Foundation Engineering Lecture 7 Settlement of Shallow Foundations • he settlement of a shallow foundation can be divided into two major categories: (a) elastic, or immediate, settlement Occurs immediately after the construction of the structure. in all soil types . (b) consolidation settlement. Consolidation settlement occurs over time. Pore water is extruded from the void spaces of saturated clayey soils submerged in water Elastic Settlement of Shallow Foundation on Saturated Clay In case of saturated clay the loading condition is undrained and hence , no volume change will occur during straining . Therefore the Poisson's ratio can be assumed μ=0.5 . The deformation can be calculated according to the theory of elasticity Elastic Settlement in Granular Soil Settlement Based on the Theory of Elasticity • The elastic settlement of a shallow foundation can be estimated by using the theory of elasticity. From Hooke’s law, Tolerable Settlement of Buildings In most instances of construction, the subsoil is not homogeneous and the load carried by various shallow foundations of a given structure can vary widely. As a result, it is reasonable to expect varying degrees of settlement in different parts of a given building. Uniform Settlement When the building settles uniformly so every point exhibit the same magnitude of deformation. The major effects due to settlement are, Unevenness in floor, etc. The settlement will also break the telephone, sanitary and the electric lines. Differential settlement When part of the structure is exhibit movement more than other part, This type of settlement is very serious and can lead to damage of the superstructure. Such as, Improper fit and function for doors and windows. Cracks and deterioration of foundations and slabs. Damage to walls and to flooring. Structural instability that could result in your building being deemed unfit for occupation or habitation Hence, it is important to define certain parameters that quantify differential settlement and to develop limiting values for those parameters in order that the resulting structures be safe.
