Automatic triaxial testing system

Mô tả sản phẩm

                                                            Automatic triaxial testing system

 

 

1. Description

The BTU-TTS series is a multi-functional geotechnical triaxial testing system used to determine the mechanical properties of soil under different stress paths and drainage conditions. The series includes multiple models, covering testing requirements from small specimens to large coarse-grained soil specimens. The system integrates axial load, cell pressure, back pressure, shear rate control, and data acquisition modules, supporting various standard triaxial test methods.

 

2. Test Standards

Although the table does not explicitly list standard numbers, based on general triaxial test specifications, the system meets the following domestic and international standards:

• ASTM D4767(Consolidated Undrained Triaxial Compression Test)

• ASTM D7181(Consolidated Drained Triaxial Compression Test)

• ASTM D2850(Unconsolidated Undrained Triaxial Test)

• BS 1377: Part 7(British Standard Triaxial Test)

• ISO 17892-8(Triaxial shear test of soil)

• SL 237-1999(Chinese Geotechnical Test Procedure), etc.

 

3. Specification

Model	Max. specimen size (mm)	Max. axial force (kN)	Shear rate range (mm/min)	Cell/Back pressure volume (ml)	Max. air pressure (MPa)
BTU-TTS-1F	Φ70 × H140	10	0.00001～9.99999	150 (cell) / 250 (back) @ 2MPa	2
BTU-TTS-3F	Φ101 × H200	30	0.00001～9.99999	150 (cell) / 250 (back) @ 2MPa	2
BTU-TTS-5F	Φ38 × H76& Φ50 × H100	50	0.00001～9.99999	150 (cell) / 250 (back) @ 2MPa	2
BTU-TTS-6F	Φ150 × H300	60	0.00001～9.99999	150 (cell) / 250 (back) @ 2MPa	2
BTU-TTS-10F	Φ150 (height not specified)	100	0.00001～10	3000 @ 3MPa	3
BTU-TTS-20F	estimated Φ200	200	0.00001～10	3000 @ 3MPa	3
BTU-TTS-100	Φ300 × H600	1000	0.00001～5.6	8000 @ 3MPa	3
BTU-TTS-200	Φ300 × H600	2000	0.00001～5.6	16000 @ 6MPa	6

 

4. Detail

• Controller: Independent controllers for cell pressure and back pressure, supporting high-precision pressure/volume control.

• Data acquisition module: Standard, for real-time recording of axial force, displacement, pore pressure, volume change.

• Software functions: Includes the following test modules:

◦ Back pressure saturation

◦ Isotropic/anisotropic consolidation

◦ Unconsolidated Undrained (U-U)

◦ Consolidated Undrained (C-U) with pore pressure measurement

◦ Consolidated Drained (C-D) with volume change measurement

◦ K₀ consolidation

◦ Stress path testing

◦ Rheological testing

◦ Sensor calibration

◦ Post-processing and data export

• Air pressure: Used to apply cell and back pressure; models provide 2/3/6 MPa levels.

 

5. Application

• Geotechnical site investigation: Determine shear strength parameters (c, φ) of foundation soils and subgrade soils.

• Dam material testing: Large models (100/200) suitable for triaxial tests on coarse-grained soils and rockfill.

• Slope stability analysis: Obtain stress-strain curves under different drainage conditions.

• Underground engineering: Simulate pore pressure response during excavation and loading.

• Research and teaching: Used for validation of soil constitutive models and stress path studies.

 

6. Advantages

• Wide load and size range: From 10 kN to 2000 kN, covering fine-grained to very large coarse-grained soils.

• Ultra-low shear control: Minimum 0.00001 mm/min, suitable for creep/rheological tests.

• High-precision volume measurement: Back pressure volume control up to 16000 ml, meeting large specimen drainage/volume change requirements.

• Fully automatic software control: Integrates multiple standard test procedures, reducing human error.

• Modular design: Flexible configuration of cell/back pressure and air pressure; easy sensor calibration.

 

7. Parameter (Summary)

Parameter	Range / Value
Specimen diameter	70 mm ~ 300 mm (or larger)
Max. axial force	10 kN ~ 2000 kN
Shear rate	0.00001 ~ 10 mm/min (depending on model)
Cell pressure	2 MPa / 3 MPa / 6 MPa
Cell volume	150 ml ~ 16000 ml
Back pressure volume	250 ml ~ 16000 ml
Control method	Computer automatic control + data acquisition
Test types	UU, CU, CD, K₀, stress path, rheology

 

 

8. What To Choose

Recommendations based on specimen type and test requirements:

Specimen type	Recommended model	Reason
Fine-grained soil (clay, silt) diameter ≤70mm	BTU-TTS-1F	10kN sufficient, high speed accuracy, suitable for UU/CU/CD
Sand, fine gravel diameter ≤101mm	BTU-TTS-3F	30kN, 3MPa cell pressure, meets routine triaxial needs
Medium gravel, coarse sand diameter ≤150mm	BTU-TTS-5F or 10F	60~100kN, cell pressure 3~6MPa, optional large back pressure volume
Coarse-grained soil, crushed stone diameter ≤200mm	BTU-TTS-20F	200kN, suitable for subgrade/dam materials
Very large coarse-grained soil, rockfill diameter ≤300mm	BTU-TTS-100	1000kN, high stiffness, for high-stress triaxial tests
Ultra-high stress (e.g., deep rock)	BTU-TTS-200	2000kN, confirm specimen size

Also consider: need for pore pressure measurement, volume change accuracy, stress path control capability, and on-site compressed air supply.

 

9. Process Flow

Below is a standardized procedure for a typical Consolidated Undrained (CU) test using the BTU-TTS series (most steps automatically controlled by software):

Step 1: Specimen preparation and installation

• Prepare remolded or undisturbed soil specimen according to the model’s specimen size (e.g., Φ70×H140 mm).

• Assemble porous stone, filter paper, rubber membrane around the specimen, and place on the triaxial cell base.

• Install pore pressure sensor and top drainage line, seal the cell.

Step 2: System filling and de-airing

• Open cell and back pressure controllers, fill lines and cell with de-aired water, remove air bubbles.

• Use software’s “line de-airing” function to ensure accurate volume change measurement.

Step 3: Back pressure saturation

• Select “Back Pressure Saturation” module in software.

• Set target back pressure (e.g., 300 kPa) and cell pressure (20~50 kPa above back pressure).

• Automatically apply stepped back pressure while monitoring pore pressure coefficient B (typically B≥0.95 indicates full saturation).

Step 4: Isotropic/Anisotropic consolidation

• Select “Consolidation” module in software.

• Set target cell pressure (or K₀ condition) and consolidation time/volume change stability criteria.

• System automatically records volume change and pore pressure dissipation, generates consolidation log.

Step 5: Shearing (undrained or drained)

• Select “Shearing” module, set shear rate (e.g., 0.05 mm/min).

• Start axial loading; system real-time records axial force, displacement, pore pressure (CU) or volume change (CD).

• Automatically detect peak or termination condition (e.g., strain reaches 20%).

Step 6: Test termination and data processing

• Software automatically stops loading, releases cell pressure, exports raw data (stress, strain, pore pressure, volume change).

• Post-processing module calculates shear strength parameters (c, φ), elastic modulus, failure strain, etc.

• Generate test report, export to Excel/PDF.

Step 7: Equipment cleaning and maintenance

• Drain cell water, remove specimen.

• Clean lines and porous stone; perform sensor zeroing check.

For other test types (U-U, CD, stress path, rheology), only the drainage conditions and control targets during saturation/consolidation/shearing stages change; the software provides built-in wizards accordingly.