TY  - JOUR
A1  - Schuster, Valerian
A1  - Rybacki, Erik
A1  - Bonnelye, Audrey
A1  - Herrmann, Johannes
A1  - Schleicher, Anja Maria
A1  - Dresen, Georg
T1  - Experimental deformation of opalinus clay at elevated temperature and pressure conditions
T2  - Rock mechanics and rock engineering
N2  - The mechanical behavior of the sandy facies of Opalinus Clay (OPA) was investigated in 42 triaxial tests performed on dry samples at unconsolidated, undrained conditions at confining pressures (p(c)) of 50-100 MPa, temperatures (T) between 25 and 200 degrees C and strain rates (epsilon) (over dot ) of 1 x-10(-3)-5 x-10(-6) -s(-1). Using a Paterson-type deformation apparatus, samples oriented at 0 degrees, 45 degrees and 90 degrees to bedding were deformed up to about 15% axial strain. Additionally, the influence of water content, drainage condition and pre-consolidation was investigated at fixed p(c)-T conditions, using dry and re-saturated samples. Deformed samples display brittle to semi-brittle deformation behavior, characterized by cataclastic flow in quartz-rich sandy layers and granular flow in phyllosilicate-rich layers. Samples loaded parallel to bedding are less compliant compared to the other loading directions. With the exception of samples deformed 45 degrees and 90 degrees to bedding at p(c) = 100 MPa, strain is localized in discrete shear zones. Compressive strength (sigma(max)) increases with increasing pc, resulting in an internal friction coefficient of approximate to 0.31 for samples deformed at 45 degrees and 90 degrees to bedding, and approximate to 0.44 for samples deformed parallel to bedding. In contrast, pre-consolidation, drainage condition, T and epsilon(over dot )do not significantly affect deformation behavior of dried samples. However, sigma(max) and Young's modulus (E) decrease substantially with increasing water saturation. Compared to the clay-rich shaly facies of OPA, sandy facies specimens display higher strength sigma(max) and Young's modulus E at similar deformation conditions. Strength and Young's modulus of samples deformed 90 degrees and 45 degrees to bedding are close to the iso-stress Reuss bound, suggesting a strong influence of weak clay-rich layers on the deformation behavior.
KW  - Clay rock
KW  - Sandy facies of Opalinus Clay
KW  - Triaxial deformation experiments
KW  - Microstructural deformation mechanisms
KW  - Pressure-temperature and strain rate-dependent mechanical behaviour
KW  - Anisotropy
Y1  - 2021
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/61655
SN  - 0723-2632
SN  - 1434-453X
VL  - 54
SP  - 4009
EP  - 4039
PB  - Springer
CY  - Wien
ER  -