Soil Strength (Triaxial)

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An extension of the QU test is the unconsolidated undrained test (UU); this is similar to the QU test but is run at a slower rate in order to measure pore water pressure.

By comparison, effective stresses when measured in a triaxial cell are more complex in their nature, as numerous parameters can be measured. These include back pressure, pore water pressure and volume change; all of which can be used to calculate the required engineering properties.

Effective stress tests are usually referred to as consolidated drained (CD) or consolidated undrained (CU). Generally the CD test is applicable to sands, while both the CU or CD test can be used with clays. There are many special test variations within these basic test groupings.

Our range of triaxial cells and accessories, used in conjunction with other equipment such as load frames, pressure sources and measurement devices, have been specifically designed to meet the wide ranging requirements of modern soil mechanics laboratories. Each system is easy to set up and use, providing accurate and repeatable measurements.

Triaxial Load Frames

The range of ELE designed and manufactured load frames is the most modern of its kind available to the discerning test laboratory. The range comprises capacities of 50 kN incorporating the latest microprocessor control systems, clear on-board screen displays and a range of other high quality features.

25-3518/01 Yes Yes Yes Yes Yes
25-3700/01 Yes Yes Yes No No

De-Aired Water

It is particularly important that water from which dissolved air has been removed is used in the pore pressure measurement system and saturation procedures. Any dissolved air in the water will lead to errors in the measurement of pore pressure, particularly at low pressures, and also give slow or incorrect saturation results.

Model No. Self-Contained Capacity, litres
25-1833/01 Yes 15 L
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Triaxial Cells

• Working pressure up to 1700 kPa
• All round visibility
• Sample sizes 38 to 100 mm diameter
• Rapid assembly and dismantling
• Accepts a range of interchangeable submersible load transducers
• Maximum piston load 45 kN

This range of precision made triaxial cells has been designed to meet the requirements of the modern soils laboratory. The cells have been treated to minimise corrosion. Particular attention has been paid to the quality of finish between the piston and the head. Final assembly includes the fitting of an O-ring seal and the use of special lubricant to reduce friction to a minimum and eliminate water leakage.

The piston load capacity is designed to accept high horizontal forces which may be present during the final stages of a test. Each cell has five take-off positions drilled in the base for top drainage/back pressure, pore water pressure and bottom drainage. Two no-volume change valves and an anvil for strain gauge/transducer datum are supplied for fitting to the cell.

A feature of these cells is that they all accept a single diameter piston. The internal height is such that a range of submersible load transducers can be fitted without any modification. Each cell will accept a range of base adaptors and various accessories for testing a wide range of specimens

Model No. Cell Size Weight, kg Max. Specimen Size Vertical Clearance Horizontal Clearance
25-4157 100 mm 14.3 kg 100 x 200 mm 515 mm 255 mm
25-4117 70 mm 7.3 kg 70 x 140 mm 430 mm 180 mm
25-4047 50 mm 4 kg 50 x 100 mm 380 mm 155 mm
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Automatic Data Acquisition - Triaxial

Model No. Desc
27-1753 DS7.2 Undrained Triaxial Shear Strength
27-1500/01 GDU 8 channel data acquisition unit

Accessories for Triaxial Cells

Measurement instrumentation

Various methods of measuring axial displacement, load, pressure and volume change can be supplied. All devices comply with the accuracy specified in BS 1377; ASTM D2850, D4767. All transducers transducers are supplied with a calibration certificate.

Sample Preparation

Pressure Systems

The provision and use of constant pressure systems in the geotechnical laboratory is essential if testing methods and equipment are to be fully utilised. Generally a number of independent and variable pressure sources will be required in a laboratory. Accurate and reliable monitoring systems will also be required, which may range from a single pressure guage through a whole series of transducers.