GDS Instruments Product Catalogue 2015 Instruments Product Catalogue 2015 World leaders in the...

GDS Instruments Product Catalogue 2015

World leaders in the manufacture of laboratory systems for soil & rock

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About GDS Instruments

GDS Instruments (A division of Global Digital Systems Ltd) designs, develops and manufactures material testing machines and software used for the computer-controlled testing of soils and rocks. This technology is used to evaluate the mechanical properties that are key in geotechnical and earthquake engineering design.

Founded in 1979, it is estimated that GDS products have been used to help achieve over 1000 PhD’s. As well as being the first choice for academic research, GDS products have been used in many world renowned commercial laboratories for projects including the Three Gorges Dam in China, the Millau Viaduct in France, the Vasco da Gama Bridge in Portugal, Terminal Five at Heathrow and the new Crossrail link in London.

GDS employs over 40 permanent members of staff at their offices in Hook, Hampshire, UK, as well as working with a network of agents spanning 40 countries. GDS UK based staff include 3 PhD’s, 8 qualified civil / geotechnical engineers, 4 software designers, 4 hardware designers and 5 electrical/electronics specialists, allowing GDS the capability to design, build, test and ship their products directly to the customer.

Values at GDS

GDS believes in providing the best equipment for the job combined with first class support from engineers who understand the equipment and applications. GDS design and develop all their products in-house using their team

of geotechnical engineers, software designers, hardware designers (3D CAD) and electrical/electronics designers and specialists. This allows GDS to have complete control of the design, build, test and shipping process. GDS’ in-house expertise allows the capability to design bespoke systems (hardware, electronics and software), which forms a significant part of GDS’ reputation.

GDSLAB software supports every GDS computer controlled device manufactured since 1979, as well as devices from other manufacturers that have long since been made obsolete. This forms part of our unique commitment to long term customer support.

When you receive training from or ask a technical question of GDS, your reply will be from, or via a geotechnical engineer. This is our philosophy for ensuring the best service possible. Great service = repeat customers and we have many repeat customers.

GDS Customers

GDS work closely with Research and Commercial companies. Utilising our network of agents has allowed GDS to work in many countries around the world and become involved with some world renowned organisations / institutes on a variety of different projects.

Please Note: Due to continued developments, specifications of products within this brochure may change.

In 2011 GDS were awarded the prestigious Queens Award for “Enterprise in International Trade”.

GDS production and manufacturing is carried out in the UK to strict quality standards and our management systems are ISO9001 accredited.

www.gdsinstruments.com

GDS SOFTWARE 3

TRIAXIAL TESTING APPARATUSTriaxial Automated SystemTriaxial Testing System Unsaturated Triaxial Testing of SoilVirtual Infinite Stiffness Loading SystemTriaxial CellsHigh Pressure Environmental Triaxial SystemEnterprise Level Dynamic Triaxial Testing SystemAdvanced Dynamic Triaxial Testing SystemHydraulic Loading FrameLarge Diameter Cyclic Triaxial Testing SystemTrue Triaxial Apparatus

4567891011121314

ROCK TESTING APPARATUS500kN Load Frame1000kN / 2000kN Static Compression Loadframe1000kN Dynamic Actuator LoadframeHigh Pressure Triaxial Cells High Pressure Back Pressure Shearbox

1516171819

SHEAR TESTING APPARATUSShearbase System (Direct & Simple Shear)Electro-mechanical Dynamic Cyclic Simple ShearCombined Advanced Dynamic Cyclic Simple Shear Large Automated Direct Shear System (300mm) Back Pressured ShearboxDynamic Back Pressure ShearboxInterface Shear Tester Variable Direction Dynamic Cyclic Simple Shear

2021222324252627

RESONANT COLUMN & HOLLOW CYLINDERResonant ColumnSmall-Strain Hollow Cylinder Apparatus

2829

CONSOLIDATION SYSTEMSConsolidation Testing System (Rowe Type) Constant Rate of Strain Cell (In Load Frame) Automatic Oedometer System

303132

PRESSURE / VOLUME CONTROLLER RANGEEnterprise Pressure / Volume Controller up to 1MPaStandard Pressure / Volume Controller up to 4MPaAdvanced Pressure / Volume Controller up to 8MPaHigh Pressure / Volume Controllers 8MPa to 150MPaPneumatic Pressure Controller Infinite Volume Controller

333435363738

TRANSDUCERS & LOAD CELLSBender Element SystemHall Effect Local Strain TransducersLVDT Local Strain Transducers

394041

FIELD GEOPHYSICSSpectral Analysis of Surface WavesContinuous Surface Wave System

4243

Product Catalogue Contents


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Software

GDSLAB

GDSLAB is the control and data acquisition software for geotechnical laboratory applications. GDSLAB starts with a core application known as the kernel. The GDSLAB kernel allows for data acquisition from your hardware and on screen data presentation, but no test control. Simply add the appropriate module or modules to complete the test control functionality you require.

Advantages of GDSLAB include:

• Allows your existing hardware to be upgraded to PC control,

• Compatible with every GDS product since 1979, • The ability to integrate hardware from other

manufacturers. • Commercial or research testing is possible with the

choice of modules available, see the GDS website for a full list.

GDSLAB Reports

GDSLAB Reports is a National Standards (eg. BS1377:1990) laboratory test results presentation package. This program can be used to present data whether saved in a GDSLAB data file, or input by hand. Additionally, it can be used with other manufacturer’s dataloggers.

GDSLAB Reports combines the simplicity of a Windows user interface, with the power of Microsoft Excel. Data obtained using GDSLAB control and data acquisition software (or directly from your logger’s software) may be selected, viewed and manipulated where necessary before being exported directly as an Excel spreadsheet.

The GDSLAB Reports user interface is designed to manage your test data files as well as provide a means for essential user input procedures such as locating t90. The Excel template spreadsheet created by GDSLAB Reports may then be selected for a particular national standard (e.g. BS 1377). The template spreadsheet can be customised to a specific company format as required. Excel is widely accepted as the most popular spreadsheet program available today, and as such is seen as a simple interface, that many computer users can already easily manipulate. This also allows your reports to be distributed in electronic format without the need for specific software.

GDSLAB Screenshot.

GDSLAB Reports Screenshots.


www.gdsinstruments.com 4

Triaxial Automated System (GDSTAS)

Key Features: Benefits to the User:Each system may be configured exactly to the customer’s specification and budget:

The user can choose the load frame, pressure controllers, triaxial cell or just parts to integrate into existing equipment to build their ideal set-up.

Automated software control:The software directly controls the cell & back pressure, testing rate, in addition to managing all data acquisition. Automated control allows tests to proceed continuously and increases the throughput of tests.

Interchangeable range of load cells: Enables the user to run tests on soils of different stiffness and match the load transducers accordingly therefore, giving greater accuracy of results.

Submersible load cells are standard: Seal friction does not effect load readings.Standard set-ups available (ELTAS, STDTAS, ADVTAS, HPTAS):

GDS has a range of standard set-ups to help the user identify their preferred set-up. The set-ups are based on the pressure the systems will run to.

Compatible with other manufacturers products:

If a user has existing components they may incorporate them with GDS equipment to create one system and a cost saving.

Technical Specification:

Load Range (kN): 50 to 2000Pressure Range (MPa): 1 to 128Sample Sizes (mm): 20 to 300

Standards:

ASTM D-4767, ASTM D-5084, ASTM D-2850, ASTM D-2850-03a, ASTM D-7181, AS 1289.6.4.1, AS 1289.6.4.2, AS 1289.6.6.1, BS 1377-6, BS 1377-7, BS 1377-8, CEN ISO/TS 17892-8, CEN ISO/TS 17892-9, CEN ISO/TS 17892-11, JGS 0412, JGS 0521, JGS 0522, JGS 0523, JGS 0524

Tests that can be Performed:B-check saturation, unconsolidated undrained (UU) triaxial, consolidated drained (CD) triaxial, consolidated undrained (CU) triaxial, consolidation (Triaxial), constant rate of loading (CRL), constant rate of strain (CRS), slow cyclic testing, K0 (K-Zero), multi-stage testing, quasi-static (low speed/creep) tests and stress paths. Please Note - The availability of tests may depend on the hardware/software selected.

