The Undrained Characteristics of Tengger Desert Sand from True Triaxial Testing

Abstract

Aimed at the characteristics of aeolian sand under rapid construction conditions in desert geotechnical engineering, a series of the true triaxial undrained test were carried out on the GDS apparatus. The 3D deformation, failure, and other characteristics of the dense sand are obtained. Under the condition of same p c , the state transition point where the void water pressure changes from increasing to decreasing appears earlier and leads to enhanced dilatancy with the increase of b, which means the enhanced dilatancy of dense sand caused the increase in strength. The results of the same b shows that the void water pressure generally indicates a decrease at low confining pressure and an increase at high confining pressure, indicating that the aeolian sand shows dilatancy at low confining pressure and contraction at high confining pressure. The state transition point increases with the increase of p c , but all points tend to the same critical state line and state transition line. When b = 0, the critical state line is q = 1.57 p ′ , and the state transition line is q = 1.23 p ′ . When b = 1, the critical state line is q = 1.24 p ′ , and the state transition line is q = 1.04 p ′ . The results at same b obtained the unified critical state line and the state transition line. Therefore, the true triaxial test can obtain the unified relationship of void ratio, p c and b, which overcomes the fact that the existing test cannot consider the influence of b. The test results provide a basis data for the design, construction, and maintenance of geotechnical engineering in Tengger Desert.

Cyclic True Triaxial Tests on Aeolian Sand Considering Initial Shear Effect

“…The true triaxial apparatus can load independently on three orthogonal planes of a cubic soil specimen, and the static and dynamic characteristics of soil can be measured in true three-dimensional space [22][23][24]. Three orthogonal principal stress loading proportions are controlled by the coefficient of intermediate principal stress (b = (σ1 − σ3)/(σ2 − σ3)) [25,26]. Based on a series of true triaxial tests, Li et al [25,26] studied the mechanical behavior of saturated aeolian sand under true triaxial conditions, and found that the b had a significant influence on stress-strain, pore pressure, and critical state.…”

“…Three orthogonal principal stress loading proportions are controlled by the coefficient of intermediate principal stress (b = (σ1 − σ3)/(σ2 − σ3)) [25,26]. Based on a series of true triaxial tests, Li et al [25,26] studied the mechanical behavior of saturated aeolian sand under true triaxial conditions, and found that the b had a significant influence on stress-strain, pore pressure, and critical state. Shi et al [22] investigated the influence of b on the stress-strain relationship and strength behavior of coarse-grained soil, and a shape function g(b) on π-plane was introduced.…”