GDS Automatic Oedometer System

Product Code : GDSAOS

The GDS Automatic Oedometer System (GDSAOS) is the modern replacement for a traditional hanging weight oedometer.

The GDSAOS is a self-contained stepper motor driven unit that can be controlled  either manually using its Smart Keypad or from a PC using the USB interface. There is no requirement for compressed air or manually placed weights. When used with the GDSLAB control and data acquisition software, the GDSAOS can be used for a complete array of tests beyond those which a hanging weight oedometer can perform. 

Click here to read an article published in the Geotechnica magazine exploring the time saving benefits of using the GDS Automated AOS. 

Further Information:

Discover more consolidation system equipment for soil testing.

Key features Benefits to the user
Automatic transition between test increments for all soil types, with no need of user estimated parameters input during test set-up:

Results from tests on over consolidated clay, produced a reduction in test duration of 42%.  
Direct replacement for a hanging weight oedometer system:
The GDSAOS is a stand-alone unit (with no requirement for compressed air). Having a small footprint significantly reduces the bench space required coupled with the additional advantage that loading weights are not required.
Automated logging of data (and optionally reporting): Automation saves time recording results and controlling the test.
Incremental loading stages: When using GDSLAB the GDSAOS can be preprogrammed to include numerous incremental loading stages which automatically move to the next stage via preprogrammed end of consolidation conditions, thus increasing sample throughput.
Accurate results throughout the load range: From 1N to 10kN the GDSAOS electro-mechanical pressure controlled systems provide accurate results, compared to pneumatic consolidation systems that are typically inaccurate at low loads.
Utilise existing equipment: If upgrading from a PC logged hanging weight system, it may be possible to utilise the current consolidation cells, transducers and data loggers. Many data loggers, even those from other manufacturers, are compatible with the GDSLAB software. 
Axial Force Accuracy

0.1%FRO,

Dimensions

W/D/H - 220mm, 260mm (including keypad), 656mm

Displacement Accuracy

0.2% (Can be improved to 0.1% with an external transducer connected to an RFM)

Displacement Range

Nominal 40mm

Displacement Resolution

0.0001mm (0.1┬Ám)

Load Range (kN)

10kN (Using standard load frame, horizontal daylight 184mm)

Power

110 to 240 AC Volt Input, 60Watts, 50/60Hz

Sample Sizes

50, 63.5, 70, 100mm

  • Wide 10kN Load Frame (Horizontal daylight 224mm)
More information on consolidation test equipment.

 

Tests supported by the GDS Automatic Oedometer System, consolidation system equipment for soil testing :-

Axial Compression

An axial compression test determines the behaviour of geo-materials when the major load is applied in the axial direction. The specimen load and displacement is recorded while the specimen is compressed. Please note: Some apparatus may require additional components or software modules to perform certain tests.

K0 (K-Zero)

Kzero conditions (or specifically the coefficient of earth pressure at rest) in the context of laboratory testing are where a sample is required to be loaded whilst keeping the area of the sample a constant.  Kzero conditions are maintained in a n oedometer by design due to the radial constraint, however in an oedometer the radial stress cannot be measured therefore the K-zero condition is not measureable.  A Kzero test in a triaxial cell allows Kzero conditions to be applied and measured. The Kzero module allows you to run two tests. 

  • Test 1: Kzero using ramp RADIAL STRESS with direct radial transducer measurement: Uses a direct reading of the specimen diameter to enable the test control to maintain zero diameter change.
  • Test 2: Kzero using ramp RADIAL STRESS with back volume change measurement: Uses the change in volume of the specimen to calculate a theoretical new specimen height thus ensuring the diameter change remains zero.

Please note: Some apparatus may require additional components or software modules to perform certain tests.

Load Control (Static)

Enables application of load to a specimen for tens of seconds or more, and at frequencies less than 0.1 Hz during cyclic loading. Please note: Some apparatus may require additional components or software modules to perform certain tests.

Multi-stage Testing

The procedure for conventional triaxial tests requires three separate soil specimens to be sheared to failure under different confining pressures so that Mohr-Coulomb failure envelope can be determined and soil shear strength parameters can be obtained. An alternative procedure is the multi-stage triaxial compression test, which requires only one soil specimen to be tested at three stages of shearing with different confining pressures.


There main advantages of multi stage soil testing is the requirement for fewer soil specimens, as well as reduced testing time.  The advantage of performing the test with 3 separate samples is that if one of the samples is unsatisfactory (perhaps due to sample disturbance for example) then it is likely to be noticed when the Mohr circles are plotted, whereas this could remain unnoticed in the multi stage test. Please note: Some apparatus may require additional components or software modules to perform certain tests.

Oedometer / Consolidation

Uses a datalogger to take settlement readings from a hanging weight oedometer system.  Alternatively, GDS produces an automated oedometer which completely automates one dimensional consolidation testing.

Quasi-Static (low speed/creep) Tests

Quasi-static refers to slow speed tests.  Creep tests require accurate displacements to be measurable whilst a continuous, sometimes long term loading is accurately applied. Please note: Some apparatus may require additional components or software modules to perform certain tests.

Static Displacement

A static displacement test involves applying and maintaining a constant displacement to the specimen. The load response can subsequently be observed. Alternatively this may refer to cases where a displacement, which may vary, is applied to a specimen for tens of seconds or more. Please note: Some apparatus may require additional components or software modules to perform certain tests

Static Load

A static load test involves applying and maintaining a constant load on the specimen. The displacement response can subsequently be observed. Alternatively this may refer to cases where a load, which may vary, is applied to a specimen for tens of seconds or more. Please note: Some apparatus may require additional components or software modules to perform certain tests.

Stepped Loading

Stepped Loading provides a means to increase the specimen axial load, whilst maintaining a constant back pressure and measuring the back (pore) volume change. Please note: Some apparatus may require additional components or software modules to perform certain tests.

Standards for the GDS Automatic Oedometer System, consolidation system equipment for soil testing :-

Similar Products