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.8
• /
• pp.125-135
• /
• 2008

Rigid-soft particle mixtures, which consist of sand and rubber, are investigated for the understanding of the stress-deformation and elastic moduli. Specimens are prepared with various size ratio sr between sand and rubber particles, and different volumetric sand fraction sf. Small strain shear waves are measured under $K_o$-loading condition incorporated with the stress-deformation test by using oedometer cell with bender elements. The stress-deformation and small strain shear wave characteristics of rigid-soft particle mixtures show the transition from a rigid particle behavior regime to a soft particle behavior regime under fixed size ratio. A sudden rise of $\Lambda$ factor and the maximum value of the $\zeta$ exponent in $G_{max}=\;{\Lambda}({\sigma}'_{o}/kPa)^{\zeta}$ are observed at $sf\;{\approx}\;0.4{\sim}0.6$ regardless of the size ratio sf. Transition mixture shows high sensitivity to confining stress. The volume fraction for the minimum porosity may depend on the applied stress level in the rigid-soft particle mixtures because the soft rubber particles easily distort under load. In this experimental study, the size ratio and volumetric sand fraction are the important factors which determine the behavior of rigid and soft particle mixtures.