Abstract: Laboratory test standards are widely using the geotechnical investigation for various engineering projects. However, some of the standard procedures need to be modified for soils under special conditions so that the tested parameters are reasonable. As examples, it is observed that, in the drained and consolidated triaxial (CD) test, the quantity of drainage from the different water weight is greater than the theoretical drainage quantity, this will result in the increase the testing error since a larger actual major effective stress at failure. It is suggested that, in the CD test, the consolidated drainage be calculated as the loss of soil mass subtracts the drainage during the shearing. The preconsolidation pressure of cohesive soils can be obtained from the onedimensional consolidation test to the enough high consolidation pressure. To obtain an accurate preconsolidation pressure of soil samples, higher consolidation pressure is required for stiff soil or soil sample from a great depth. Before applying the Casagrande method, the soil deformation at preconsolidation pressures greater than 3200 kPa can be estimated from the previous testing pressures. These modifications provide efficient ways of test soil properties.

Key words: Consolidated Drained Triaxial Tests, Preconsolidation Pressure, Discussions on Testing Standards