Theoretical Assessment of Increased Tensile Strength of Fibrous Soil Undergoing Desiccation

Soil reinforcement with discrete fibers is a viable technique to reduce desiccation cracking in compacted clay soils. The reduction in cracking is attributed to an increase in the tensile strength of the fiber-soil composite. A theoretical model is developed to describe the mechanism of the increased tensile strength due to fiber inclusion of soil undergoing desiccation. The model includes a distinctive effective stress combination acting on the fiber strings due to the generated matric suction by desiccation. Model formulation makes use of Mohr-Coulomb failure criterion at the interface area between fibers and the surrounding soil. The desiccation process of the soil generates matric suction within the soil mass, under given stress condition. The basic elements used in the model formulation include soil-water characteristic curve, Mohr-Coulomb parameters, and unsaturated soil parameters. Fiber inclusion increases significantly the tensile strength of the fiber-soil composite. This increase in tensile strength is expressed as a function of fiber content and soil-water content in this paper. Comparisons are made to published data regarding changes in tensile strength with variable water content.