Effect of Normalization on Developing SHANSEP Based Undrained Shear Strengths of Fine-Grained Soils: Fid-Bau Portal

Effect of Normalization on Developing SHANSEP Based Undrained Shear Strengths of Fine-Grained Soils

Ajmera, Beena / Tiwari, Binod / Al-Behadili, Mohammed

The undrained shear strength of normally and overconsolidated clays are required in a number of geotechnical applications including evaluation of the stability for embankments and slopes. While researchers have examined the effect of the overconsolidation ratio on the undrained shear strengths and proposed models such as SHANSEP to estimate the undrained shear strength of fine-grained soils, the influence of mineralogy and plasticity on the undrained shear strength has not been extensively studied. To do so, various mixtures of montmorillonite, kaolinite, and quartz were prepared in the laboratory and consolidated in oedometer to obtain soil samples at overconsolidation ratios ranging from 1 to 32. The undrained shear strengths of these overconsolidated soil samples were then measured using a constant volume simple shear device. As expected, the undrained strength ratio was found to increase as the overconsolidation ratio increases. At a given overconsolidation ratio, the value of the undrained strength ratio was greater for soils with a lower plasticity index. However, the dependence of the undrained strength ratio on the overconsolidation ratio was eliminated by normalizing the measured undrained strength ratios with the undrained strength ratio of normally consolidated soil sample. Unique relationships were developed between the rate of increase of undrained strength ratios with the overconsolidation ratios and plasticity characteristics, separately for high plasticity and low plasticity soils.