Bishop Stress Path Triaxial Apparatus

Bishop Stress Path Triaxial

1. Description

This equipment is a Bishop Stress Path Triaxial Apparatus (BTU-TTS-5S), designed based on the Bishop-type stress path pressure cell. It is specifically used for studying the mechanical properties of saturated soils under complex stress paths. The system is equipped with a high-precision submersible load cell, an LVDT displacement sensor, a multi-channel data acquisition unit, and multiple pressure/volume controllers, enabling fully automatic control from saturation and consolidation to stress path shearing. The software includes advanced modules such as linear stress paths (p-q or s-t, with 6 forms), low-frequency cyclic loading, and k0 consolidation.

2. Test Standards

• ASTM D7181(Consolidated Drained Triaxial Compression Test)
• ASTM D4767(Consolidated Undrained Triaxial Compression Test)
• ASTM D2850(Unconsolidated Undrained Triaxial Compression Test)
• BS 1377(British Standards for soil testing)
• SL 237-1999(Chinese specification for soil testing)

3.Specification (Parameter)

4. Detail (technical details)

• Bishop stress path pressure cell: Bishop-type design suitable for saturated soil tests; max cell pressure 2000 kPa, axial force 10 kN.
• Submersible load cell: Mounted inside the pressure cell to avoid piston friction; accuracy as high as ±0.05% FS; optional ranges 5kN or 10kN.
• LVDT displacement sensor: British brand, accuracy ±0.15% FS, range 50mm, suitable for conventional specimen deformation measurement.
• Three independent volume controllers:
  • Axial pressure: 3MPa / 250cc
  • Back pressure: 2MPa / 250cc
  • Cell pressure: 2MPa / 250cc

Enables independent and precise control of cell pressure, back pressure, and axial pressure, as well as volume change measurement.

• Data acquisition unit: 10 channels, supporting 2 digital signals (e.g., LVDT, load cell) and 8 analog signals (e.g., pore pressure, volume change); 16-bit resolution.
• Stress path module: Provides 6 types of linear stress paths (p-q or s-t forms); custom paths can be defined – suitable for simulating complex stress histories.
• Low-frequency cyclic module: Supports low-frequency cyclic loading under load control mode, for simulating seismic or traffic loading.
• k0 module: Enables k0 consolidation and swelling tests.

5. Application

• Stress path studies on saturated soils: simulate stress changes during excavation, filling, unloading, and other practical engineering scenarios
• Constitutive model parameter calibration: e.g., Cam-clay model, Duncan-Chang model
• Foundation and slope engineering: strength and deformation characteristics under different stress paths
• Cyclic loading tests: soil response under subway or traffic loading (low-frequency cyclic module)
• k0 consolidation tests: determine coefficient of lateral earth pressure at rest
• Teaching and research laboratories: advanced soil mechanics testing

6. Advantages

• Bishop-type pressure cell: optimized for saturated soil stress paths, reducing errors
• High-precision submersible load cell: directly measures specimen load, avoiding piston friction
• Three independent volume controllers: independent control of cell pressure, back pressure, and axial pressure; accurate volume change measurement
• Rich software modules: covers conventional triaxial to advanced stress paths, low-frequency cyclic, k0 consolidation
• Cost-effective configuration: 10kN axial force, 2000kPa cell pressure – sufficient for most saturated soil testing needs
• Modular upgradability: additional stress path forms or cyclic loading functions can be added as needed

7. What To Choose (selection guide)

8. Process Flow

• Specimen preparation→ Prepare saturated soil specimen of Ø39.1mm or 50mm
• Mount pressure cell→ Install specimen, submersible load cell, LVDT; connect cell/back/axial pressure lines
• Saturation stage→ Back pressure saturation and B-check to verify saturation level
• Consolidation stage (optional)→ Isotropic consolidation or k0 consolidation
• Shearing or stress path stage:
  • Conventional CD/CU/UU shearing
  • Linear stress path (p-q or s-t, 6 forms)
  • Low-frequency cyclic loading (requires advanced loading module)
• Data acquisition→ 10-channel DAQ simultaneously records axial force, displacement, pore pressure, volume change, cell pressure, back pressure
• Post-processing→ Software generates stress path diagrams, stress-strain curves, effective stress paths, failure envelopes, etc.
• Report output→ Automatically generates standard-compliant tables and curves; supports printing and export

260 workers, 25000 ㎡ non-dust workshop, 16 years experience, SGS & INTERTEK certificated, one hour reach Tianjin port, this is how we keep good quality and competitive prices for global valued customers.

Our main products cover Universal testing machine, Compression testing machine, Soil,Concrete,Cement Mortar,Aggregates Rocks, Asphalt Bitumen, NDT,Pavement ,Paint,Ceramics,Drilling Fluids, Geotextiles, Textiles, Environmental,General Equipment.BTUTEST is exporting its products to more than 60 countries by offering its services through its authorized distributors and representatives.

Our main customers are private and research testing laboratories, road and general contractors, concrete and cement manufacturers, asphalt manufacturers, government authorities, ministries, engineers, consultants and re-seller. We also cooperate with accredited research centers and the most important universities in the world.we can supply more top quality product and service for more customer’s.