Quick shear testTuesday, September 27, 2011 13:24
Quick shear test or Un-consolidated Un-drained test
In quick shear test, when the testing proceeds to failure so no drainage is allowed.
In this test no time is allowed to the soil sample to consolidate either before or during the test because the soil sample is sheared immediately after application of normal load.
During the testing the void ratio of the soil sample should change as little as possible is assured. The whole test is complete with in the duration of 5 to 10 minutes. The shearing force is applied rapidly during the test. Mostly pore pressure is not measured in this test. In real the test is in fact a total stress test and it yield the parameters of the total stress shear but still it is possible to measure pore pressure in Unconsolidated-undrained test (UU test).
Usually in practice we do not have excess time to dissipate excess pore pressure, we have to deal with quick shear loading, and there is no time to adjust the pressure.
The unconsolidated un-drained test is carried out by placing the sample in the chamber and introducing the confined pressure. The pressure is applied without allowing the sample to consolidate. The axial load is then applied without allowing drainage of the sample. The UU test can be run rather quickly as the sample is not required to consolidate. The sample is also not allowed to drain during application of the axial load. Because of less time required to run this test, it is often referred to as Q, test or quick shear test.