True‐Triaxial Drained Test of Tengger Desert Sand

Li, Xuefeng; Ma, Zhigang; Lu, Wennan; Wang, Yandong

doi:10.1155/2020/8851165

“…e air pressure controller is connected to the air collector and air pump, indicated by the green line in Figure 1. For more detailed introduction of the loading method, see reference [16].…”

Section: The True Triaxial Equipmentmentioning

confidence: 99%

“…However, there are relatively few results from triaxial tests of aeolian sand in China. For the true triaxial test of aeolian sand, only Li et al [16] carried out the drainage test of Tengger Desert sand. For the conventional triaxial test, Deng [17] and Song [18] had carried out static-dynamic tests.…”

Section: Introductionmentioning

confidence: 99%

The Undrained Characteristics of Tengger Desert Sand from True Triaxial Testing

Li

¹

,

Lu

²

,

Ma

³

et al. 2021

Advances in Civil Engineering

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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.

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“…A comprehensive constitutive model for sandy soils should be able to reflect stress-strain behaviors under all kinds of stress paths in the threedimensional stress space [3], including proportional or non-proportional loads and unloads. The stress-strain behaviors and non-coaxial response along the stress paths of radial shear have been investigated well by true triaxial tests [4][5][6][7][8][9][10][11][12] and hollow cylinder apparatus (HCA) tests [13][14][15][16][17]. However, complex shear stress paths, such as rotational shear [18] and mixed shear, have also attracted attention in connection with the deformation and strength behaviors of soils during earthquakes and wave loads [19].…”

Section: Introductionmentioning

confidence: 99%

The Non-coaxiality and Fabric Evolution of Granular Materials in Mixed Load and Unload on Deviatoric Plane

Li,

Li

2024

Preprint

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The non-coaxiality and fabric evolution of granular materials with the stress path of mixed load and unload on deviatoric plane have not been well understood, particularly for mixed unload. This study is to survey the combined influence of intermediate principal stress ratio b-value, stress ratio level, confining pressure, and inter-particle friction on the deformation, non-coaxiality by true triaxial simulations with DEM (discrete element method), in mixed loads and unloads, and their correlation to micro-fabric evolution. Differences in deformation, non-coaxiality, and fabric evolution results are analyzed. The non-coaxiality is closely related to stress increment direction, the current stress state, confining pressure\({\sigma _c}\), and inter-particle friction coefficient\(\mu\), with distinct non-coaxial response in mixed unloads. It further verifies that the magnitude and orientation evolution of contact fabric are responsible for the deformation and non-coaxial response in mixed load and unload.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

Cyclic True Triaxial Tests on Aeolian Sand Considering Initial Shear Effect

Xu

¹

,

Li

²

,

Lü

³

et al. 2022

Sustainability

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Under traffic loading, the soil elements in subgrade are subjected to a complex 3D stress path. To investigate the cyclic behavior of desert subgrade under initial shear stress conditions, the number of cyclic true triaxial tests were implemented on aeolian sand from the Tengger Desert. A large range of initial shear stress levels and different cyclic stress paths (various combinations of cyclic major and intermediate principal stresses) were designed in the experiments. The results show that the initial shear stress level significantly influences the cyclic response, and the response mode of aeolian sand under initial shear stress is incremental failure and elastic shakedown, while it is critical failure without initial shear stress. With the increase in initial shear stress, the permanent strain increases first and then decreases, with the maximum permanent strain occurring at q0 = 50 kPa. Moreover, by comparing the test data under different cyclic stress paths, it is found that the cyclic resistance decreases with the increase in the coefficient of cyclic intermediate principal stress bcyc. Compared to the limiting pore pressure criterion, the conventional 5% axial strain failure criterion may overestimate the cyclic resistance, leading to unsafe evaluation and design. Therefore, by using the pore pressure criterion, the relationship between the limit pore pressure ratio and the initial stress condition was investigated and it was found that the limit pore pressure ratio decreased linearly when the initial shear stress increased.

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True‐Triaxial Drained Test of Tengger Desert Sand

Cited by 9 publications

References 15 publications

The Undrained Characteristics of Tengger Desert Sand from True Triaxial Testing

The Undrained Characteristics of Tengger Desert Sand from True Triaxial Testing

The Non-coaxiality and Fabric Evolution of Granular Materials in Mixed Load and Unload on Deviatoric Plane

Cyclic True Triaxial Tests on Aeolian Sand Considering Initial Shear Effect

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