Development and Application of a Large-Scale Static and Dynamic True Triaxial Apparatus for Gravel

Abstract

To investigate the mechanical characteristics of gravel under general stress conditions, a large-scale static and dynamic true triaxial apparatus was developed at Tsinghua University. The largest specimen was 2 × 2 × 4 mm, and the applied pressure can meet the research requirements of large-scale geotechnical structures. A set of verification experiments with cyclic loadings of different directions and frequencies was performed to verify the accuracy of the loading system. Then, a static true triaxial experiment with constant mean principal stress, p, and generalized shear stress, q, was carried out to study the deformation characteristics of gravel under changing Lode’s angle, θ. The results show that changing Lode’s angle, θ, causes plastic deformations in all principal stress directions. In addition, a series of experiments with both axial and lateral cyclic loadings was carried out to study the deformation characteristics of a gravel specimen under different lateral dynamic conditions. Results from the experiments indicate that lateral dynamic loads significantly change the residual and reversible strains in all three principal directions.