Upgrade Options:Bender element system (Vertical, Horizontal, S and P waves), hall effect local strain, LVDT local strain, laser sample measurement, very low effective stress testing and unsaturated testing.

Overview: The GDS Triaxial Automated System (GDSTAS) is a load frame-based triaxial testing system. The system is configured by choosing from a range of load frames, triaxial cells, pressure controllers and software.

The system can be configured as a multi-station commercial testing apparatus right through to a high load rock testing research level system. If existing apparatus requires upgrading, parts of the GDSTAS system can be incorporated with existing equipment (including those from some other manufacturers).


Overview: The GDS Triaxial Testing System (GDSTTS) is a fully automated triaxial testing system designed principally for stress path testing. The GDSTTS is based on the classic Bishop & Wesley type stress path triaxial cell, which controls stress directly on the sample. The system can be configured using Enterprise, Standard or Advanced level controllers (depending on the required accuracy / maximum pressure).

The 38/50mm cell can provide up to 7kN axial force, with the larger 70/100mm cells up to 25kN. This is the system of choice for teaching laboratories and research institutes.

Triaxial Testing System (GDSTTS)

Key Features: Benefits to the User:Each system may be configured to the customer’s specification and budget:

Users can choose the transducers, pressure controllers, triaxial cell or just parts to integrate into existing equipment to build their ideal set-up.

Direct actuation of axial stress through the hydraulically controlled ram in the base of each cell:

Direct axial stress application means greater accuracy for stress control.

GDSTTS can run advanced tests: Tests such as stress paths, slow cyclic and K0, all under PC control.

May be upgraded at any time: Additional transducers, software modules, bender element testing andunsaturated testing makes the system future proof.


Accuracy of Pressure Measurement: Standard: <0.15% full range. Advanced: <0.1% full rangeAccuracy of Volume Measurement: Standard: 0.25% measured value. Advanced: <0.1% measured valueLoad Range (kN): Standard: 7 or 25. Advanced: 7 or 25. High Pressure: 7 or 25Pressure Range (MPa): Standard: 1,2,3,4. Advanced: 1,2,3,4. High Pressure: Up to 10Resolution of Pressure Measurement: Standard: 1kPa. Advanced: 0.1kPa

Resolution of Volume Measurement: Standard: 1mm3. Advanced: 0.1mm3

Sample Sizes (mm): 38/50 or 70/100, upgrades available up to 150

Standards:

ASTM D-4767, ASTM D-5084, ASTM D-2850, ASTM D-2850-03a, AS 1289.6.4.1, AS 1289.6.4.2, AS 1289.6.6.1, BS 1377-6, CEN ISO/TS 17892-8, CEN ISO/TS 17892-9, CEN ISO/TS 17892-11, JGS 0412, JGS 0521, JGS 0522, JGS 0523, JGS 0524

Tests that can be Performed:B-check saturation, unconsolidated undrained (UU) triaxial, consolidated drained (CD) triaxial, consolidated undrained (CU) triaxial, consolidation (Triaxial), constant rate of loading (CRL), constant rate of strain (CRS), slow cyclic testing, K0 (K-Zero), multi-stage testing, quasi-static (low speed/creep) tests and stress paths. Please Note - The availability of tests may depend on the hardware/software selected.

Upgrade Options:Bender element system (Vertical, Horizontal, S and P waves), hall effect local strain, LVDT local strain and unsaturated testing. A high pressure STDTTS is available for cell pressure up to 10MPa.

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Key Features: Benefits to the User:Choice of different methods: To suit your testing requirements and budget, see options A, B, C & D below.

Hong Kong University of Science and Technology:

Method B has been developed in conjunction with HKUST (Hong Kong University of Science and Technology), who are specialists in unsaturated soil testing.

Mixed and matched: Methods may be ‘mixed and matched’ to create a custom system.

GDS experience:

GDS has knowledge of many different unsaturated test methods and can objectively advise customers on the best method for their test requirements. GDS are not limited to a single solution and have currently over 100 unsaturated systems in use.

Triaxial Unsaturated Testing Methods:• Method A: Direct volume change measurement of pore air and water using a GDS pore air pressure/volume controller,

water pressure controller and measurement of atmospheric pressure.• Method B: HKUST inner cell - Total specimen volume change is measured from the change in water level in an inner

cell using a differential pressure transducer.• Method C: Double walled cell - A GDS pressure volume controller is used to measure inner cell volume change which,

is directly related to sample volume change. Due to the outer cell pressurisation, the inner cell wall is considered to be infinitely stiff.

• Method D: On-sample local strain transducers measure directly on sample to calculate total volume change.


Method A: Resolution of measurement: Accuracy of measurement:

Pressure = 0.2kPa, volume = 1mm3

Pressure = <0.1% full range, volume = 0.25%

Method B:

Resolution of volume change measurement:Accuracy of sample volume change measurement:

<10mm3

Estimated at 32mm3 or 0.04% volumetric strain for a triaxial specimen 38mm in diameter, 76mm in height

Method C:

Resolution of measurement of cell volume:Accuracy of measurement of cell volume:

1mm3

0.25%

Method D: Resolution of displacement: Accuracy:

<0.1μmHall Effect = 0.8% FRO, LVDT = 0.1% FRO

Overview: GDS’ Unsaturated Triaxial Testing System (UNSAT) is an extension to traditional triaxial testing, in that soils from above the water table may be tested under conditions approaching the in-situ stress state and degree of saturation. All GDS triaxial testing systems (as well as triaxial equipment from other manufacturers*) can be modified to allow for unsaturated triaxial testing. GDS provide 4 methods to perform unsaturated testing.

Unsaturated testing can also be added to the following test types, Shear, Hollow Cylinder, Resonant Column, Consolidation and True Triaxial Testing.

*Please confirm existing equipment with GDS to check for compatibility.

Unsaturated Testing of Soil (UNSAT)


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Tests that can be Performed: B-check, consolidated drained (CD) triaxial, consolidated undrained (CU) triaxial, consolidation (Triaxial), constant rate of loading (CRL), constant rate of strain (CRS), slow cyclic testing, K0 (K-Zero), multi-stage testing, quasi-static (low speed/creep) tests, stress paths and unconsolidated undrained (UU) triaxial.

Overview: The GDS Virtual Infinite Stiffness loading system (GDSVIS) is the premier load frame in the GDS range. The loadframe allows the axial loading system to operate as though it has infinite stiffness (zero system compliance). This type of frame is unique to GDS. The frames functionality is achieved by calibration and correction of system compliance.

The GDSVIS is extremely stiff and designed principally for rock testing to allow minimum backlash at the point of sample shearing (other, less stiff load frames do not give analagous results at this critical point in the test due to the recovery of the load frame under fast unload conditions).

Virtual Infinite Stiffness Loading System (GDSVIS)


Computer Interface: USBDimensions: Nominal Size: 2.3m x 1.0m x 0.96mDisplacement Accuracy: 0.05% of full rangeDisplacement Range (mm): 100Load Range (kN): 100, 250, 400, 500

Power: 92-265v, A.C. 48-440Hz, 65w maximum, single phase three wire earthed supply, 2A fuse x 2

Weight Approx (kg): 800 to 2000 (depending on model)Resolution of measurement and control: 100kN = 3N, 250kN = 8N, 400kN = 12N, 500kN = 15N

Key Features: Benefits to the User:

Electro-mechanical actuators give superior performance, reduce space and provide cost savings:

Electro-mechanical actuators can carry out tests with greater accuracies than comparable pneumatic actuators. Mains powered means no external noisy power packs and opposed to pneumatic systems electro-mechanical systems draw only the power that is required.

