Finite Element Analysis of Hollow Cylinder Test Considering Variation of Wall Thickness

Hollow cylinder torsional shear test is simulated regarded as a boundary value problem employing a three-dimensional static/dynamic soil-water coupled finite deformation analysis to investigate the influence of the specimen geometries on apparent behavior concerned in practical experiments. 1) A “Perfect path” which means the response of a single three-dimensional element with uniform deformation is calculated to investigate the effect of non-uniformities on the apparent behavior. As can be seen, only the apparent behavior with thinnest wall thickness coincides with the “Perfect path”, which indicates a uniform deformation inside the thinnest specimen; 2) It was found that when the cylinder wall thickness became smaller, the non-uniformity also decreased correspondingly, which can also be seen in the element behaviors of the thickest specimen; 3) Even thought the non-uniformity in different geometries is quite different, there seem to be no significant influence on the apparent behavior. The reason may lie in the extreme constraint conditions, namely displacement control.

Mechanical behavior of Tien-Liao mudstone in hollow cylinder tests

A series of hollow cylinder tests were conducted to study the stress–strain characteristics and the yield surface of Tein-Liao mudstone, a soft rock widely distributed in southwestern Taiwan. These tests were carried out under different stress paths designed to utilize the versatility of the hollow cylinder testing system. The test results were used to establish the yield surface of the mudstone in the principal stress space. The experimental results were used to examine the accuracy of existing yield criteria, such as the Coulomb criterion, the extended Hoek-Brown model, and the Kim-Lade model. Among the three yield criteria examined, the Kim-Lade model provided the best agreement with the experimental results, although both the extended Hoek-Brown model and the Kim-Lade model are adequate for modeling the yield surface of the mudstone.Key words: rock, yield surface, stress path, hollow cylinder test.