triaxial compression apparatusIt is a key testing equipment used to determine the shear strength of soil or rock, widely used in fields such as geotechnical engineering, geological exploration, and foundation research. It is to determine the shear strength of soil or rock by simulating its stress state in three dimensions. During the experiment, the soil or rock sample is made into a cylindrical specimen, covered with a rubber membrane, and placed in a closed pressure chamber. Inject air pressure or hydraulic pressure into the pressure chamber to subject the specimen to the surrounding pressure and maintain this pressure constant throughout the entire testing process. Then, vertical pressure is applied to the specimen through an axial loading system until the specimen is damaged due to shear. Based on the stress data measured in the experiment, the strength index of the soil sample can be organized and calculated.
triaxial compression apparatusIt mainly consists of the following parts:
Pressure chamber: a closed container composed of a metal cover, base, and transparent organic glass cylinder, used to withstand and transmit pressure.
Axial loading system: used to apply vertical pressure to the specimen, usually using strain controlled or stress controlled methods.
Voltage stabilization and regulation system: used to control and regulate the pressure inside the pressure chamber, ensuring the stability of the pressure during the testing process.
Measurement system: including pressure sensors, displacement sensors, etc., used to measure pressure and displacement changes during the testing process.
According to the different drainage conditions during the experiment, triaxial compression testing can be divided into the following three methods:
Unconsolidated undrained shear test (UU test): The specimen is not allowed to drain during the entire test process of applying surrounding pressure and subsequently applying deviatoric stress until it is sheared. The actual engineering conditions corresponding to this experimental method are equivalent to the stress conditions during rapid loading in saturated soft clay.
Consolidation undrained shear test (CU test): When applying ambient pressure, allow the specimen to fully drain. After consolidation and stabilization, close the drainage valve, and then apply deviatoric stress to cause shear failure of the specimen under undrained conditions. This test method is applicable to the stress situation of normally consolidated soil layers under the action of a large and rapid live load or newly added load during the completion or use of the project.
Consolidation Drainage Shear (CD Test): Drainage is allowed throughout the entire test process, including the application of surrounding pressure and subsequent application of deviatoric stress until shear failure, and sufficient time is given for the pore water pressure in the specimen to dissipate.