Research Specifications

The main object of this research is the investigation of the behavior of clay-sand mixtures in undrained condition. For this purpose, the behavior of clay mixed with the different percentage of sand (i.e., 0%, 20%, 40% and 60%) was studied by carrying out undrained triaxial tests on normally consolidated and overconsolidated specimens under different effective stresses. The results showed that sand inclusion up to 20%-40% (depend on sand size) does not affect considerably the shear strength of the clay, but when the amount of sand is more than 40%, the shear strength raises 74% to 260%. Maximum pore water pressure at low confining pressures remains unchanged by changing sand content from 0% to 60%. At high confining stress, this parameter for specimens consist of 40% sand is higher than the corresponding values of the other ones. For overconsolidated specimens, irrespective of some exceptions, dependent on sand size the values of shear strength improve 43% to 73% when sand content varies from 0% to 60%. In addition, deformation modulus of both normally consolidated and overconsolidated mixtures increases 9% to 136% by an increase in sand content from 0% to 40%, and, then, the values diminish rapidly by changing sand content from 40% to 60%.