Category: consolidation
The consolidation data is used for the following purpose:
1. Safe engineering design of structures.
2. Forecasting of the probable settlement of a structure.
3. Solving of various problems connected with the settlement of structures due to consolidation.
The theoretical concept of consolidation process was developed by Terzaghi. In order to compute the amount of consolidation( or settlement) after any given time t, Terzaghi derived the following basic equation is a free surface. δu/δt = cv (δu/δz) Where, cv = Coefficient of consolidation.
The above differential equation of consolidation describes the distribution of the hydrostatic excess pressure(u) with time(t) along with depth(z).
In the development of the Terzaghi theory of consolidation, the following 9 assumptions are made:
1. The soil is fully saturated.
2. The soil is homogeneous.
3. The time lag consolidation is entirely due to the low permeability of the soil.
4. Soil particles and water are incompressible.
5. Darcy’s law is strictly valid.
6. Coefficient of permeability is constant during consolidation.
7. The soil is restrained against lateral deformation.
8. Excess pore water drains out only in the vertical direction.
9. The boundary is a free surface.
Read Also:
Assumption of Bernoulli’s Theorem
Consolidation Settlement Analysis – Soil
What is Coefficient of Consolidation, Compressibility & Volume change With Their Equation
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| Consolidation Settlement (Settlement Analysis) |
Now, at an initial condition, void ratio(e0) = Vv/Vs Or Vv= e0.Vs
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The term coefficient of consolidation([latex] C_{v} [/latex]) is used to indicate the combined effects of the permeability and compressibility of soil on the rate of volume change.
It is the ratio of the coefficient of permeability(K) to the product of the coefficient of volume compressibility([latex] m_{v} [/latex]) and unit weight of water( [latex] \gamma _{w} [/latex]).
The unit of coefficient of consolidation( [latex] C_{v} [/latex] ) is cm²/Sec.
Coefficient of Compressibility is defined as the decrease in void ratio per unit increase in pressure.
It is a measure of compression of the soil mass. The unit of Coefficient of Compressibility([latex] a_{v} [/latex]) is cm²/gm.
The term coefficient of volume change or the coefficient of volume compressibility([latex] m_{v} [/latex]) is defined as the change in volume of a soil mass per unit of initial volume due to an increase in pressure.
where [latex] e_{0} [/latex] is the initial void ratio.
Read Also:
What is Degree Of Compaction, Optimum Moisture Content & Compacting Effort -Soil
What is Porosity, Void Ratio, Water or Moisture Content, And Degree of Saturation of Soil
Define Specific Gravity, Bulk Specific Gravity, Air Content and Percentage Air Voids-Soil
Consolidation can be defined as the compression resulting from a long-term static load and the consequent escape of pore water from the saturated soil mass.
According to Terzaghi, every process involving a decrease in the water content of a saturated soil mass due to the replacement of water by air is called a consolidation process.
Consolidation occurs due to one or more of the following factors:
a) Due to external static loads from structures.
b) Due to the self-weight of the soil such as recently placed fills.
c) Due to the lowering of the groundwater table.
d) Due to desiccation.
Read More:
Consolidation Settlement Analysis of Soil