Terzaghi's One Dimensional Consolidation Theory - Civil Engineering (CE) MCQ

The theoretical concept of consolidation process was developed by in 1923. Skempton is known for Skempton’s A & B pore water pressure coefficients and also the bearing capacity of foundations.

In Terzaghi’s Theory of one dimensional consolidation, deformation of the soil is entirely due to change in volume. The change in volume can occur due to the decrease in the voids ratio or the effective height of the solids.

In Terzaghi’s Theory of one dimensional consolidation, Darcy’s law is perfectly valid. For ease in calculation, the flow of water in the soil is considered to be a laminar flow, thus validating the Darcy’s law.

At the time t₀, the whole of the consolidation pressure is carried by the pore water so that the initial excess hydrostatic pressure  equal to ∆σ. Hence, at initial time t₀, . This is represented by the line CD.

At intermediate time t, the consolidating pressure is partly carried by soil and partly by the pore water so that the consolidating pressure ∆σ at time t is given by, 

In general, the isochrone is the line on a diagram connecting points relating to the same time or equal times. So, in soil mechanics, the isochrones represent the water levels in piezometric tubes at the same time.

The hydraulic gradient is the driving force that causes groundwater to move in the direction of maximum decreasing total head. The hydraulic gradient is the change in total head divided the distance over which the change occurs.

Soils, by nature, are non-homogeneous media, and anisotropic in general. This means that their properties vary within relatively short distances in the vertical and horizontal directions. For the simplicity in solving the equations the soil is considered to be homogenous.

In Terzaghi’s Theory of one dimensional consolidation, soil particles and water is considered to be incompressible. Water is slightly compressible. We often treat it as incompressible when doing fluid flow calculations because the pressure changes involved are too small to make an appreciable change to the density.

In Terzaghi’s Theory of one dimensional consolidation, coefficient of permeability is constant during the consolidation. This assumption is made so that not more than one coefficient of permeability is used in the same problem.