Behavior of Gravely Sand Using Critical State Concepts

A series of consolidated undrain ed tria xial tests were performed in order t o understa nd t hebehavior of a grave ly sand. th e mat erial was selected from tehran alluvium and is classif iedas gravely sand in t he unified soil classificati on system. criti cal state concept s were used forinterpretation of t he behavior of t he soil. t he criti cal state line in q - p' space was reasonablyunique. however, it was not possible to define a uniqu e crit ical sta te line in e-in p' space. th eoverall scatter, in t he cr it ical st ate line for the gravely sand studi ed, was ± 0.04, in terms ofvoid ratio. two reasons can be ident ifi ed for thi s scatte r. the first reason is t he inevi table errorin void ratio calc ulat ion and th e second is that th e behavior of thi s mat erial, even at a crit icalsta te, is fabric and stru ct ure dependant . on th e basis of th ese tests, it has been concluded t hat,for t his material, a crit ical state zone with upper and lower limits can be defined. neverth eless,a unique boundary surface can be defin ed by present ing th e data in norm alized stress space.