Aeolian Sand Test with True Triaxial Stress Path Achieved by Pseudo-Triaxial Apparatus

Aeolian sand is a special roadbed filler, but its three-dimensional mechanical properties are rarely studied. To obtain the characteristic of its deformation, strength on the deviatoric plane, and failure in three dimensions, a series of triaxial drained tests on aeolian sand in the Tengger Desert, under the condition of the constant average principal stress, p , were conducted by an equivalent alternative method to achieve a true triaxial stress path by a pseudo-triaxial apparatus. The results show that the method can better determine the strength. The peak shear stress decreases gradually with the increase of the intermediate principal stress coefficient, b , at the same p . Compared with the SMP and Mohr–Coulomb criteria, the peak shear stress is near the strength lines predicted by both criteria. At a lower p , the specimen exhibited strain-softening behaviours, but at a higher p , it showed hardening behaviours. Under the conditions of a higher p and lower b , the specimen exhibited contraction first and then dilatancy. The specimen deformation is greatly affected by anisotropy, and as the p- value increases, the effect of the initial anisotropy on the specimen begins to weaken. The ε s (generalized shear strain)/ η (stress ratio)- ε s curves, can be expressed by a linear equation, of which the slope is affected by the b- value. The experiment verifies the feasibility and rationality of the equivalent method. The test data provide support for the maintenance of desert roadbeds and the sustainable development of the economy and society in ecologically fragile areas.