Load-deformation relationship:The GDSVIS is calibrated to provide precise data on the load-deformation relationship of the entire load application and load measuring system, which is then automatically used for self compensation.

Built in feedback:All GDSVIS frames have feedback control and continuous display of axial load and platen displacement to allow simple and confident control of force and displacement.

Automatic correction: The frame provides automatic correction for system compliance, a common cause of error, which can under-estimate results of sample stiffness.

Column strength: The 500kN load frame has been built with 4 columns for extra strength and rigidity and can hold a cell size with a 700mm outer cell diameter.



Key Features: Benefits to the User:Pressure ranges: Large range of pressures available up to 100MPa.

Range of specimen size: Large range of standard sample sizes. Custom sample sizes are available upon request 20mm - 500mm diameters.

Optional balanced ram: Accurate testing with a Balanced Ram, see full description below.Low pressure cell construction: Aluminium with perspex wall making cells light weight and easy to handle.High pressure cell construction: Stainless steel for long life with no corrosion.

GDS manufactures all cells in the UK from top specification aluminium alloys and state of the art surface treatment to give our users equipment that lasts.

What are the advantages of a Balanced Ram?A balanced ram system compensates for the up thrust on the ram exerted by the cell pressure. GDS’ system utilises a secondary chamber around the ram that balances the pressure in the cell against a second piston seal such that the pressure load is not exerted onto the loadframe. This system means that a smaller range loadframe can be used to achieve the same deviator loadings on the sample. For example, if a cell has a 50mm diameter ram and a cell pressure of 32MPa this would give an upthrust of over 63kN that would have to be deducted from the maximum achievable deviator loading that a given frame can apply. With a balanced ram, the full load frame capacity may be used to apply axial force on the sample as there is zero ram upthrust. In addition, a balanced ram within a high pressure passive cell eliminates disturbance to constant cell pressure during axial loading.

Upgrade Options:Bender element system (Vertical, Horizontal, S and P waves), hall effect local strain, LVDT local strain, unsaturated testing, transducer access rings and temperature control.

Max Sample Size (mm) and Pressure Range (MPa):

Low Pressure (<5MPa) Cells: 50mm/1.7MPa, 70mm/2MPa, 76mm/3.4MPa, 100mm/1.7MPa, 100mm/2MPa, 150mm/1.7MPa, 200mm/1MPa, 250mm/1MPa, 300mm/1MPa

High Pressure (>5MPa) Cells with Balanced Ram: 54mm/64MPa, 100mm/64MPa

High Pressure (>5MPa) Cells without Balanced ram: 50mm/14MPa, 50mm/64MPa, 70mm/100MPa, 10mm/14MPa, 10mm/20MPa

Hydraulically Actuated Cells: 50mm/2MPa, 100mm/2MPa, 50mm/10MPaStandards: ASTM D-5084

Overview: GDS produce an extensive range of triaxial cells in order to satisfy the complex range of tests required by today’s modern geotechnical laboratories. In addition, there are a number of features such as balanced ram, access ports and access rings for internal transducers that are offered. In summary, the cells are grouped in the following categories:-

Traditional Passive Triaxial Cells• Low Pressure (< 5MPa).• High Pressure (> 5MPa with balanced ram).• High Pressure (> 5MPa without balanced ram)

Active Triaxial Cells (Hydraulically Actuated Triaxial).

Triaxial Cells (CELLS)


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Heating only system (Ambient to 60oc, optionally to 100oC):

The heating system works using thermal pads attached to the outside of the cell then enclosed within an environmental chamber to retain the heat. There are up to 4 temperature sensors relaying back to the control box for enhanced temperature accuracy.

Combined Cooling / Heating System (-20 to 60oC):

The cooling system uses a coiled tube section inside the cell, this is connected through the standard ports within the cell base to a glycol cooling unit, therefore temperature transfer is close to the specimen.

PC controlled: Temperature control is added to selected GDSLAB test modules to allow temperatures to be easily set for each configured test stage.

Gaseous back pressures: Can be adapted for gaseous back pressures such as Air, CO2 or Nitrogen.

Flexible system set-upThe ETAS is made up of several apparatus each of which have a number of options that can be tailored to suit specification and budget. The pressure & samples you will be testing determines the options available.

Tests that can be Performed:B-check, consolidated drained (CD) triaxial, consolidated undrained (CU) triaxial, consolidation (Triaxial), constant rate of loading (CRL), constant rate of strain (CRS), slow cyclic testing, K0 (K-Zero), multi-stage testing, quasi-static (low speed/creep) tests, stress paths and unconsolidated undrained (UU) triaxial.

Upgrade Options:Bender elements, unsaturated testing, local strain transducers and gaseous back pressures.


Load Range (kN): 50, 100, 250, 400, 500, 1000, 2000Pressure Range (MPa): 8, 14, 16, 20, 32, 64, 100Sample Sizes (mm): 38 to 150Available Temperature Ranges: -20°C to 60°C / ambient to 100°C / -20°C to 100°CStandards: ASTM D-7012, ASTM D-7070, ASTM D-7300

Overview: Based on the same features as the GDSTAS system, the main difference with the Environmental Triaxial Automated System (ETAS) is the triaxial cell and the optional temperature control system.

Two options are available, one allows heating only and the other can heat and cool the cell. All of the same features apply for this system as for GDSTAS (stress paths, slow cyclic loading etc).

Environmental Triaxial Automated System (ETAS)




Electro-mechanical system:

The ELDYN system supersedes systems using pneumatic actuators in terms of life costs and overall usable performance. Electro-mechanical systems can carry out full load dynamic testing to the stated frequency. Pneumatic systems tend to reduce the available amplitude with load due to the amount of air that needs to be moved from one side of the actuator to the other.

Cost savings, environmental benefits and safer operation:

Electro-mechanical systems are more environmentally friendly as they only draw the energy required to do the test, resulting in lower life costs. Electro-mechanical systems are also safer to run, with no high pressure air or hydraulic pipelines being required. Large noisy power packs are not required, the ELDYN only requires a standard mains electricity outlet, this reduces the laboratory space required and the installation and running costs.

Tests that can be Performed:Consolidated drained (CD), consolidated undrained (CU), consolidation (Triaxial) dynamic, cyclic loading of samples under either load or strain, slow cyclic testing, quasi-static (low speed/creep) tests, stress paths and user defined waveforms.

Upgrade Options:Optional upgrade to user defined waveforms, upgrades from 5kN to 10kN, bender elements system (Vertical, Horizontal, S and P waves), hall effect local strain, LVDT local strain and unsaturated testing.


Actuators: Highly accurate dynamic electro-mechanical actuatorAxial Displacement Encoder: YesAxial Load: +/- 5 kN at 5Hz (upgradeable to +/-10kN)Computer Interface: USBData Acquisition: 16 BitLoad Range (kN): 5 (optional 10)Operating Frequency (Hz): 5 (optional 10)Pressure Range (MPa): Depends on cell chosen (2 standard)Sample Sizes (mm): Depends on cell chosen (38 to 150 standard)

Standards:ASTM D-3999-91, ASTM D-5084, ASTM D-5311, ASTM D-2850, ASTM D-2850-03a, ASTM D-7181, AASHTO T-307-99, AS 1289.6.4.1, AS 1289.6.4.2, AS 1289.6.6.1, BS 1377-6, BS 1377-8, CEN ISO/TS 17892-8, CEN ISO/TS 17892-9, CEN ISO/TS 17892-11, JGS 0521, JGS 0522, JGS 0523, JGS 0524, JGS 0541, JGS 0542

Overview: The GDS Enterprise Level Dynamic Triaxial Testing System (ELDYN) is a triaxial system, based on an axially-stiff load frame with a beam mounted electro-mechanical actuator.

The ELDYN has been designed to fulfil the demand within the geotechnical laboratory testing industry for a lower cost, more basic dynamic triaxial testing system, yet still perform to the very advanced standards that customers expect from GDS.

