Deformation Properties of Red River Sand in Cyclic Triaxial Tests: Fid-Bau Portal

Deformation Properties of Red River Sand in Cyclic Triaxial Tests

Nguyen, Nam Hong / Van Pham, Manh

Small strain deformation properties of dry, medium dense and dense Red river sand such as Young’s modulus, E_z and damping ratios, h, were experimentally investigated by using cylindrical specimens (D_i = 5 cm, Hi = 10 cm) during isotropic consolidation with confining stress, $σ_{c}^{'}$ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma_{c}^{\prime }$$\end{document}, from 30 to 400 kPa and came back. At some stable stress states, E_z was measured with the non-contact transducer, by applying a series of unload-reload cycles with vertical strain single amplitude, $ε_{a} \leq 0.001 %$ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon_{a} \le 0.001\%$$\end{document}. In addition, the dependency of E_z and h with $ε_{a}$ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon_{a}$$\end{document} was investigated by applying a series of cyclic loading with changing the $ε_{a}$ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon_{a}$$\end{document} amplitude from 0.001 to 0.04%, at constant $σ_{c}^{'} = 100 kPa$ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma_{c}^{\prime } = 100\;{\text{kPa}}$$\end{document}. Test results show that the E_z could be simulated as a power function of $σ_{c}^{' m}$ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma_{c}^{\prime m}$$\end{document} with an average power value m = 0.52 during isotropic consolidation. In addition, the degradation of the vertical Young’s modulus and the increase of damping ratio on the single vertical strain amplitude at given confining stress were observed. The experimental results were consistent with the published data.