It has been observed that a trench wall embedded in the soil of the Dead Sea has lost strength and is deteriorating due to brine attack. This phenomenon demonstrates that concrete wall structural stability and durability can be seriously endangered. Yet conventional analysis using macroscopic models is considered an oversimplification, as it neglects the existing micro-cracking and other nonlinearities that are endemic to such deterioration. The current study describes a multiscale formulation for estimating the anticipated reduction in strength of a concrete wall exposed to both external and internal briny water. Our methodology provides an upscale formulation to predict concrete response under aggressive environmental and partially confined conditions. The proposed method uses the concept of a “fictitious” water-to-cement (w/c) ratio to express the microstructural changes that cause an increase in material porosity, thus reflecting the material's degradation through leaching. Simulation results indicate that under the partially confined conditions representing actual ground pressure, the trench wall will remain stable for a service life of 40 years. Furthermore, the proposed model was experimentally calibrated and validated and found in agreement with experimental results.