Subject: CE 441 Geotechnical Laboratory,
Topic: Hydraulic Conductivity: Constant and Fall Head Method
The constant head test use for gravel soils. Also, the fall head method use for mild soils. Two laboratory tests were allowed to define a permeability of the soil by calculating Darcy’s law and the coefficient.
Clean the chamber sections. After that, put the gasket inside the chamber then put the first one porous stone. Then put the sample of a dry soil and used a tamping to compact a layer of the soil. Put the gasket on top of lower chamber then put the other upper section of chamber. Be careful to level the top surface 2 cm of the soil and put the porous stone on top. Also, do not forget to put the spring on the top of porous stone. Tight the chamber, then record the length and width. After that, put the funnel on top to allow the constant water. From a tail of the funnel put the tube goes to the bottom of the outlet of the permeameter. Open a bottom outlet valve to record 5 second it takes to fill the graduated cylinder, and then record the temperature of water.
The values of coefficient on constant head test found 0.0147, 0.0159, and 0.0147 based on temperature 22 degree. Also, the average of constant head was 0.0151 cm/s. The average of the falling head test was found 0.00899 cm/s. When the viscosity of water goes down the coefficient and flow rate will be increased.
This experiment had defined the coefficient of permeability of a sample soil that had been given.
By using constant and fall head methods based on Darcy’s law equation. The soil defined to be fine sand.