development of a concentric-membrane cell for true triaxial stress testing of cylindrical rock samples

Rocks in nature are typically subjected to triaxial compressive stresses, clearly underscoring the importance of reliably measuring their true triaxial strength. however, true triaxial loading testing of rocks, mainly performed on cubic samples, still faces many challenges, such as an intricate sample preparation process and costly setup. this study presents a cell designed to apply true triaxial loads to rock cores using the conventional compression testing apparatus. the use of cylindrical specimens simplifies sample preparation, ensures compatibility with existing core drilling methods, and allows for more efficient replication of in-situ stress conditions in rock formations while avoiding stress concentration issues commonly observed at the corners of cubic specimens. the design of the cell is based on two concentric membranes. the annulus space between the membranes is divided into four 90-degree sectors, three of which are filled with steel plates, while the fourth is filled with hydraulic fluid. each principal radial stress is provided by a separate hydraulic pump, and the axial stress is applied by a hydraulic jack. this study reports the results of 15 true triaxial tests on similar concrete samples using the innovative cell and under different stress fields.

development of a concentric-membrane cell for true triaxial stress testing of cylindrical rock samples

rocks in nature are typically subjected to triaxial compressive stresses, clearly underscoring the importance of reliably measuring their true triaxial strength. however, true triaxial loading testing of rocks, mainly performed on cubic samples, still faces many challenges, such as an intricate sample preparation process and costly setup. this study presents a cell designed to apply true triaxial loads to rock cores using the conventional compression testing apparatus. the use of cylindrical specimens simplifies sample preparation, ensures compatibility with existing core drilling methods, and allows for more efficient replication of in-situ stress conditions in rock formations while avoiding stress concentration issues commonly observed at the corners of cubic specimens. the design of the cell is based on two concentric membranes. the annulus space between the membranes is divided into four 90-degree sectors, three of which are filled with steel plates, while the fourth is filled with hydraulic fluid. each principal radial stress is provided by a separate hydraulic pump, and the axial stress is applied by a hydraulic jack. this study reports the results of 15 true triaxial tests on similar concrete samples using the innovative cell and under different stress fields.