Laboratory study reveals near-surface pore collapse and tensile strain localization in drying loess soil, indicating that physical crusting is an active structural degradation process.
Key Points
To quantify the pore-scale structural and mechanical evolution of rainfall-induced physical crusting in loess soil during drying.
Subjected loess soil cores to varying antecedent rainfall durations alongside untreated control (CK) cores.
Tracked 3D pore architecture and internal strain across depth strata (0–3 mm surface shell vs. 3–10 mm subsurface band) using time-resolved X-ray computed tomography (XCT) and digital volume correlation (DVC).
Within the 0–3 mm shell, rainfall-treated cores showed mean total porosity reductions of approximately 24% at 0 h and 46% at the final dry state compared to CK.
Pore-network coordination numbers in the crust shell were approximately 24% lower through 108 h and 32% lower at the final dry state relative to CK.
Mean first principal strain localized in the 0–2.4 mm surface band at 0.025 compared to 0.002 in the 3.6–9.6 mm band and 0.004 in CK cores, with every rainfall-treated near-surface core exceeding CK values.