The Triaxial test is the most common test to measure the solids, especially the rock and soil. The triaxial testing instruments manufacturer meets your specifications and designs your sample size and load capacity to help you in the process of testing.
If we apply some load on a clay saturated soil, because of that the water pressure is built up in the soil. So, just after the application of this tool, the pore water cannot move out of the soil and the condition will be undrained. But in other cases, if we are talking about after a long time application of this load, the pore water would have gone out and the condition would be drained. The conditions of drained and undrained are simulated in the lab in the form of different triaxial test. So we know the triaxial test is conducted in two stages i.e.
(a) First is the application of cell pressure and,
(b) Second is the application of additional deviator stress
- In the first stage, when we apply the cell pressure because of that equal amount of pore water pressure build-up in the soil. Now, there can be two things-
(a) We can keep the drainage line open or
(b) We can close the drainage line
If the drainage line is open then the soil will be consolidated and the volume change will happen which means the volume will decrease. If the drainage line is closed, the soil will be unconsolidated because no consolidation can take place unless the water moves out and the volume change will also not happen i.e. no volume change.
- In the second stage, we stimulate the actual application of the load that means when we apply the deviator stress, so because of that, the sheer stress builds up in the soil.
Thus, if the drainage line is open so the condition will be drained and if the drainage line is closed so the condition will be undrained.
Depending on the conditions there will be three types of trial tests-
- Unconsolidated undrained (UU) – If in the first stage the drainage line is closed, the soil will be unconsolidated, and in the second stage if the drainage line is closed,then the soil will be undrained. So this test is known as an unconsolidated-undrained test or UU test.
- Consolidated undrained (CU) – If in the first stage we keep the drainage line as open so the condition will be consolidated, the soil will be consolidated in the second stage if we keep the drainage line flows so the soil will be in undrained condition. Hence, this test is known as aCU test or aconsolidated undrained test.
- Consolidated drained (CD) – In the third test, we keep the drainage line open in the first stage as well as in the second stage. The condition here is consolidated and drained, and this test is called aconsolidated drained test.
Thus, these were the three important tests used in measuring the soil and other granular materials. Also, the triaxial testing equipment suppliers provide you the wide options, mainly located in Asia.