How to perform Vane shear test to test Strength of Soil at the Site?

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What is a shear vane test?

Vane Shear test is the process of calculating the undrained strength of fully saturated soil or clays without any disturbance. This method is very quick and easy to perform. So, this method is mostly preferred to calculate the shear strength of the soil. It can be done at the site or in the laboratory.

It is used basically in soft soil. In hard soil it is difficult to apply torque by the machine rod to get exact value of strength of soil.

Objective of Vane shear Test

To calculate and find the strength of soil sample of any site.

Vane shear test equipment

How to perform Vane shear test to test the Strength of Soil at the Site?
  1. Vane share apparatus
  2. Vane shear Machine

Vane shear test method and Procedures

1) At first clean the all apparatus used in the test nicely and apply the lubricant or grease to the lead screw.

2) Now, the sampling mould should be filled by remoulded soil at the required density and moisture content and take out extra soil samples from the mould by leveling it.

3) Mount the sampling tube with the sample under the base of the unit and clamp it in position.

4) Bring the maximum pointer into contact with the strain indicating pointer. Note down the initial reading of these pointers on the circular graduated scale.

5) Lower the bracket until the shear vanes go into the soil sample to their full length.

6) Operate the torque applicator handle until the specimen fails, which is indicated by the
return of the strain-indicating pointer or rotation of the drum.

7) Note down the readings of the maximum pointer.

8) The difference between initial and final reading will gives the angle of torque.

9) Repeat steps 3 to 6 times, on a number of test specimens to obtain the average shear strength of the soil sample.

Watch Video for full procedure

Observation Table

Calculation

I hope this article on “Vane shear test” remains helpful for you.

Happy Learning – Civil Concept

Contributed by,

Civil Engineer – Ranjeet Sahani

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