Test on engineering properties of unsaturated undisturbed loess Q_2

A series of triaxial shear tests with controlled constant confining pressure are conducted to study the failure modes,effects of deformation,strength and yield properties of unsaturated undisturbed loess Q2,with improved SJ-1A triaxial shear equipment.The test results show that the failure mode of unsaturated undisturbed loess Q2 is shear failure with the rupture angle between 55 and 61 degree;Shear dilatancy is shown under low confining pressure,and shear shrinkage is shown under high confining pressure;The stress-strain curves of undisturbed loess Q2 will change from perfectly plastic to weak strain softening as the confining pressure increases;A effective method is suggested to identify the field stress of undisturbed loess Q2 under triaxial shear condition with the curves of-q/p;when the confining pressure increases,the deviatoric yield stress qy has a logarithmic relationship with net mean yield stress py.