Development and Application of Triaxial Apparatus for Soil with High Bearing Pressure by Computed Tomography

ABSTRACT In order to study the macro and micro-mechanical properties of a soil sample under high pressure, we improved the traditional triaxial apparatus with high-bearing pressure for soil by combining it with the computed tomography (CT) system. The new apparatus overcomes the existing limits of low bearing pressure in the traditional triaxial apparatus and the small sample size in the micro-CT triaxial apparatus, keeping all the functions of the traditional triaxial apparatus. It can attain dynamic, quantitative, and noninvasive scanning of the internal structure of soil samples during the testing process. Moreover, the pressure chamber is made of high-strength and lightweight aircraft aluminum materials, allowing high X-ray penetration while ensuring that the scanned image is clear under high pressure. Consolidated undrained and drained triaxial tests are conducted by the apparatus on coral sand. The results show that the stress–strain curve is reasonable, the CT image is clear, and the particle breakage in the real-time loading process can be analyzed through image processing in single grading. As a result, the apparatus can be used to study the micro-mechanism of the internal structure of soil aiming at explaining its macro-mechanical behavior.