Enterprise Level Dynamic Triaxial Testing System (ELDYN)


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Advanced Dynamic Triaxial Testing System (DYNTTS)

Key Features: Benefits to the User:High accuracy electro-mechanical control:

The DYNTTS system is capable of very small strain static tests through to large strain dynamic tests.

Interchangeable load cells: Allows user to accommodate very soft to very stiff soils with ranges of 1, 2, 4, 8, 10, 16, 25, 40 and 60kN.

In-built balanced ram (up to 5Hz systems):

Keeps cell pressure constant during cycling, meaning a dynamic pressure controller is not required (unless dynamic cycling of cell pressure is required).

Interchangeable pedestals and triaxial extension top caps:

Allows testing of 38, 50, 70 and 100mm diameter test specimens in the same cell.

Direct closed loop of axial displacement & axial force: Accurate control in either axial displacement or axial force mode.


Axial Force Accuracy: <0.1%Axial Force Resolution: 16bit (i.e. <0.4N for 10kN load cell, <1.5N for 40kN load cell)Axial Load (kN): 10, 16, 20, 25, 40 or 60Displacement Range (mm): 100Displacement Resolution: 0.20µmOperating Frequency (Hz): 2 (Standard), 5, 10Pressure Range (MPa): 2 (Standard), upgradeable to 5Sample Sizes (mm): 38, 50, 70, 100 (other sizes available on request up to 300)

Standards:ASTM D-3999-91, ASTM D-5084, ASTM D-5311, ASTM D-2850, ASTM D-2850-03a, ASTM D-7181, AS 1289.6.4.1, AS 1289.6.4.2, AS 1289.6.6.1, BS 1377-6, BS 1377-8, CEN ISO/TS 17892-8, CEN ISO/TS 17892-9, CEN ISO/TS 17892-11, JGS 0521, JGS 0522, JGS 0523, JGS 0524, JGS 0541, JGS 0542

Tests that can be Performed:Consolidated drained (CD), consolidated undrained (CU), consolidation (Triaxial), dynamic cyclic loading of samples under either load or strain, slow cyclic testing, quasi-satic (low speed/creep) tests, stress paths, K-Zero and user defined waveforms.

Upgrade Options:Dynamic cell pressure, larger sample sizes up to 300mm diameter, higher cell pressure up to 5MPa, Bender element system (Vertical, Horizontal, S and P waves), Hall Effect Local Strain, LVDT local strain, unsaturated testing and temperature controlled testing.

Overview: The GDS Advanced Dynamic Triaxial Testing System (DYNTTS) is a high-end testing apparatus combining a triaxial cell with a dynamic actuator capable of applying load, deformation and stresses at up to 10Hz.

The axial axis is screw-driven from an integral base unit housing the motor drive. Axial force and axial deformation are applied through the base of the cell.



Key Features: Benefits to the User:Dynamic control of axial displacement or axial force to 10Hz, sinusoidal waveform:

Direct (dynamic, 10Hz) closed loop control of axial displacement, axial force and cell pressure.

Optional dynamic control of radial stress to 10Hz sinusoidal waveform:

The dynamic control of cell pressure means that for those tests where the cell pressure is constant but the axial actuator is moving dynamically, the cell pressure actuator automatically adjusts the volume of oil in the cell to maintain a constant cell pressure. Or it can be used to cycle the cell pressure.

Optional interchangeable load cells:To accommodate soft to very stiff soils with ranges of 28, 100 and 250kN. The load frame is supplied with an external load cell to match the model maximum load range as standard.

Load frame strength: GDS load frames are extremely stiff to allow minimum backlash at the point of sample shearing.

Tests that can be Performed:Axial compression, axial extension, cyclic loading, cyclic displacement, optional cyclic cell pressure, static load and static displacement.

Upgrade Options:Triaxial testing, bender element system (Vertical, Horizontal, S and P waves), hall effect local strain or LVDT local strain, unsaturated testing and temperature controlled.


Axial Force Accuracy: <0.1% of load cell range (i.e. 1N for 10kN load cell)Axial Force Resolution: 16 bit (i.e. <0.4N for 10kN load cell, <1.5N for 40kN load cell)Displacement Accuracy: 0.05% of full rangeDisplacement Range (mm): 50 or 100Displacement Resolution: <3 µmLoad Range (kN): 28, 100, 250Operating Frequency (Hz): 0 - 10Sample Sizes (mm): Dependant on test type / cell selection, up to 300mm diameter

Standards:

AASHTO T-307-99, AS 1289.6.4.1, AS 1289.6.4.2, AS 1289.6.6.1, ASTM D-2850-03a, ASTM D-5084, ASTM D-7181, BS 1377-6, BS 1377-8, CEN ISO/TS 17892-8, CEN ISO/TS 17892-9, CEN ISO/TS 17892-11, JGS 0521, JGS 0522, JGS 0523, JGS 0524, JGS 0541, JGS 0542

Overview: The Hydraulic Loading Frames (GDSHLF) are load frames with a dynamic hydraulic actuator mounted on the cross beam for axial loading and an optional second actuator for dynamic radial stress loading. The system is capable of dynamically controlling axial displacement or axial force and can be synchronised with an optional dynamic cell pressure actuator (radial stress) to give advanced capability of dynamic stress path testing.

For performing similar tests on large particle sizes such as ballast, (see LDCTTS on page 13).

Hydraulic Axial/Radial Loading Frame (HLF28), (HLF100) and (HLF250)


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Flexible system capacity: Specimen size, load and pressures can be selected to suit specification and budget.

Interchangeable (internal submersible) load cells:

Load cells to accommodate very soft to very stiff soils with ranges of 8, 16, 25, 32, 64, 128, 250kN available. The load frame is supplied with an external load cell to match the model maximum load range as standard (100 or 250kN).

GDSDCS (dynamic control system): For data acquisition and control, 8 channels of expandable accurate high speed acquisition and control.

Direct closed-loop dynamic control of axial displacement or axial force to 10Hz, sinusoidal, triangular or user defined waveform:

Accurate and flexible control options.

Tests that can be Performed:Consolidated drained (CD) triaxial, consolidated undrained (CU) triaxial, consolidation (Triaxial) dynamic, cyclic loading of samples under either load or strain, slow cyclic testing, quasi-static (low speed/creep) tests, stress paths, resilient modulus tests and user defined waveforms.

Upgrade Options:Sample volume measurement by HKUST, bender element system (Vertical, Horizontal, S and P waves), LVDT local strain and unsaturated testing.


Axial Force Accuracy: <0.1% of load cell range (i.e. 10N for 100kN load cell)Axial Force Resolution: 16bit (i.e. <0.4N for 10kN load cell, <1.5N for 40kN load cell)Displacement Accuracy: <0.15% (i.e. <0.15mm)Displacement Range (mm): 100Displacement Resolution: 16bit (i.e. <3µm)Load Range (kN): 100, 250Operating Frequency (Hz): 0 to 10Sample Sizes (mm): 300 (standard)

Standards:ASTM D-2850-03a, ASTM D-3999-91, ASTM D-5084, ASTM D-7181, AASHTO T-294-307, AASHTO T-307-99, AS 1289.6.4.1, AS 1289.6.4.2, AS 1289.6.6.1, BS 1377-6, BS 1377-8, CEN ISO/TS 17892-8, CEN ISO/TS 17892-9, CEN ISO/TS 17892-11, JGS 0521, JGS 0522, JGS 0523, JGS 0524, JGS 0541, JGS 0542

Overview: The GDS Large Diameter Cyclic Triaxial Testing System (LDCTTS) is a hydraulically actuated load frame combined with a large diameter triaxial cell suitable for testing samples with large particle sizes such as railway ballast. The system is capable of monotonic (static) and dynamic triaxial tests as well as other advanced triaxial tests.

