This paper presents pore unit assembly-discrete element model (PUA-DEM), a pore-scale hydromechanical framework that resolves interactions between mobile granular particles and multiphase fluids in unsaturated granular media. The framework uniquely integrates DEM with pore-scale hydrodynamic models to capture unsaturated flow dynamics, while leveraging a two-way coupling mechanism to ensure bidirectional fluid-grain feedback through stabilized domain partitioning. Further innovations include a dynamic pore-merging and retriangulation algorithm that enhances computational efficiency for large-scale systems. Validated against experimental data for glass beads and Ottawa sand, PUA-DEM accurately reproduces critical hydromechanical phenomena-including capillary/viscous fingering, wetting-induced granular swelling/collapse, and quasi-static deformation-under diverse saturation and loading regimes. Numerical case studies reveal how capillary forces and wetting fluid saturation collectively govern granular response, from pore-scale meniscus evolution to macroscale flow instabilities. By bridging pore-and particle-scale physics, PUA-DEM advances predictive modeling of partially saturated granular systems, offering transformative insights for geohazard mitigation, sustainable agriculture, pharmaceutical manufacturing, and energy-related engineering applications.

In this research, the effect of using alpha fibres on the physico-mechanical properties of compressed earth bricks (CEBs) was investigated. CEBs were produced using soil, lime and different amounts (0%, 0.5%, 1%, 1.5% and 2%) of raw (RAF) or treated alpha fibres (TAF). First, the diameter, density and water absorption of RAF and TAF were determined. Then, the produced CEBs reinforced by these fibres were subjected to compressive strength, thermal test, density and capillarity water absorption tests. The obtained results showed that the addition of RAF and TAF leads to a reduction of the thermal conductivity by 33% and 31%, respectively. The finding also indicated that the density was decreased by 26% and 17% with the inclusion of TAF and RAF respectively. Besides, the compressive strength was reduced and water absorption coefficient was increased when fibres reinforced CEBs but remaining within the standard's recommended limits. Moreover, the addition of fibre improves the acoustic properties of samples by 98%. The CEBs developed in this paper could be an alternative to other more common building materials, which would lead to a reduction of energy demand and environmental problems.

Usually, the term 'rising damp' refers to capillary water rising from the ground which may damage architectural heritage. In this work, the essence of rising damp in extremely arid regions and its driving force are revealed based on experiments monitoring the relative humidity (RH) and atmospheric pressure (AP) in the Dunhuang Mogao Grottoes. The air in the vadose zone, the unsaturated region between ground level and the top of the water table, is here referred to as 'earth-air'. When the AP rises, the earth-air is compressed, and atmospheric air enters into the soil. Then, when the AP drops, moist earth-air expands and rises into the structure. The RH in the soil is thus negatively correlated with the AP, yielding a correlation coefficient of up to -0.94. Under the action of this long-term dry-wet alternation, the salt present in the building near ground undergoes repeated cycles of crystallization and dissolution, resulting in efflorescence and a deterioration zone. Therefore, the deterioration due to rising damp in extremely arid regions is caused by the rising of moist earth-air rather than capillarity. The height to which it rises is directly proportional to the amplitude of the daily AP fluctuation and thickness of the vadose zone, exhibiting a bimodal fluctuation pattern on a daily scale. The discovery of this mechanism of rising damp provides a scientific basis for preventive conservation interventions.

Suction stress, the part of effective stress induced by soil-water interaction, is the source for the intrinsic cohesion of fine-grained soil slurries. Here, the previous unified effective stress equation is generalized to extend the suction stress variation from the liquid state to the oven-dry state, yielding an augmented closed-form equation. This equation includes a new term, named slurry adsorptive suction stress, to incorporate the adsorptive mechanism of soil slurries at the liquid state. This adsorption mechanism involves the interparticle van der Waals attraction, face-to-edge attraction, and electrical double-layer repulsion when soils are in the liquid state. The proposed equation is validated with a wide array of 12 fine-grained soils' shrinkage curves, modulus, and suction stress data measured by the drying cake test. It is demonstrated that the proposed equation can excellently capture the experimental data across all saturations. Furthermore, the practical implications of the proposed model are illustrated via its relevance to rheological properties of soil slurries and correlations with both liquid limit and plastic limit. (c) 2024 American Society of Civil Engineers.