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#### List of Standards

The list of standards (ASTM, BS and TCVN) which are commonly used in...

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Date Number of days off 2022  New Year's...

#### Standard Penetration Test

Standard penetration test (SPT) is one of the most common in situ testing...

#### Precision or Accuracy ???

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#### Bulk Density

1. Definition: A bulk density of a soil sample is defined as a mass per...

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• #### List of Standards

July 18, 2011
• #### Holiday calendar in 2022

October 2, 2011
• #### Standard Penetration Test

December 12, 2011
• #### Precision or Accuracy ???

January 7, 2012
• #### Bulk Density

February 20, 2012
• #### Compaction Test

March 7, 2012
• #### Warning on Webpage Content Stealing

February 27, 2014
• #### Datalogger for Oedometers

July 21, 2015

### Geotechnical Column

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"Symbols and definitions used in geotechnical engineering" is quoted from "Lexicon in 8 languages" (the fifth edition) published in 1981 by International Society for Soil Mechanics and Geotechnical Engineering.

3. Physical properties of soil

a) Density and Unit Weights

 Symbol Dimension Unit Measured quantity Description $$\rho_s$$ ML-3 kg/m³ Density of solid particles Ratio between mass and volume of solid particles $$\gamma_s$$ ML-2T-2 kN/m³ Unit weight of solid particles Ratio between weight and volume of solid particles $$\rho_w$$ ML-3 kg/m³ Density of water $$\gamma_s$$ ML-2T-2 kN/m³ Unit weight of water $$\rho$$ ML-3 kg/m³ Density of soil Ratio between total mass and total volume of soil $$\gamma$$ ML-2T-2 kN/m³ Unit weight of soil Ratio between total weight and total volume of soil $$\rho_d$$ ML-3 kg/m³ Density of dry soil Ratio between mass of solid particles and total volume of soil $$\gamma_d$$ ML-2T-2 kN/m³ Unit weight of dry soil Ratio between weight of solid particles and total volume of soil $$\rho_{sat}$$ ML-3 kg/m³ Density of saturated soil Ratio between total mass and total volume of completely saturated soil $$\gamma_{sat}$$ ML-2T-2 kN/m³ Unit weight of saturated soil Ratio between total weight and total volume of completely saturated soil $$\rho^{_{´}}$$ ML-3 kg/m³ Density of submerged soil Difference between density of soil and density of water $$\gamma^{_{´}}$$ ML-2T-2 kN/m³ Unit weight of submerged soil Difference between unit weight of soil and unit weight of water e - 1 Void ratio Ratio between volume of voids and volume of solid particles n - 1, % Porosity Ratio between volume of voids and total volume of soil w - 1, % Water content Ratio between weight of pore water and weight of solid particles (expressed in percentage) $$S_r$$ - 1, % Degree of saturation Ratio between volume of pore water and volume of voids

b) Consistency

 Symbol Dimension Unit Measured quantity Description $$w_L$$ - % Liquid limit Water content of a remoulded soil at transition between liquid and plastic states (determined by a standard laboratory test) $$w_P$$ - % Plastic limit Water content of a remoulded soil at transition between plastic and semi-solid states (determined by a standard laboratory test) $$w_S$$ - % Shrinkage limit Maximum water content at which a reduction of water content will not cause a decrease in volume of the soil mass $$I_P$$ - % Plasticity index Difference between liquid and plastic limit $$I_L$$ - 1 Liquidity index $$\large I_L=\frac {\left(w-w_p\right)} {I_P}$$ $$I_C$$ - 1 Consistency index $$\large I_C=\frac {\left(w_L-w\right)} {I_P}$$ $$e_{max}$$ - 1 Void ratio in loosest state Maximum void ratio obtainable by a standard laboratory procedure $$e_{min}$$ - 1 Void ratio in densest state Minimum void ratio obtainable by a standard laboratory procedure $$I_D$$ - 1, % Density index $$\large I_D=\frac {\left(e_{max}-e\right)} {\left(e_{max}-e_{min}\right)}$$

c) Grain size

 Symbol Dimension Unit Measured quantity Description D, d L mm Grain diameter Grain size as determined by sieve analysis or wet mechanical analysis $$D_n,d_n$$ L mm n percent-diameter Diameter corresponding to n percent by weight of finer particles $$C_U$$ - 1 Uniformity coefficient $$\large C_U=\frac {D_{60}} {D_{10}}$$

d)  Hydraulic properties

 Symbol Dimension Unit Measured quantity Description h L m Hydraulic head or potential Sum of pressure height $$\large\left(u:\gamma_w\right)$$ and geometrical height ($$\large z\;$$) above a given reference level q L3T-1 m³/s Rate of discharge, flow Volume of water seeping through a given area per unit of time v LT-1 m/s Discharge velocity Rate of discharge per total unit area perpendicular to direction of flow i - 1 Hydraulic gradient Loss of hydraulic head per unit length in direction of flow k LT-1 m/s Coefficient of permeability(hydraulic conductivity) Ratio between discharge velocity and corresponding hydraulic gradient $$\large\left(v:i\right)$$ j M L-2T-2 kN/m³ Seepage force The force due to flow with which the seeping water acts upon the soil particles in a unit volume of soil$$\large\left(j=i\cdot\gamma_w\right)$$