Automatic Triple-Unit Temperature-Controlled Creep Triaxial Apparatus

                                             Automatic Triple-Unit Temperature-Controlled Creep Triaxial Apparatus

1. Description

This equipment is a Fully Automatic Triple-Unit Temperature-Controlled Creep Triaxial Apparatus (BTU-TCA-3T). It is an advanced geotechnical testing system integratingtemperature control, triaxial shearing, and creep testing. It adopts adual-chamber temperature-controlled pressure celland provides precise temperature control from -30℃ to +100℃, with bothstrain-controlled and stress-controlledoperation modes. The system includes three independent testing units (triple-unit) that allow simultaneous testing of multiple specimens for creep or triaxial tests. The software covers conventional triaxial, k0 consolidation, stress path, andtriaxial creepmodules, making it suitable for long-term deformation and temperature‑coupled studies.

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2. Test Standards

• ASTM D7181(Consolidated Drained Triaxial Compression Test)
• ASTM D4767(Consolidated Undrained Triaxial Compression Test)
• ASTM D2850(Unconsolidated Undrained Triaxial Compression Test)
• ASTM D7078(Creep test methods)
• BS 1377(British Standards for soil testing)
• SL 237-1999(Chinese specification for soil testing)

Temperature control and creep aspects may follow relevant research specifications or custom procedures.

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3. Specification (Parameter )

Software modules: Data acquisition, back pressure saturation, UU, CU, CD, k0 consolidation, stress path, triaxial creep

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4. Detail (technical details)

• Dual-chamber temperature-controlled pressure cell: Dual-chamber design with circulating temperature-control liquid, reducing interference with cell pressure and volume change measurements.
• Temperature sensor embedded at specimen base: Measures the actual internal temperature of the specimen rather than ambient temperature, with accuracy ±0.1℃.
• Wide temperature control range: -30℃ ~ +100℃, covering frozen soil, high-temperature geotechnics, energy piles, etc.
• High-precision loading system: Shearing speed as low as 0.00001 mm/min, suitable for long-term creep tests; maximum axial force 30 kN.
• Dual control modes: Supports bothstrain-controlled(constant rate shearing) andstress-controlled(constant load application) modes – the latter being essential for creep tests.
• High-resolution drainage/volume change measurement: Resolution 0.001 ml, capacity ≥200 ml, suitable for detecting small volume changes during long-term creep.
• Triple-unit structure: Three independent pressure cells and loading axes, allowing simultaneous testing of three different specimens (same or different conditions), significantly improving testing efficiency.

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5. Application

• Long-term settlement studies of soft soils: Simulating creep behaviour of soft soils under constant loading
• Frozen soil and cold-region engineering: Creep and strength characteristics at sub-zero temperatures (-30℃)
• Energy piles and ground source heat pumps: Effect of temperature cycles on soil creep around piles
• Nuclear waste repositories: Long-term deformation of buffer materials under temperature‑stress coupling
• High-filled embankments and dams: Deformation prediction under long-term loading
• Constitutive model parameter calibration: Determining parameters for creep and rheological models
• Teaching and research: Complex stress‑temperature‑time coupled testing

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6. Advantages

• Wide temperature control range(-30℃ ~ +100℃): covers frozen soil, high temperature, and ambient temperature conditions
• True specimen temperature measurement: Sensor embedded at specimen base for more accurate temperature control
• Dual control modes(strain + stress): meets both creep and conventional triaxial requirements
• Ultra-low shearing speed capability: 0.00001 mm/min, suitable for long-term rheology
• High-resolution drainage/volume change: 0.001 ml, suitable for detecting small volume changes
• Triple independent testing units: Three systems independently controlled, high efficiency, suitable for comparative tests
• Modular software: Includes advanced modules such as k0, stress path, and creep
• Software: Convenient

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8. What To Choose (selection guide)

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9. Process Flow

• Specimen preparation→ Prepare saturated/unsaturated soil specimens of Ø39.1mm×80mm or Ø61.8mm×125mm
• Mount pressure cell→ Install specimen in the dual-chamber temperature-controlled pressure cell; connect cell pressure, back pressure, and pore pressure lines; embed temperature sensor at base
• Set temperature→ Set target temperature (e.g., -20℃, +5℃, +60℃); wait for temperature to stabilize (accuracy ±0.1℃)
• Saturation and consolidation→ Back pressure saturation → B-check → Isotropic consolidation or k0 consolidation (optional)
• Creep stage (stress-controlled)→ Apply constant axial stress (or constant cell pressure/deviatoric stress); record axial deformation and volume change over time
• Shearing stage (strain-controlled, optional)→ After creep, shear at constant rate to failure; determine residual strength
• Data acquisition→ Long-term monitoring (hours to months): axial force/stress, displacement/strain, volume change, drainage, pore pressure, temperature
• Parallel multi‑specimen testing→ The triple-unit system can perform creep tests on three different specimens under different temperature/stress conditions simultaneously
• Post-processing→ Plot creep curves (strain vs. time), isochronous stress-strain curves, creep rate curves, etc.; determine creep parameters (e.g., secondary creep rate, creep failure threshold)
• Report output→ Automatically generate test tables and curves; support export and printing