Maurice A. Biot's "General Theory of Three-Dimensional Consolidation" presents a mathematical framework for understanding soil settlement under load. The theory considers soil as an elastic porous medium with water filling the voids. It derives the necessary physical constants and equations to predict settlements and stresses in three-dimensional problems. The paper introduces the concept of operational calculus as a powerful tool for solving consolidation problems without needing to calculate stress or water pressure distributions inside the soil. The theory assumes isotropic, reversible, and linear stress-strain relationships, with small strains and incompressible water. It also accounts for the influence of initial stress and the presence of air bubbles. The paper establishes fundamental equations for consolidation, including the relationship between stress, water pressure, and strain. These equations are applied to a standard soil test, showing how the settlement of a soil column under load depends on time and the properties of the soil. The paper also discusses the simplified theory for completely saturated clay, where the initial compressibility is negligible compared to the final compressibility. In this case, the number of physical constants is reduced, and the equations simplify to describe the consolidation process. The theory is further applied to derive the settlement of a completely saturated clay column under a suddenly applied load using operational calculus, which provides a simplified and efficient method for solving consolidation problems. The results show that the settlement of a soil column under load follows a parabolic curve over time, with the final settlement determined by the final compressibility of the soil. The theory provides a comprehensive and general framework for understanding the consolidation of soils, which has been widely applied in geotechnical engineering.Maurice A. Biot's "General Theory of Three-Dimensional Consolidation" presents a mathematical framework for understanding soil settlement under load. The theory considers soil as an elastic porous medium with water filling the voids. It derives the necessary physical constants and equations to predict settlements and stresses in three-dimensional problems. The paper introduces the concept of operational calculus as a powerful tool for solving consolidation problems without needing to calculate stress or water pressure distributions inside the soil. The theory assumes isotropic, reversible, and linear stress-strain relationships, with small strains and incompressible water. It also accounts for the influence of initial stress and the presence of air bubbles. The paper establishes fundamental equations for consolidation, including the relationship between stress, water pressure, and strain. These equations are applied to a standard soil test, showing how the settlement of a soil column under load depends on time and the properties of the soil. The paper also discusses the simplified theory for completely saturated clay, where the initial compressibility is negligible compared to the final compressibility. In this case, the number of physical constants is reduced, and the equations simplify to describe the consolidation process. The theory is further applied to derive the settlement of a completely saturated clay column under a suddenly applied load using operational calculus, which provides a simplified and efficient method for solving consolidation problems. The results show that the settlement of a soil column under load follows a parabolic curve over time, with the final settlement determined by the final compressibility of the soil. The theory provides a comprehensive and general framework for understanding the consolidation of soils, which has been widely applied in geotechnical engineering.