Preloaded and premoistened foundation that overlaps sabkha collapse treatment with construction evaluated by coupled infiltration and consolidation analysis

Conventional improvement methods applied to sabkha soil (collapse soil) are time-consuming, lengthening the project schedule. This paper presents a novel preliminary concept for a pre-loaded, pre-moistened shallow foundation engineered construction. A single-footing cast directly on dry sabkha incorporates a 3 × 3 array of vertical holes through which distilled water is introduced, advancing as a Green-Ampt wetting front and dissolving the evaporitic bonds before superstructure load application. The improvement phase overlaps temporally with foundation construction, thereby removing the improvement task from the critical path, as per the schedule overlap principle. A coupled boundary-value problem (Terzaghi consolidation) and a transient infiltration problem are developed to model consolidation and collapse settlement due to wetting, and they are verified against a plane-strain elastic stress analysis and a one-dimensional coupled hydro-mechanical Richards-BBM model. Results show that the innovative foundation mobilizes approximately 434 mm of collapse settlement within 12 days (reaching 509.6 mm total settlement including elastic deformation), accounting for close to 90% of the layer's 480 mm theoretical collapse potential (CP. H). Analytical (477 mm) and numerical BBM-LC (456 mm) models confirm near-complete collapse mobilization to superstructure placement. The schedule overlap reduces the pre-superstructure phase by 62% compared with traditional pre-wetting. This saving depends on the in-situ hydraulic conductivity. At 0.70 m sleeve spacing, the probability of completing wetting-collapse within the 14-day window is 0.62, so site-specific k v measurement and a pilot infiltration test are required.