Relative Density
About Relative Density
One of the most important soil aggregate properties is relative density.
The relative density of soil is used to describe the state of compactness of granular material and is generally qualitatively described as very loose, loose, medium dense, dense, and very dense.
It is defined as the ratio of difference of void ratios in its loosest and densest state:
\(D_r = (e_\text{max} – e_\text{current}/(e_\text{max} –e_\text{min}).\)
There are many theoretical correlations of relative density with N SPT number. The two most important ones are outlined below:
Method 1: Terzaghi and Peck, 1967 correlates relative density with the uncorrected N SPT number (field data).
Current tool interpolates for intermediate values of Dr (%).
| N value (blows/ft or 305 mm) |
Relative Density |
Dr(%) |
|---|---|---|
| 0 to 4 | very loose | 0 to 15 |
| 4 to 10 | loose | 15 to 35 |
| 10 to 30 | medium | 35 to 65 |
| 30 to 50 | dense | 65 to 85 |
| > 50 | very dense | 85 to 100 |
- Method 2: Skempton , 1986 correlates relative density with the corrected (N1)60 number.
\(D_r=\sqrt{\frac{(N_1)_\text{60}}{60}}\)
The constant number 60 depends on the average particle size D50 and can range from 55 for sine sand to 65 for coarse sand. This tool uses an average value of 60 throughout.
References
- Terzaghi, K. and Peck, R.B. (1967) Soil Mechanics in Engineering Practice. John Wiley & Sons, New York.
- T. W. Lambe and R. V. Whitman, 1969, Soil Mechanics. John Wiley & Sons, New York.
- Skempton, A. W., 1986, Standard Penetration Test Procedures and the Effects in Sands of Overburden Pressure, Relative Density, Particle Size, Ageing and Over Consolidation, Geotechnique
Activated ags files
| # | Project | Ags Name | Method | Actions |
|---|
| SN | Method | N SPT Value (N) | Relative Density of Sand/Silty Sand(Dr(%)) | Class |
|---|