## 5 Empirical Formula for Determination of the Coefficient of Permeability

The coefficient of **permeability of soil**(K) can also be computed from several empirical formulae, which are given below:

### 1. Jaky’s Formula

Jakey in 1944 found an empirical formula of ‘K’ for all soils; [latex] K = 100 D_{m}^{2} [/latex] , Where [latex] D_{m} [/latex] is grain size (in cm) that occurs with the greatest frequency.

### 2. Allen Hazen’s Formula

[latex] K = C D_{10}^{2} [/latex] , where C is a constant. The value of C is taken approximately equal to 100, when [latex] D_{10} [/latex] is expressed in cm.

### 3. Terzaghi’s Formula

Terzaghi (1955) developed the following formula for fairly uniform sands, which reflects the effects of grain size and void ratio.

[latex] K = 200 D_{e}^{2} . e^2 [/latex] , Where [latex] D_{e} [/latex] = Effective grain size.

### 4. Kozney’s Formula

[latex] K = \frac{1}{K_{k} \eta S_{s}^{2}} \times \frac{n^3}{1-n^3} [/latex] , where [latex] S_{s} [/latex] = Specific surface of particles, [latex] \eta [/latex] = Viscosity, and [latex] K_{k} [/latex] = Constant( that is equal to 5 for spherical particles).

### 5. Louden’s Formula

[latex] \Rightarrow log_{10} (KS_{s}^{2}) = a + bn [/latex]

Where a and b are constants, the value of which are 1.365 and 5.15 respectively for permeability at 10**°C**.

*Read Also:*

1. Capillarity Permeability Test

2. Coefficient of Permeability of Soil by Constant Head Permeameter