Large Diameter Cyclic Triaxial Testing System (LDCTTS)



Key Features: Benefits to the User:Stress or strain is applied to a 75mm x 75mm x 150mm sample independently on three axes:

Two pairs of matched dynamic rams for axes 1 and 2, and a confining fluid provides pressure for the 3rd axis on load readings.

Ram specification: Each ram has its own internal submersible load cell and displacement transducer to ensure friction effects are minimised.

Electro-mechanical actuators as standard:

Electro-mechanical actuators provide an easier to use and environmentally friendly solution for accurate testing to 5Hz. Electro-mechanical actuators mean a noisy hydraulic power pack is not required, there is no requirement to service a controller or to protect system users from noise generated by a powerpack.

Custom designed optional hydraulic actuators:

The hydraulic actuators have been custom designed by GDS to be seal-less with hydrostatic bearings. This improves the actuator performance (up to 10Hz) and reduces whole-life servicing costs as there are no piston seals to replace. Each actuator pair can be controlled in “static-mode” with either constant, ramp or slow cyclic targets in terms of load, stress or displacement.

Sample preparation:Full sample preparation equipment for cohesive and non-cohesive samples is provided with the system including a specially designed soil lathe for producing cuboidal samples.

Tests that can be Performed:Fully independent control of axis 1 and 2 for load, stress, displacement and strain, stress control on axis 3 via cell pressure. Axis 1 and 2 can be controlled at up to 5Hz or 10Hz depending on the model selected (electro-mechanical vs hydraulic).

Upgrade Options:Hydraulic 28kN actuators (10Hz), electro-mechanical 10/20kN actuators (5Hz), bender element system (vertical, horizontal, S and P waves), LVDT local strain and proximitor (axis 3 only), unsaturated testing and dynamic cell pressure (5Hz).


Data Acquisition: 16 Bit, 16 ChannelPressure Range (MPa): 2

Load Range (kN): 5, 10, 20 - Electro-mechanical 28 - Hydraulic

Overview: The GDS True Triaxial Apparatus (GDSTTA) has the defining characteristic that, unlike conventional triaxial apparatus, all three principal stresses can be controlled independently, rather than just two in a conventional triaxial system. This allows a wider range of complex stress paths to be performed. This dynamic cyclic system is powered by advanced electro-mechanical actuators or optional hydraulic actuators and is an extremely sophisticated research tool.

Vertical and one horizontal axis are loaded via the dynamic actuators (axis 1 and 2), stress control is provided for the 2nd horizontal axis, (axis 3) via cell pressure.

True Triaxial Apparatus (GDSTTA)


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System calibration: The VIS500 is calibrated to provide precise data on the load-deformation relationship of the entire load application and load measuring system.

Load frame stiffness:

GDSVIS load frames are extremely stiff and designed principally for rock testing to allow minimum backlash at the point of sample shearing (other, less stiff load frames do not give good results at this critical point in the test due to the stretch of the load frame under high load).

4 column rigidity: The load frame has been built with 4 columns for extra strength and rigidity and can hold a cell size with a 700mm outer cell diameter.

Feedback control: The VIS500 comes with feedback control and continuous displays of axial load and platen displacement.

USB computer interface: May be used stand-alone using the keypad supplied or under computer control.

Tests that can be Performed: Axial compression load, axial displacement, axial extension load and cyclic (slow speed) load or displacement.

Upgrade Options:Extra tall columns allow heavy cell tops to be raised from their boxes using the automatic cross beam raising and lowering mechanism, making sample preparation quick and easy for a single operator.

Hydraulic column locks replace the standard torque wrench tightened bolts, allowing the user to quickly and easily exert clamping forces when adjusting the height of the frame.


Computer Interface: USBDisplacement Accuracy: 0.05% of full rangeDisplacement Range (mm): 100Load Range (kN): 500Data Acquisition: 16 Bit 4 ChannelResolution of Measurement and Control: <0.1% full range, displacement = 0.1micrometre

Overview: The GDS 500kN Virtual Infinite Stiffness loading system (VIS500) is the premier load frame in the GDSVIS range. VIS stands for virtual infinite stiffness, it allows the axial loading system to operate as though it has infinite stiffness (zero system compliance). This type of frame is exclusive to GDS.

The 500kN version of the VIS has the added advantage that the beam lift can be used to lift the cell top on/off the cell base (extra long columns as an option) as well as options for hydraulic clamps to hold the beam in place.

500kN Load Frame (VIS500)




To increase efficiency and to reduce whole life costs the actuator is powered by a 200cc / 64MPa GDS Advanced pressure controller:

This efficiency means that the full load of the frame can be achieved by drawing less than 1000 Watts (1kW) from mains electricity in place of a hydraulic power pack which can draw up to 50kW. Control is carried out by a GDS advanced pressure controller and as such is very stable and accurate. No special requirements are needed to host or service a controller or to protect system users from noise generated by a powerpack.

The static frame uses low pressure compressed air on the reverse side of the actuator to raise the actuator post compression:

This allows a simple manual regulator to be set with a small pressure in the upper chamber of the actuator. This innovation allows lower stress testing to be carried out more efficiently and more accurately without the cost implications of using a second pressure controller for the upper chamber of the actuator. Once the regulator is set it can then be left unattended for all tests, so long as a supply of clean, dry compressed air is available at a pressure greater than 0.5MPa (5Bar).

Ideal for creep and relaxation testing: Ideal for use where displacements are very small and loads needs to be very stable and well controlled.

Infinite Volume Controller option: For tests where continuous displacement is required to amplitudes greater than 5mm.

Tests that can be Performed:Load control and axial displacement control.

Upgrade Options:Triaxial, additional 64MPa controller and Infinite Volume Controller for tests where continuous displacement is required, additional data acquisition channels, an extensive range of Triaxial and Hoek cells are available to a complete triaxial testing solution for rocks and temperature control (up to 200 Degrees C).


Actuators: HydraulicDimensions (mm): Frame footprint 700 x 600 x 1850Displacement Range (mm): 100Load Range (kN): 1000 / 2000Weight (kg): 1725

Overview: The GDS Static Loadframes are actuated from the base by a hydraulic actuator at loads up to either 1000kN or 2000kN. To increase efficiency and to reduce whole life costs the actuator is powered by a 200cc / 64MPa GDS advanced pressure controller. This efficiency means that the full load of the frame, can be achieved by drawing less than 1000 Watts from mains electricity in place of a hydraulic power pack which could draw up to 50kW, to achieve similar loads.

1000kN (1MN) / 2000kN (2MN) Static Compression Loadframes (HLF1000-S), (HLF2000-S)


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Key Features: Benefits to the User:The HLF1000-H has closed loop-feedback control of force and position as standard:

This allows the frame to be used for many different test types from soil to rock mechanics and other material test applications where precise control of axial force and displacement are required in a very stiff reaction frame (2GN/mm).

Compact design: Reduces the laboratory floor space required, only 2430mm x 750mm x 700mm.

Hydraulic power: Hydraulic power is derived from a separate powerpack that can be sited up to 15m from the loadframe.

ELDCS control system:This loadframe is controlled by the ELDCS control system which, has 4 channels of high speed data acquisition built in and is connected to the PC via the USB bus.

Closed loop-feedback control of force and position as standard:

The loadframes have closed loop-feedback control of force and position as standard. This allows the frame to be used for many different test types from soil to rock mechanics and other material test applications where precise control of axial force and displacement are required in a very stiff reaction frame.

Low friction, bidirectional actuator: Full system load is available in compression and tension.

Tests that can be Performed:Axial compression, axial extension, load control (Static), load control (Dynamic), displacement control (Static) and displacement control (Dynamic).

Upgrade Options:An extensive range of Triaxial and Hoek cells are available to a complete triaxial testing solution for rocks and Temperature control (up to 200 Degrees C).


Actuators: HydraulicDimensions: Dependant on chosen specificationsDisplacement Accuracy: 0.2% FRODisplacement Range (mm): 100Load Range (kN): 1000Max Loading Frequency (Hz): 2.5Data Acquisition: 4 Channel 16 Bit

Overview: The GDS 1000kN Dynamic Loadframe (HLF1000-H)is a servo-hydraulic system that has been designed to be a compact and effective addition to a soil and rock testing laboratory.

