Speaker
Description
Triaxial compression tests are commonly used to characterise strength and deformation behaviour of rock to get parameters for engineering design and modelling. For classic triaxial tests, samples are usually selected that they can be considered intact, in order to determine parameters of the intact rock. However, large-scale tests enable the investigation of inhomogeneous samples, which may also be interspersed with joints and can therefore be considered as representative samples of the rock mass. For this study a sedimentary slaking rock mass was examined. The rock mass were formed by sediment deposition in a sea and consists of layers of different materials, on the one hand silty mud stone layers and on the other hand layers of sand with varying degrees of cementation, some of these are also water-bearing. The triaxial compression tests were carried out with a sample height of 120 cm and a diameter of 60 cm. These dimensions make it possible to better replicate in situ conditions. To derive more information from one sample, multi-stage testing is an often carried out technique in classic triaxial tests. In this process, several stress states can be achieved with a single sample at different radial pressures. This type of test is even more cost-effective for large samples, as obtaining large samples involves a significant amount of effort. The results show that the greatest axial and lateral deformations occurred in the softer layers and along the pre existing joints. However, deformations also caused adjacent harder layers to deform laterally. Due to the heterogeneity of the sample, various failure mechanisms could be observed. On the one hand, shear failure occurred both within a layer and at the layer boundaries, on the other hand, axial splitting of the material also occurred.