ZXB Series Dual-Axis Rock Creep Testing System by SINOTEST

Overview

The ZXB Series Dual-Axis Rock Creep Testing System is an electromechanical servo-controlled testing platform engineered for precise long-term mechanical characterization of quasi-brittle geomaterials under sustained multiaxial loading. Designed in accordance with fundamental principles of viscoelastic–viscoplastic deformation mechanics, the system applies independently controlled compressive loads along two orthogonal horizontal axes (typically designated σ₁ and σ₂), enabling true biaxial stress-path simulation. Unlike uniaxial creep frames, this configuration replicates in-situ stress states encountered in deep underground excavations, hydraulic fracturing zones, and dam foundation interfaces—where differential lateral confinement significantly influences time-dependent strain evolution. The system supports three primary test modes: constant-load creep (stress-controlled), constant-strain-rate loading followed by hold (strain-controlled), and stress relaxation—each executed with closed-loop feedback from high-stability load cells and sub-micron-resolution linear variable differential transformers (LVDTs) mounted on both axial actuation platens.

Key Features

• Independent dual-axis servo-hydraulic or electro-mechanical actuation with synchronized load/position control, ensuring cross-axis coupling compensation and minimal parasitic bending moments.
• Integrated high-precision displacement measurement: four LVDTs (two per axis) mounted directly on the loading platens to capture axial shortening and lateral expansion simultaneously—critical for Poisson’s ratio evolution analysis during creep.
• Real-time data acquisition at up to 100 Hz sampling rate, with onboard buffering for uninterrupted logging during power interruptions or communication latency events.
• Modular environmental chamber compatibility (optional): supports temperature regulation from −20 °C to +80 °C and relative humidity control (30–95% RH), enabling coupled thermo-hydro-mechanical (THM) creep studies.
• Rigid C-frame structural design with preloaded tie rods and hardened steel platens, minimizing frame compliance and ensuring measurement fidelity over multi-week creep durations.
• Compliance with ISO 17873:2015 (Geotechnical investigation and testing — Laboratory testing of rock — Determination of time-dependent deformation properties) and ASTM D7012-22 (Standard Test Methods for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens).

Sample Compatibility & Compliance

The system accommodates cylindrical rock core specimens (standard diameters: 50 mm, 70 mm, and 100 mm; height-to-diameter ratios of 2:1 or 2.5:1 per ISRM and ASTM guidelines) as well as prismatic concrete or mortar samples (up to 150 mm × 150 mm × 300 mm). Specimen ends are ground to ≤0.02 mm flatness tolerance to ensure uniform stress distribution. All load train components—including bearing blocks, transfer rods, and platen surfaces—meet ISO 7500-1 Class 1 accuracy requirements for force measurement systems. The system architecture supports audit-ready documentation per GLP and GMP frameworks, including electronic signatures, user access levels, and full metadata tagging (operator ID, calibration timestamp, environmental conditions) embedded within each test file.

Software & Data Management

Control and analysis are performed via SINOTEST’s proprietary TestMaster v4.2 software—a Windows-based application compliant with FDA 21 CFR Part 11 for electronic records and signatures. The software provides real-time visualization of stress–strain–time curves, automatic identification of primary, secondary (steady-state), and tertiary creep phases, and export of raw ASCII or CSV files compatible with MATLAB, Python (NumPy/Pandas), and commercial finite element preprocessors. Built-in curve-fitting modules support Burgers, Findley power-law, and Nishihara-type constitutive models. All data files include cryptographic hash verification and immutable timestamps to satisfy traceability requirements in third-party certification audits.

Applications

• Time-dependent deformation modeling of shale, granite, sandstone, and salt formations for nuclear waste repository safety assessment.
• Evaluation of long-term stability of tunnel lining interfaces under asymmetric ground pressure.
• Constitutive parameter identification for coupled THM simulations in enhanced geothermal systems (EGS).
• Creep rupture threshold determination in high-strength concrete used in arch dams and offshore foundations.
• Calibration of discrete element method (DEM) contact laws using microscale deformation histories under biaxial hold conditions.

FAQ

What specimen dimensions are supported?
Standard configurations accept Ø50 mm × 100 mm, Ø70 mm × 175 mm, and Ø100 mm × 250 mm rock cores; custom platens accommodate non-standard geometries upon request.
Can the system perform true triaxial tests?
No—the ZXB Series is strictly biaxial (two independent horizontal axes); triaxial capability requires integration with a separate confining pressure vessel (not included).
Is remote monitoring supported?
Yes—via secure TLS-encrypted Ethernet connection; users may view live plots, trigger manual holds, and download partial datasets without local workstation access.
What calibration standards does the system follow?
Force calibration traceable to NIM (China National Institute of Metrology); displacement calibration verified using laser interferometry per ISO 9283.
Does the software generate ISO-compliant test reports?
Yes—predefined templates conform to ISO 17873 Annex A and include uncertainty budgets calculated per GUM (JCGM 100:2008).