Hydraulic power is derived from a separate powerpack that can be sited up to 15m from the loadframe.

Two versions of the 1MN loadframe are available:• 4 Column Moveable Head - where different sized test

cells are to be used.• Fixed Heads.

1000kN Dynamic Load Frame with Hydraulic Actuator (HLF1000-H)



What is a Balanced Ram?The balanced ram is a system that compensates for the up thrust on the ram exerted by the cell pressure. Our system utilises a secondary chamber around the ram that balances the pressure in the cell against a second piston seal such that the pressure load is not exerted onto the loadframe.

This system usually means that a smaller range loadframe can be used to achieve the same deviator loadings on the sample. For example if a cell has a 50mm diameter ram and a cell pressure of 32MPa the up thrust would be approximately 63kN on the frame. This would have to be deducted from the maximum achievable deviator loading that a given frame can apply. With a balanced ram, the full load frame capacity may be used to apply axial force on the sample as there is zero ram upthrust. In addition, a balanced ram within a high pressure passive cell eliminates disturbance to constant cell pressure during axial loading.


Large pressure range: GDS triaxial cells are available from 4 to 100MPa, allowing the user to choose the ideal cell for their range of testing needs.

Large variety of sample sizes: GDS range of cells can hold samples up to 100mm at a variety of different pressures.

3rd party frames: GDS Triaxial cells can be supplied as part of a complete system or for use in pre-existing 3rd party loadframes.

Temperature control: Versions of some cells are available for testing samples at elevated temperatures up to 1500C.

Stainless steel design:All GDS high pressure cells are made from stainless steel and as such they will give many years of use without tarnishing or needing to be replaced due to corrosion.

Balanced ram: GDS high pressure triaxial cells are available with or without a balanced ram.


Pressure Range (MPa):

High Pressure Passive cells with balanced ram; max sample size/pressure range: 54mm/64MPa, 100mm/64MPa.High Pressure (>5MPa) Passive cells without balanced ram; max sample size /pressure range: 50mm/14MPa, 50mm/64MPa, 70mm/100MPa, 10mm/14MPa, 10mm/20MPa

Overview: GDS produce cells for 20 to 100mm and from 4 to 100MPa to satisfy the complex range of tests required by today’s modern geotechnical laboratories. Cells are available with or without balanced ram.

High Pressure Triaxial Cells (CELLS-HP)


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Realistic slope stability conditions: Conditions can be applied by accurately controlling the normal force, shear force and back pressure.

Highly accurate displacement measurement: For very small yet long term creep movements to be measured.

Direct shear testing: Allows direct shear tests to be performed under closely controlled conditions in terms of axial load and back pressure.

10MPa stainless steel cell: For back pressure control and pore pressure measurement.Provide accurate results whilst working at high loads: Up to 100kN axial and shear load.

Tests that can be Performed:Monotonic shear, cyclic (slow speed) shear and creep tests (under load or displacement control).

Upgrade Options:Small strain shear LVDT system.


Computer Interface: USBData Acquisition: 16 bit

Load Range (kN): 100 Axial100 Shear

Operating Frequency (Hz): Quasi Static (capable of slow speed cyclic testing, periods around 5 minutes)Pressure Range (MPa): 10Sample Sizes (mm): 50 diameter or 100 diameter cylindrical, 50 highStandards: ASTM D-5607, JGS 0560, JGS 0561

Overview: The GDS High Pressure Back Pressure Shearbox (HPBPS) is a high pressure, high load version of GDS standard back pressure shearbox and is able to perform direct shear tests with precise back pressure control, for the direct control and measurement of realistic slope failure.

The device can load the sample to 100kN axially and in shear whilst also being capable of applying up to 10MPa back pressure.

High Pressure Back Pressure Shearbox (HPBPS)

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Desktop apparatus: This desktop apparatus comes with built in controllers, resulting in a small footprint of just H x 660mm, L x 660mm, D x 220mm.

Runs from mains electricity:The GDSSS comes with an integrated power supply, meaning the only laboratory service required for the system is mains electricity (110Vac – 240Vac).

No requirements for compressed air or hanging weights: The apparatus is a fully self contained, no lifting of heavy hanging weights.

Normal (axial) and shear forces are applied using GDS electro-mechanical force actuators:

The use of GDS force actuators makes the system very flexible, each axis can be controlled in displacement (strain or velocity) mode as well as load control.

Topcap fixity: Topcap fixity is assured through a system of crossed roller linear guides to minimise topcap rocking during shearing.

Sample preparation and topcap support apparatus:

Simple shear sample preparation and insertion into the system is made easy by using the included sample preparation and topcap support apparatus. This ensures that no load is applied to the sample during preparation and insertion.

Closed loop feedback: Axial and shear load readings are controlled under closedloop feedback.

Fully automated:For direct shear, once the shear gap has been set, the test can complete with no further user intervention. For simple shear, once the top-cap is docked all consolidation and shearing stages can proceed with no further user intervention.

Tests that can be Performed:Direct and simple shear tests.

Upgrade Options:The GDS Shearbase can be upgraded to allow the system to perform both simple and direct shear tests. This is done by swapping the pedestal and top cap for a shear box. Simple Shear Options: 10kN axial upgrade and Bender Elements. Direct Shear Options: 10kN axial upgrade.


Data Acquisition: 16 BitLoad Range (kN): 2.5, 5, 10Sample Sizes (mm): Up to 100Standards: ASTM D-6528, ASTM D-3080, CEN ISO/TS 17892-10, JGS 0560, JGS 0561

Overview: The GDS Shearbase System (GDSSS) is an electro-mechanical shear testing device that can be configured for either simple shear or direct shear testing.

One benefit of this apparatus is that the conversion between simple shear and direct shear is easy and therefore if both options are not supplied at time of build, the upgrade can be supplied at a later date. The Shearbase system can carry out fully automated simple shear, and direct shear tests (after shear gap settings).

Shearbase System (GDSSS)


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Teflon coated low friction retaining rings: A cylindrical soil specimen is laterally confined by teflon coated low friction retaining rings, ensuring a constant cross sectional area (or K-zero conditions).

Electro-mechanical actuators that give superior performance, reduce space and provide cost savings:

Electro-mechanical actuators can carry out tests up to +/-1mm at 5Hz, with greater accuracies than comparable pneumatic actuators. Mains powered means no external noisy power pack are required and as opposed to pneumatic systems electro-mechanical systems draw only the power that is required.

Active height control: Therefore constant volume conditions are enforced i.e Simple Shear. No manual intervention between stages plus little or no effects of vertical compliance.

Axial & Shear linear guidance provided by super-stiff crossed-roller bearings:

200mm bearing length not only provides stability while ensuring minimal rotation of the topcap during shearing, allowing testing to be simple shear rather than rotational motion, but also provides high load capacity with low friction with accurate linear guidance.

GDS shear loadcell: Designed so that shear force is measured in front of the linear guides, as such the shear force measurement does not include frictional errors.

Tests that can be Performed:Cyclic and quasistatic simple shear.

Upgrade Options:P and S wave measurements with bender element system and small strain measurement system.


Data Acquisition: Integrated, with 8 input channels up to ±10v, 16 bit A/D convertersDimensions (mm): 1200 (H) x 500 (L) X 770 (D)

Displacement Range: Axial: +/- 25mm, Shear: +/- 15mm: Accuracy = <0.1% FSO (In practice, axial range is +/-50mm to aid sample placement, measured stroke is +/- 25mm)

Displacement Resolution: 16 bit (i.e. +/- 20mm = 0.6μm, +/- 15mm = +/- 0.5μm, +/- 2.5mm = <0.1μm)Load Range (kN): 5 or 10Operating Frequency (Hz): 0 to 5Power: 240V or 110V 50/60Hz 1 phSample Sizes (mm): Up to 100Weight Approx (kg): 160Standards: ASTM D-6528

Overview: The GDS Electro-mechanical Dynamic Cyclic Simple Shear Device (EMDCSS) is for simple shear testing only. It is capable of carrying out dynamic cyclic tests from small strain (0.005% shear strain amplitude) to large strain (10% shear strain amplitude), as well as extremely accurate quasi-static testing.

