Researchers tested the strength of saturated undisturbed Q_2 loess in a deep-buried tunnel using a triaxial shear test. They found that the loess softened under stress, showing brittle failure. The softening decreased with higher pressure, and the strain before failure was mostly elastic. Pore-water pressure increased with strain, especially under higher pressure. The loess became stronger with higher pressure, and the effective stress path followed a linear shape.