Effective stress in soil is the part of total stress carried by the soil skeleton. For saturated soil, Terzaghi’s relationship is σ’ = σ – u, where σ is total normal stress and u is pore-water pressure. Effective stress controls much of a soil’s shear strength, compression, and settlement behavior. The equation is short, but … Read more
The Boussinesq equation estimates the increase in vertical stress at depth caused by a point load applied at the surface of an ideal elastic half-space. For a vertical point load Q, the stress increase at radial distance r and depth z is: Δσz = (3Q/2π) × z³/(r² + z²)5/2 The result is a stress increment … Read more
Atterberg limits are water-content boundaries used to describe the consistency of fine-grained soil. The liquid limit (LL) separates plastic and liquid behavior, the plastic limit (PL) separates semisolid and plastic behavior, and the shrinkage limit (SL) marks the point below which further drying produces little additional volume reduction. The plasticity index is PI = LL … Read more
