Understanding anisotropic mechanical properties of shales at different length scales: In situ micropillar compression combined with finite element calculations

From microstructural observations and experimental work it is known that shales consist of a mechanically weak porous fine‐grained clay matrix with embedded and mechanically strong silt/sand grains. Thereby, the respective contents of weak and strong constituents control bulk mechanical properties. In addition, the clay matrix is characterized by a preferred orientation of clay platelets, which are a major control on the bulk anisotropy of...