Triaxial or Biaxial Hoek Cell
The ESS Triaxial (Hoek) Cell tests the triaxial strength of rock or concrete core samples up to 40 MPa confining pressure. Its modular body accepts multiple core diameters via interchangeable confining rings and membranes, rather than requiring a dedicated cell per size.
- Core diameter (Unit 1)
- 110-150 mm, 0-30 MPa, 50 kg
- Core diameter (Unit 2)
- 70-110 mm, 0-40 MPa, 40 kg
- Core diameter (Unit 3)
- 40-70 mm, 0-40 MPa, 30 kg
Overview
In detail
How it works
The cylindrical rock sample, meeting ASTM's minimum length-to-diameter ratio of 2 with ends ground flat and parallel to 0.025-0.012 mm, is inserted within the confining membrane between two spherical seats in the triaxial loading frame. The spherical platens self-centralise and confine the sample evenly through loading. A small confining pressure and axial load hold the core in place before the triaxial test is run at the required confining pressure.
Measurement
Up to 6 sets of double orthogonal 120-ohm strain gauges are embedded in the confining membrane to determine Poisson's ratio, read via a handheld portable reader, datalogger, or third-party RS-232 device through the ESS digitiser.
Deployment
Three modular units cover core diameters from 40 to 150 mm: Unit 3 (40-70 mm, 0-40 MPa, 30 kg), Unit 2 (70-110 mm, 0-40 MPa, 40 kg) and Unit 1 (110-150 mm, 0-30 MPa, 50 kg), each accepting a minimum core length of 200 mm. Changeover kits with dedicated confining rings and membrane let one cell body serve multiple sizes, and the cell is electroplated for corrosion resistance. An optional pressurisation system (Enerpac hand pump, gauge, 1.5 m hose) and rugged 86 x 43 x 40 cm transport case are available; fittings are ¼" BSP and the design is ASTM compliant.
Reach out and say hi
Specifications
Technical specifications
- Core diameter (Unit 1)
- 110-150 mm, 0-30 MPa, 50 kg
- Core diameter (Unit 2)
- 70-110 mm, 0-40 MPa, 40 kg
- Core diameter (Unit 3)
- 40-70 mm, 0-40 MPa, 30 kg
- Minimum core length
- 200 mm
- Cell type
- Hoek
- Strain gauges
- Up to 6 x two orthogonal 120 ohm, embedded in membrane
- Digitiser
- 12-channel, serial RS-232 output
- Pressurisation system
- Enerpac hand pump with gauge and 1.5 m hose
- Case dimensions
- 86 x 43 x 40 cm
- Fittings
- ¼" BSP
Related
Often specified alongside
Geosystems
Vibrating Wire Strain Gauge SM-5
- Range
- 3000 µε
- Accuracy
- +/- 0.5% F.S.
- Temp
- −20 to +80°C
- Range
- 200 to 35,000 kPa (standard steps up to 35,000 kPa)
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