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Rock Multistage Triaxial Testing System

Rock Multistage Triaxial Testing System

Model: UT1072H; ASTM D7012

Rock Triaxial Testing Equipment is designed for accurate laboratory evaluation of rock strength, deformation, and failure behavior under controlled confining conditions. It is widely used in rock mechanics and geotechnical laboratories to determine elastic modulus, Poisson’s ratio, compressive strength, and stress-strain response of rock specimens under uniaxial and triaxial conditions. 

  • ·   High-stiffness load frame for stable axial loading and accurate alignment during testing.

  • ·   Controlled confining pressure and back pressure for reliable triaxial test conditions.

  • ·   Compatible with Hoek cell or high-pressure triaxial cell configurations for different specimen types.

  • ·   Load-controlled and strain-controlled testing modes for flexible laboratory workflows.

  • ·   Integrated data acquisition and software control for stress, strain, and test parameter management.

  • ·   Expandable for unconfined compression, indirect tension, permeability, hydraulic fracturing, creep, and post-failure analysis. 


General introduction

Triaxial tests are widely used in geotechnical engineering both in soil and rock mechanics. Specimens are axially loaded to failure while a confining pressure is constantly applied. As a result, the behavior of geomaterials is investigated in a three-dimensional stress state. 


UnitedTest UT1072 Series Rock Multistage Triaxial Testing System can complete the full process curve test of uniaxial/triaxial compression of rocks (soft rocks) at room temperature. Complete the full process curve test of uniaxial/triaxial compression of rocks (soft rocks) in high and normal temperature environments. Under uniaxial and triaxial conditions, perform acoustic emission testing. Complete pore water seepage tests of rocks (soft rocks) under room temperature and high temperature. Rock uniaxial compressive strength tests (program-controlled tests involving multiple stages of loading, holding, and unloading with constant stress, constant strain, constant stress rate, constant strain rate, constant displacement rate, and unidirectional cycles). The measurement system has zero-setting, calibration, continuous full-range measurement without segments, and the curve coordinates are adaptive. It can perform rate control and maintenance of test force, deformation, displacement, etc., with an overload automatic protection function that activates when axial deformation, radial deformation, time, and other parameters reach limit values or pre-settings, when the specimen breaks, when the oil circuit is blocked, and when the oil temperature is too high. It features stepless speed adjustment, force, displacement, axial and radial deformation with various control modes that can be smoothly switched at will during the test, along with curve storage and curve magnification to display various test curves. It automatically measures, controls, collects and processes data, plots curves, and can calculate compressive strength, confining pressure, axial deformation, radial deformation, Poisson's ratio, elastic modulus, etc.,

Rock Multistage Triaxial Testing System

This microcomputer-controlled electro-hydraulic servo rock (triaxial) testing machine incorporates several proprietary technologies from our company, making it advanced both domestically and internationally. 


1, the triaxial pressure chamber uses a self-balancing pressure chamber, ensuring that the rock experiences equal pressure in all directions when no axial stress is applied, and that the confining pressure does not add any extra force to the axial stress when axial stress is applied. 

2, it employs rock deformation sensors to directly measure the axial and radial deformations of the rock under both uniaxial and triaxial conditions. This measurement method is highly accurate and reliable, making it the best method for measuring rock deformation. 

3, our Automatic Triaxial Testing System uses an original imported full-digital servo controller as its control core. 

4, this automatic triaxial testing machine can perform multiple functions, including uniaxial tests, (triaxial tests), direct shear deformation tests, splitting tests, and Brazilian splitting tests, with the various functions having no interference with each other, and each test procedure being simple and easy to operate.


Features

  • Main features
  • Structure of the Main Machine
  • Pressurization System Booster

The system mainly consists of: axial compression static load control system, confining pressure loading system, pore pressure seepage system, high temperature system, and an optional acoustic emission system. Sample sizes are 50mm in diameter and 100mm high; or 50mm in diameter and 150mm high. 


2.1 The main frame of the axial compression loading machine (200-ton framework) has a stiffness of ≥10GN/m, constructed as an integrated cast portal frame, hydraulic piston assembly (loading hydraulic cylinder), pressure plates, etc. The loading hydraulic cylinder is fixed on the lower cross beam, and the piston applies the test force upward to the specimen; this structural design maximizes the stiffness of the rock triaxial testing machine, minimizes gaps in the machine, and also enhances the aesthetic appearance of the testing device.

2.1.1 An integrated automatic lifting and compressed explosion-proof pressure chamber, with automatic lifting that requires no bolts to be screwed, and a clamping lock structure; the pressure chamber has a pressure resistance of not less than 50MPa. The pressure chamber sensor leads consist of no less than 18 cores. The oil filling and draining of the pressure chamber are fully electric operations, eliminating the need for manual valve adjustments. 

2.2 The axial maximum dynamic and static loading test force ranges from 20KN to 2000kN, with an effective measurement range of 20kN to 2000kN, a frequency of 0.01-5Hz (dynamic testing is optional), load measurement precision of ≤±0.5%, and a test force loading speed range of 0.01-20KN/s. 

2.3 The confining pressure loading system utilizes a self-balancing structure for the triaxial pressure chamber, with a maximum confining pressure of ≥80Mpa, confining pressure measurement precision of ≤±0.5%FS, and confining pressure resolution of ≤0.02MPa. The confining pressure loading speed ranges from 0.001 to 0.1Mpa/s. 

2.4 Pore pressure seepage system: The maximum pore water pressure is ≥50MPa, pressure range measurement occurs within 2% to 100% of the maximum test force, precision: ≦±0.5%FS, resolution: ≤0.02MPa, water capacity: ≥800ml; the maximum pressure for gas seepage is 5MPa, with a resolution of less than 0.01MPa.

