A Guide For Triaxial Shear Testing

triaxial shear test

The triaxial shear test is an experiment used to detect several soil characteristics like its strength, resilience, and durability. The soil is put under different types of pressure so that its strength can be tested. The shear test is also available in an upgraded version of the digital triaxial shear test. The test results appear digitally rather than to employ a person to write down the results on paper. The results are automatically downloaded in the computer software and can be presented in a graphic format. However, extensive care must be shown while using apparatus for testing. Only authorized personnel should use it under proper conditions and by wearing personal protective equipment to ensure maximum safety and prevention of danger.

Goals of testing

The triaxial shear test of soil aims to determine the bond of the soil and its ability to bear stress. This test is very diverse and more accurate in its results. Any type of soil can be used for this experimentation, along with controlling the water retention power.

Tools needed

  • Triaxial Shear Test Apparatus
  • Rubber ring
  • Open-ended cylindrical section

Sample requirement

Measurements of the sample must be as follows

  • Minimum diameter: 70mm
  • Largest particle in the sample: Smaller than 1/6th of the sample’s diameter
  • Height-Diameter ratio: Between 2 and 3, measured to the closest 0.3mm

The presence of oversized particles must be mentioned in the report. Cautiously handle the sample to reduce any disturbance in it or to lose its moisture. The sample should have a consistent circular cross-section. Measure the dimensions of the sample and then close it to the rubber membrane. Seal it to the sample base and cap.

Process of testing

  1. Put together the triaxial chamber and then place the sample inside it.
  2. Align the axial load valve with the sample cap by bringing them together again and again. But be careful when applying deviator pressure to the sample, which should not be more than 0.5% of the predicted compressive power.
  3. Lock the load piston above the sample cap if the weight of the valve is enough to put deviator stress to the sample more than 0.5% of the predicted compressive power. Keep it secure in the place until the pressure is applied.
  4. Keep the triaxial cell along with the axial loading apparatus. Align it with the axial load cell and the triaxial cells so as to avoid any side force on this piston while experimenting.
  5. Join the device that maintains and measures the pressure. Afterward, pour the triaxial cell with the fluid up to the given mark. The gadget that maintains and measures the pressure should be adjusted to the required pressure in the cells and the fluid.
  6. When the pressure is applied, measure the readings on the screen when the piston meets the sample cap.

This testing is used to know the durability of the cylindrical sample of the soil in a situation that has no disturbance, along with controlled pressure applied. The operators should follow the proper instructions to operate the apparatus for maximum safety.

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