Fully automatic three-axis compression instrumentThe experimental process mainly includes steps such as test preparation, sample installation, application of confining pressure, application of axial pressure, data acquisition and processing, and completion and cleaning of the test.

　　Fully automatic three-axis compression instrumentDetailed introduction:

1、 Preparation for the experiment

Sample preparation: Cut the undisturbed soil or manually prepare the soil sample according to the test procedure, put the latex film on the membrane bucket, evacuate the air, put the membrane bucket on the soil sample, and take out the soil sample together with the latex film.

Instrument preheating and initialization: Connect the power and gas source, preheat various sensors for 10 minutes, put them in the initial state, and initialize the control system data.

Exhaust and sealing: Using a back pressure system, the air in the pressure chamber soil sample seat and soil sample cap is discharged, and then the sample is installed. The soil sample seat and soil sample cap are tightly tied with rubber bands or latex film to ensure no air or water leakage.

Install pressure chamber: Install the three-axis pressure chamber, align the pressure transmission piston with the center of the soil sample cap, and tighten the pressure chamber sealing bolt. Adjust the crossbeam or lifting platform, fine tune the top adjustment screw of the piston rod, and make the axial pressure sensor slightly contact the top of the pressure transmitting piston rod.

Water injection and exhaust: Turn on the exhaust switch at the top of the pressure chamber, fill it with water, and then turn off the exhaust switch.

2、 Sample installation

Turn off the drainage switch: Before the experiment, turn off the upper and lower drainage switches.

Select test type: According to the test requirements, choose to conduct UU test (unconsolidated undrained shear test), CU test (consolidated undrained shear test), CD test (consolidated drained shear test) or reverse pressure saturation step.

3、 Apply confining pressure

Set confining pressure: According to the test requirements, set the required confining pressure value on the control panel.

Apply confining pressure: Open the confining pressure system, apply confining pressure to the sample, and maintain a constant confining pressure.

4、 Apply axial pressure

Determine shear rate: Determine the shear rate according to the experimental requirements.

Activate the vertical loading system: Activate the vertical loading system to apply axial pressure to the specimen, causing it to undergo axial deformation under constant confining pressure until it is destroyed.

5、 Data collection and processing

Automatic data collection: Based on different experimental requirements, the sampling method is determined and automatically collected by computer settings. The software interface should be able to reflect real-time experimental data and 'stress-strain' curves, as well as' pore pressure strain 'tracking curves.

Data upload and processing: Automatically stop the machine according to experimental needs or when the strain reaches 20%, and upload the data to the computer. After completing 3-4 sets of experiments, draw the Mohr envelope.

Analysis of test results: Based on the test data, calculate the strength indicators of the soil sample, such as shear strength parameters (cohesion and internal friction angle).

6、 End of experiment and cleaning

Turn off the instrument: After the experiment is completed, turn off the water, electricity, and gas sources of the instrument.

Take out the sample: Take out the soil sample and clean the container.

Fill in the usage record: Register the instrument usage record for subsequent management and maintenance.