Soil Resistivity Testing Method – Driven Rod

The driven rod test is a geotechnical investigation method which determines the resistance of soil to the penetration of a rod or other penetrometer. 

The Soil resistivity is determined using different Soil Resistivity Testing methods. However the Driven Rod, described below is the last of the three most popular Soil Resistivity Testing methods we use to measure the soil resistivity.

To complete a driven rod test, you will need the following equipment:

  • A penetrometer (usually a rod or cone-shaped device)
  • A hammer or other tool for driving the penetrometer into the ground
  • A torque meter or other device for measuring the resistance of the soil

Process for conducting a driven rod test:

  1. Determine the desired depth of the probe. This will depend on the depth of soil you want to test and the characteristics of the penetrometer.
  2. Set up the penetrometer. The penetrometer should be placed on the ground at the desired location.
  3. Drive the penetrometer into the ground. The penetrometer should be driven to the desired depth using the hammer or other tool.
  4. Measure the resistance of the soil. The torque meter or other device should be used to measure the resistance of the soil as the penetrometer is being driven into the ground.
  5. Record the results. The resistance of the soil should be recorded at regular intervals as the penetrometer is being driven into the ground.
  6. Repeat the process at multiple locations to get a representative sample of the soil.
  7. Calculate the average resistance of the soil using the readings from each location.

Driven Rod Method

This method is also known as the three probe method or three pin method [3].

Soil Resistivity Testing Methods Driven Rod

This method is suited for areas where the physical layout makes the usage of the Wenner and Schlumberger methods difficult; the soil resistivity under this method can be calculated using equation 3:

Driven Rod Equation

Where:

l is the length of driven rod in contact with the earth

d driven rod diameter

Alternative Soil Resistivity Testing Methods:

Click here to find out how to avoid the common mistakes of Soil Resistivity Testing.

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Soil Resistivity

Soil Resistivity Testing – Common Mistakes

We take a look at soil resistivity and provide practical advice on what is ground soil resistivity, why we measure it and these common mistakes when Soil Resistivity Testing: