Microstructural and mechanical effects of strong fine-grained muscovite in soft halite matrix: Shear strain localization in torsion

摘要: [1] Torsion experiments were performed on polymer jacketed samples of 80% halite + 20% fine mica at 373, 473, and 573 K; a confining pressure 250 MPa; shear strain rate 3 × 10−4 s−1. The strength the aggregate depended temperature, rate, distribution produced by cold pressing, orientation emerging during experiments. Comparison with synthetic aggregates pure shows that halite-mica mixtures stronger in all cases. From stepping tests, we deduced stress exponents 12 10 373 473 K, respectively, contrast to values approximately 4 for same temperatures. Strain localized only except one run high-strain bands formed parallel applied plane K. We infer between increased temperature promoted localization, which occurred where local content was low, while unstrained domains persisted locally high strong framework. Mica reorientation softening K strain, from deduce alignment softening. conclude small amounts mineral phase can significantly increase dependence rock heterogeneous connectivity grains trigger localization.