The main machine is made of an integral casting. The pressure chamber can move back and forth on the guide rails, and the pressure chamber cylinder can be raised using the lifting device, making it easy to install the specimen. The horizontal shear tester is also located on the guide rails, and during the test, aligning the specimen allows for a direct shear test to be conducted.

Rock Multistage Triaxial Testing System

This structure is composed of a cylinder body, piston, cylinder head, high-pressure sealing ring, and other components. The cylinder body and cylinder head are cast from QT500-7, and the piston is made from No. 45 steel through heat treatment and other processing. While meeting the test force requirements, it also reasonably saves test space. The actuator installs a pressure-bearing plate to drive the sample carriage for testing.

Rock Multistage Triaxial Testing System

This servo loading pump uses a Panasonic linear motor from Japan and can provide a pressure of 0-70 MPa. The pump body is made of stainless steel and features overpressure safety protection measures. There are two types of these safety protections:
1. The control software allows presetting a designated pressure. During testing, if the pressure exceeds the preset value, the software's closed-loop testing system will issue a command to stop the motor from loading, providing overpressure safety protection.
2. The entire servo loading setup includes limit switches. When the screw reaches either end, it triggers the limit switch, and the software's closed-loop testing system will also force the motor to stop loading, serving as another layer of overpressure safety protection.

Rock Multistage Triaxial Testing System

Main technical specification

Axial loading system1. Maximum test force: 1500 kN
2. Effective measuring range: 10 kN - 1500 kN (continuous)
3. Force measurement resolution: 1/250,000
4. Indication accuracy: ±1%
5. Frame stiffness: 6 GN/m
6. Control rate: 0.01 ~ 10 kN/s (continuous)
Confining Pressure Loading System1.   Confining pressure: 50 MPa
2. Measurement accuracy: ≤±2%
3. Resolution: 0.1 MPa
4. Pressurization rate: 0.01~1 MPa/s (continuous)
Deformation Measurement and Control System1.   Sample specifications Φ50X100: maximum axial deformation 8mm, maximum radial deformation 4mm
2. Measurement resolution: 0.001mm
3. Measurement accuracy: ±1%
4. Speed control range: 0.01mm-50mm/min (continuous)
Displacement Measurement and Control System
  1.  Range: 0-100mm (continuous)

  2.  Measurement accuracy: ±0.5% FS

  3.  Measurement resolution: 0.005mm

  4.  Control speed: 0.01~50mm/min (continuous)

Whole systemMaintaining a constant for a long time can last more than 360 hours
Pulse Frequency0.001-1HZ
Sample amount100   – 120 mL
Funnel upper mouth ID110mm
Bore diameter of exit mouthA:   10±0.05mm,  height: 140mm

B:   15±0.05mm,  height: 133mm

C:   25±0.05mm,  height: 120mm
Funnel mouth angle40   degree


FAQ – Rock Triaxial Testing Equipment

1. What is Rock Triaxial Testing Equipment used for?

Rock triaxial testing equipment is used to determine the mechanical properties of rock samples under controlled stress conditions. It helps evaluate parameters such as compressive strength, shear strength, elasticity, and failure behavior, which are critical for geotechnical, mining, and civil engineering projects.


2. What types of tests can be performed with Rock Triaxial Testing Equipment?

This equipment supports a variety of tests, including unconsolidated undrained (UU), consolidated undrained (CU), and consolidated drained (CD) tests. It can also perform permeability testing and stress-strain analysis under simulated in-situ conditions.


3. What industries commonly use Rock Triaxial Testing Equipment?

Rock triaxial testing systems are widely used in geotechnical engineering, mining, petroleum exploration, tunneling, dam construction, and academic research laboratories.


4. What is the typical pressure range of Rock Triaxial Testing Equipment?

The pressure capacity varies depending on the model, but most systems offer confining pressures ranging from a few MPa up to 100 MPa or higher, allowing simulation of deep underground conditions.


5. Can the equipment be customized for specific testing requirements?

Yes, many manufacturers offer customizable configurations, including different pressure ranges, temperature control systems, data acquisition software, and sample sizes to meet specific project or research needs.


6. What sample sizes are supported by Rock Triaxial Testing Equipment?

Standard systems typically accommodate cylindrical rock samples with diameters ranging from 25 mm to 100 mm and varying lengths, but custom fixtures can be designed for non-standard samples.


7. How is data collected and analyzed during testing?

Modern rock triaxial systems are equipped with advanced sensors and digital data acquisition systems that record axial load, confining pressure, pore pressure, and deformation in real time. The data can be exported for detailed analysis and reporting.


8. What are the key components of a Rock Triaxial Testing System?

A complete system usually includes a triaxial pressure chamber, loading frame, pressure control unit, hydraulic system, sensors (load cell, displacement transducers), and computer-based control and analysis software.


9. How does Rock Triaxial Testing Equipment improve project safety?

By accurately determining rock strength and deformation characteristics, engineers can design safer structures, prevent failures, and reduce risks in construction, mining, and underground engineering projects.


10. What should be considered when selecting Rock Triaxial Testing Equipment?

Key factors include maximum pressure capacity, automation level, testing standards compliance (ASTM, ISO), data accuracy, software capabilities, and after-sales technical support.


11. Is training required to operate Rock Triaxial Testing Equipment?

Yes, operators should have technical knowledge of geotechnical testing and receive proper training to ensure accurate results and safe operation of the equipment.


12. How long is the typical delivery time for this equipment?

Delivery time generally ranges from 4 to 12 weeks depending on customization requirements, production schedule, and shipping destination.

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Beijing United Test Co., Ltd.