Recent Advances in Triaxial Facilities for Soil and Rock Testing


Pathegama Gamage Ranjith

Department of Civil Engineering, Monash University, Melbourne, Australia


Triaxial equipment is used to investigate properties of geological materials such as soil and rocks under different boundary conditions. There is a high demand for laboratory testing techniques for soil and rocks in geotechnical, mining and petroleum engineering. This study is a review of recent advances in developed triaxial facilities. Triaxial apparatus have been classified based on ground stress field and the presence of fluid phases within the specimen. In this paper, they are mainly classified as saturated and unsaturated apparatus. Many developed apparatus are suited for testing specimens under saturated conditions. Various techniques used in the past to measure diametric/circumferencial deformation and volume change of the specimen are in detail discussed. More significantly, development of two-phase high pressure triaxial apparatus for rocks and its test procedures are elaborated. Findings of this study suggest that conventional triaxial apparatus still dominate, particularly in rock mechanics to study multi fluid flow through rocks and its stress/strain behavior. The study also shows that clip gauges to measure diametric or circumferential deformations and volume change device based on the volume of fluid entering the cell to compensate the change in volume the sample are more accurate and easy to operate at elevated confining pressure for both soil and rocks. Further research and development is still necessary in unsaturated flow (i.e. multi fluid flow) equipment for rock as they are not so popular because of its complexity and tedious test procedures.

Keywords: Hollow, true and conventional triaxial apparatus, saturated, unsaturated, two-phase flow, permeability, deformation, volume change

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