Large-Scale True Triaxial Apparatus for Geophysical Studies in Fractured Rock

The study of fractured rock masses in the laboratory remains challenging because of the large specimen sizes and bulky loading systems that are required. This article presents the design, structural analysis, and operation of a compact and self-reacting true triaxial device for fractured rock. The frame subjects a 50 cm by 50 cm by 50 cm fractured rock specimen to a maximum stress of 3 MPa along three independent axes. Concurrent measurements include long-wavelength P-wave propagation, passive acoustic emission monitoring, deformations, and thermal measurements. The device can accommodate diverse research, from rock mass properties and geophysical fractured rock characterizations, to coupled hydro-chemo-thermo-mechanical processes, drilling, and grouting. Preliminary wave propagation data gathered under isotropic and anisotropic stress conditions for an assembly of 4,000 rock blocks demonstrate the system’s versatility and provide unprecedented information related to long-wavelength propagation in fractured rock under various stress anisotropies.

Garcia AV, Rached RM, Santamarina JC (2018) Large-Scale True Triaxial Apparatus for Geophysical Studies in Fractured Rock. Geotechnical Testing Journal 41: 20170144. Available:

Financial support for this research was provided by the KAUST endowment. The authors would like to thank Gabrielle Abelskamp for her assistance with editing this manuscript.

ASTM International

Geotechnical Testing Journal


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