This is the choice for a no-compromise simple shear machine with the greatest range of testing capability. The perfect choice for advanced commercial testing or academic research.

Electro-mechanical Dynamic Cyclic Simple Shear (EMDCSS)




Electro-mechanical actuators that give superior performance, reduce space and provide cost savings:

Electro-mechanical actuators can carry out tests up to +/-1mm at 5Hz, with greater accuracies than comparable pneumatic actuators. Mains powered means no external noisy power pack is required and as opposed to pneumatic systems electro-mechanical systems draw only the power that is required.

Easy sample saturation:The ADVDCSS can saturate simple shear samples in a similar way to normal triaxial testing, using cell pressure and back pressure. This cannot be achieved in a normal simple shear system.

Accurate testing:Direct closed loop control of axial and shear force and direct closed loop of normal and shear displacement control leads to accurate testing with no user tuning / intervention during a test.

High accuracy results: The ADVDCSS has been designed to be extremely stiff in the axial and shear directions, this leads to very low system compliance and high accuracy results.

Teflon coated low friction slip rings: During simple shear tests constant volume conditions are ensured in the sample by use of teflon coated low friction slip rings around the sample.

Independent control of axial axis and shear axis:

Allows tests such as out of phase loadings. Preprogrammed sine, havesine, triangular and square waveforms provides ease of use for standard tests.

Increased strength and alignment: High quality, low friction linear guides are used to ensure strength and alignment in normal and shear directions.

Tests that can be Performed:Consolidated drained (CD) triaxial, consolidated undrained (CU) triaxial, consolidation (Triaxial), cyclic loading of samples under either load or strain, slow cyclic testing, quasi-static (low speed/creep) tests, stress paths, user defined waveforms, cyclic simple shear, K-zero, permeability and simple shear.

Upgrade Options:Bender element testing, unsaturated testing (Method A & D) and to local strain measurement (triaxial).


Data Acquisition: 8 Channel Dynamic 16 Bit data loggerLoad Range (kN): 5, 10Sample Sizes (mm): 50, 70, 100Standards: ASTM D-6528

Overview: The GDS Combined Advanced Dynamic Cyclic Simple Shear (ADVDCSS) is a testing system that can be used for dynamic cyclic simple shear and dynamic triaxial testing.

The ADVDCSS allows the principal stress direction to continuously rotate through 90 degrees, giving the ability to simulate the stress states common to many geotechnical problems, including earthquake loading. Then, by moving the machine into ‘triaxial mode’ and installing the longer cell wall, the device may be used for dynamic and static triaxial tests.

Combined Advanced Dynamic Cyclic Simple Shear (ADVDCSS)


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Large Automated Direct Shear System (300mm)((GDSLADS)


Electro-magnetic actuation: Runs from mains electricity (no hydraulics or pneumatics) therefore reducing the space required and providing a more accurate system.

Electro-magnetic & normal force application: No hanging weights, hydraulics or pneumatics.

Automated data logging (multiple stage tests):

Testing can run unattended over night and at weekends to increase throughput and reduce staff costs. Multiple stage tests can be preprogrammed and saved in GDSLAB.

Cylindrical or square samples can be supplied, as well as multiple sample boxes:

GDSLADS has the flexibility to test different shaped samples allowing the user greater flexibility of use, along with increased throughput of tests via multiple sample boxes.

Built in loadcells (Standard 100kN, other ranges can be provided):

Interchangeable loadcells allow lower range loadcells to be used for more accurate low stress testing.

Stiff construction: To reduce equipment compliance and increase accuracy.After setting of shear gap no further user intervention is required: Automated test control and a greater throughput of samples.


Actuators (kN): 100 Shear force actuator100 Normal force actuator

Data Acquisition: 16-bit data acquisitionLoad Range (kN): 100Sample Sizes (mm): Up to 300 x 300 x 150Weight Approx (kg): 450Standards: ASTM D-5607, CEN ISO/TS 17892-10, JGS 0560, JGS 0561

Tests that can be Performed:

Different sample sets can be used to achieve the following types of testing in one system:• Standard direct shear up to 300mm x 300mm.• Geomembrane shear test.• Rock mechanics sample set.

Overview: The GDS Large Automated Direct Shear System (GDSLADS), is a state of the art system that extends the boundaries of traditional shear testing. The GDSLADS automates the loading procedures as well as data acquisition and presentation. Normal and Shear forces are applied by GDS force actuators so they are controllable in terms of stresses and strains in both directions.

The system is floor mounted and self-contained. No pneumatic/hydraulic powerpacks are required, only mains electricity. Tests can be controlled from either the keypads and displays associated with the force actuators or via GDSLAB software.




Internal loadcell: Internal loadcell for shear and optionally normal force for load measurements as close to the sample as possible for greater accuracy.

Rigid aluminium cell body: To reduce system compliance.

Unsaturated GDSBPS:The unsaturated GDSBPS is based on a standard, saturated device but modified to allow the measurement and control of matric suction (the difference between the pore air and water pressures).

Real-world situations to be modelled in the laboratory:

All versions allow the pore pressures within the sample to be controlled. The control of pore pressure during direct shear testing allows real-world situations to be modelled in the laboratory.

Optional low-cost version: Low-cost version available which uses hanging weights for axial load.


Data Acquisition: 8 channel, 16 bit with, serial interface and 8 user definable gain ranges from 10mV to 10V input

Dimensions (mm): L= 875 x W = 350Displacement Accuracy: <0.1% FSODisplacement Range: Axial = +/- 15mm, Shear = +/- 25mmPower: 240V or 110V 50/60Hz single phaseResolution of Measurement and Control: 16 bit, ± 25mm = ± 0.7μm (shear), ±10mm = ±0.3μm (axial)

Sample Sizes (mm): 75 x 75 (alternative sizes available on request)Standards: ASTM D-3080, CEN ISO/TS 17892-10, JGS 0560, JGS 0561

Upgrade Options:

The GDSBPS apparatus can be specified with many different options, some are noted below but many more are available. Please contact GDS if the required specification is not listed here or if higher pressures / forces are required. Upgrade to unsaturated back pressured shear box, increase maximum back pressure from 1MPa up to 10MPa, increase maximum axial shear and shear load from 5kN up to 100kN. Upgrades also include normal (axial) load upgrade to electro-mechanical actuator and the addition of bender elements.

Overview: The GDS Back Pressure Shearbox (GDSBPS) has the ability to perform direct shear tests with precise back pressure control, for the recreation and measurement of realistic slope failures.

The BPS range includes a saturated version (control of pore water pressure), an unsaturated version (control of both pore water and pore air pressure) and a dynamic version, see page 25.

Developed in conjunction with the University of Durham, UK (saturated version) and Zhejiang University, China (unsaturated version).

Back Pressured Shear Box (GDSBPS)


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Dynamic Back Pressure Shearbox (DYNBPS)


Electro-mechanical actuators:Designed for long life and highly accurate position control. Unlike pneumatic actuators this type of actuator is suitable for carrying out small strain testing, long term creep tests and dynamic tests up to 5Hz.

Realistic modelling: The DYNBPS provides a realistic model of many real-world cyclic and seismic geotechnical problems, such as slope stability and earthquake loading.

Interchangeable internal load cells: For increasing accuracy and resolution on soft soils.Closed-loop control: For shear force/displacement and normal force/displacement.Shear gap: Manually set-able from outside the pressure vessel whilst under pressure.

Balanced rams: Allows cost effective static pressure controllers to be used for back pressure with minimal pressure fluctuations during dynamic tests.


