Experimental study of effect of stress history on mechanical properties of saturated sand under complex stress conditions

The effect of stress history under three dimensional stress conditions are one of the important phenomena which have to be evaluated for the accurate prediction of ground deformation.Various stress-controlled drained monotonic shear tests on the Chinese Fujian standard sand of relative density 30 % under complex stress conditions with different stress paths are conducted using the soil static and dynamic universal triaxial and torsional shear apparatus.The mean principal stress is controlled unchanged in the process of tests.The stress history conditions are varied so that their influences on shear strength and stress-strain relationship of saturated sand are explored.Test results show that under drained condition sand specimens with stress history of different type do not change their shear strength for a given mean principal stress.On the other hand,the stress-strain characteristics behaved differently with respect to the stress history.The elastic locus varied with stress history has directional and stress condition effects.Finally,introducing predominant parameters for the difference of the direction and the stress condition between stress history and shear process,as well as taking into account the experimental results,the elastic boundary space due to the stress history is expressed under three dimensional stress conditions.