Investigation of mechanical properties and acoustic emission of travertine: A case study in Jiuzhaigou, Southwestern China

The travertine is an ideal material for damage restoration in Jiuzhaigou, but its mechanical properties have not been well understood. In this study, the chemical composition and micro-structures of Jiuzhaigou travertine were analyzed using the X-ray diffraction (XRD) measure-ment, scanning electron microscope (SEM) imaging and energy-dispersive spectroscopy (EDS) quantitative analysis. The mechanical properties including failure mode, shear strength, cohesion and internal friction of Jiuzhaigou travertine were investigated through the triaxial compressive tests and acoustic emission (AE) measurements. A damage model considered both the elastic modulus and AE count and accumulation together was also established. The results show that, the travertine samples are primarily composed of calcite, with porous micro-structures and complex porosity system, which leading to poor integrity and weak cementation. Their failure mode is mainly single-sided shear failure, the increasing confining pressure significantly increases their steepness of axial deformation and peak strengths, and leads to a more concentrate and regular distribution of AE points in the travertine samples. The mechanical properties of travertine samples fall between the sandstone and clay, and are more similar to those of sandstone. The calculated stress-strain curves from the proposed model and the experimental data have a good agreement, and can serve as a valuable reference for future studies on the mechanical behavior of travertine.

Automated summary

By analyzing the chemical composition and micro-structures of Jiuzhaigou travertine, this study found that the travertine samples are primarily composed of calcite and have porous micro-structures. Their failure mode is mainly single-sided shear failure, and increasing confining pressure significantly increases their axial deformation and peak strengths. The mechanical properties of travertine samples fall between sandstone and clay, and the proposed model and experimental data have good agreement.