Analysis of Deep Moisture Barriers in Expansive Soils. II: Water Flow Formulation and Implementation

Several alternatives have been proposed to prevent damage to civil infrastructure founded on expansive soils. For example, deep moisture barriers have been used in highways and buildings. However, in some cases, the protected lanes or structures degrade to similar levels as the unprotected ones, although at a smaller rate. In spite of these poor results, relatively few efforts have been devoted to the development of analytical methods for rational designs on expansive soils. This paper couples the constitutive model for expansive soils developed in the companion paper with flow equations in a deforming medium and a finite element code is developed. The resulting numerical tool has the capacity of computing soil suction and volumetric strain changes of expansive soils under a defined wetting–drying regime. To verify the capabilities of this computer code, a laboratory barrier model was built. The model was instrumented to measure soil suction changes and the corresponding surface displacements. The experimental and theoretical results were compared. Finally, the numerical model was applied to a design example of a deep moisture barrier.