Axial Force Resolution: 16bit (i.e. <0.4N for 10kN load cell, <1.5N for 40kN load cell)Computer Interface: USBData Acquisition: 16bitDimensions (mm): 1200(H) x 500(L) x 770(W)Load Range (kN): Normal force 25, Shear force 10Operating Frequency (Hz): 5 Power: 3 phasePressure Range (MPa): 1Resolution of Measurement and Control (MHz): 10

Sample Sizes (mm): Square: 50, 75 (custom sizes available on request), Sample height: 20-40Weight Approx (kg): 160Standards: CEN ISO/TS 17892-10

Tests that can be Performed:Back pressured static direct shear tests, back pressured cyclic shear load tests and back pressured cyclic shear displacement tests.

Upgrade Options:Bender elements and small strain transducers.

Overview: The GDS Dynamic Back Pressured Shearbox (DYNBPS) is used for static and dynamic direct shear testing on soil specimens with control of sample pore pressures. The control of pore pressure during direct shear testing allows real-world situations to be modelled in the laboratory.

This dynamic version of the device allows a landslide to be modelled as it quickly gains velocity after the initial moment of failure. Cyclic direct shear testing is also possible while still controlling and measuring pore pressure.



Interface Shear Tester (GDSIST)


GDS force actuators for axial stress: Accurate electro-mechanical control of axial force and displacement with keypad + display for local control.

Interface friction studies: The most common uses for the GDSIST include studies of interface friction, for example between geomembranes, pipline footings and natural materials.

Load cells: Low range load cell for accurate low stress testing of axial load and torque.Stainless steel: Available in stainless steel for corrosive sample testing.

Internal submersible load cell: This allows the user to measure friction between the sample and material without errors being introduced by the seal friction on the ram.

Tabletop Apparatus Small laboratory footprint.

Tests that can be Performed:Axial or radial deformation, consolidation undrained, constant rate of strain, oedometer / consolidation, stepping loading, controlled hydraulic gradient, unsaturated tests, consolidation drained, constant rate of loading and saturation ramp.

Upgrade Options:

Unsaturated testing.


Actuators: 1 off vertical, 1 off torsionalAxial Force Accuracy: ±0.2%Axial/Torque Force Range: 1kN/10Nm to 5kN/100NmComputer Interface: USBLoad Range (kN): 1Power: 240V, Control systems: 100-240V~1.6A MAXPressure Range (MPa): 1, (2MPa cell available upon request)Sample Sizes (mm): 38, 50, 70, 100, other sample sizes available upon request

Overview: The GDS Interface Shear Tester (GDSIST) has been designed to test the shear interface between the soil specimen and the sample top-cap. Top-cap interfaces of differing roughness can be used to stimulate differing insitu conditions. The GDSIST is a CRS consolidation cell with the ability for the base pedestal to infinitely rotate. The internal load cell measures the axial force on the specimen as well as the applied torque.


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Test control: Test control allows specification of amplitude of shear stress/strain as well as direction.

Direction of shear and pattern of shear rotation from zero degrees can be defined:

• Constant at zero degrees. • Ramp from zero degrees to x degrees in n seconds.• Cycles from zero degrees plus or minus x degrees with period in seconds.

Teflon coated rings: K-zero conditions ensured by use of 1mm high, low-friction, teflon coated rings.GDSLAB can also define test stages at different shear stress:

Angles relative to zero e.g. 0, 10, 20, 30 etc. Definition of waveform by datum/common point, amplitude, controlling parameter and frequency.

Independent axis control: Each axis can be stress / load controlled or strain controlled.Local strain LVDT’s for both shear directions:

Highly accurate strain measurement / control. Local LVDT is used for active height control during constant volume tests.

Tests that can be Performed:Simple shear and variable direct simple shear.

Upgrade Options:

Local strain LVDT’s for both shear directions and bender elements.


Actuators: 3 x electro-mechanical, high accuracy, encoder controlled actuatorsAxial Force Accuracy: Typically <0.1%Axial Load (kN): 5

Displacement Range: Shear axis +/- 10mm (+/-30% shear strain)Normal axis +/- 25mm (+80% consolidation strain)

Displacement Resolution: 0.3µmLoad Range (kN): 5 normal force, 2 on each shear measurement (y and z)Operating Frequency (Hz): 1Sample Size (mm): 50 diameter specimen, height 20 to 30 (other sizes on request)

Overview: The GDS Variable Direction Cyclic Simple Shear (VDDCSS) allows simple shear to be performed in two directions, rather than the standard single direction. This is achieved by having a secondary shear actuator that acts at 90 degrees to the primary shear actuator.

The VDDCSS is similar in principle to the EMDCSS machine, except for the additional horizontal axis. When used as a variable direction machine, the secondary shear axis can be used independently of the other shear axis or in conjunction with it, therefore simple shear may be performed in any horizontal direction. Tests can be carried out with constantly rotating shear vectors.

Variable Direction Dynamic Cyclic Simple Shear (VDDCSS)




RCA systems that GDS supply are current driven using a transconductance power amplifier:

This is because the impedance of magnet / coil devices change with frequency. At higher frequencies, using a constant voltage amplifier the current would be seen to reduce. As the torque is directly proportional to current, the torque will also reduce and a non-linear torque input would affect results. This effect is removed in the GDSRCA by using a current driven power amplifier.

Designed to provide maximum rigidity: Providing minimum losses and a more consistent frequency response and no rigid support to the top cap so it is completely free vibrating.

Dedicated software is used for control and data acquisition of apparatus: Simple automated tests.

Low equipment damping:The software switches the hardware to provide an ‘open circuit’ through the coils during free vibration decay, which prevents ‘back’ EMF generation and reduces equipment damping effects.

Electro-magnetic drive system: Which incorporates precision wound coils and composite sintered neodymium iron boron (NdFeB) “rare-earth” magnets.

Internally mounted, counter-balanced accelerometer: Used to measure vibratory response of the sample.

Internal cell: To surround the sample with water and to avoid air penetrating the membrane.

Tests that can be Performed:Damping ratio in flexure, damping ratio in torsion, resonance in flexure, resonance in torsion and optional slow speed (<2Hz) torsional shear.

Upgrade Options:Lifting frame for easy cell top removal, vertical bender elements (S and P wave), unsaturated RCA testing pedestals, torsional shear upgrade using non-contacting proximetor transducer, high pressure upgrades from 1MPa (standard) to 2MPa, 3MPa or 25MPa, anisotropic test upgrade (hanging weights), gas hydrate upgrade option, unsaturated testing (Method A and B), option for environmental temperature chamber (-20 degs C to +40 degs C), an axial loading actuator and frame and a Hardin Oscillator type actuator with axial force actuator.


Frequency Range (Hz): 300Pressure Range (MPa): 1 standard, 2, 3 and 25 as optionsSample Sizes (mm): 50, 70, optionally 100Standards: ASTM D-4015

Overview: The GDS Resonant Column Apparatus (GDSRCA) is a true fixed free resonant column where one end of a confined solid or hollow cylindrical soil specimen is excited and the other is fixed. From the resonant frequency, small strain stiffness can be found.

GDSRCAs are used by advanced commercial laboratories and Universities for performing research.

Resonant Column (GDSRCA)


29

Key Features: Benefits to the User:Both systems exhibit high levels of axial and torsional stiffness coupled with the minimum amount of “backlash” and friction:

Resulting in both machines being well suited for small strain testing right through to high load and strain testing.

Flexibility in the capacity of the system: Specimen size, load, pressures can be chosen to ensure the system is created specifically to suit the testing requirements.

Balanced ram: Allows a static pressure controller to be used for cell pressures with no significant fluctuations of cell pressure during dynamic tests.

Submersible, interchangeable combined axial / torque loadcell:

Measures axial load/torque with no errors introduced due to friction on the loading ram.

Cell top lift frame: For ease of use when lifting the cell top, comes as standard.

Tests that can be Performed:HCA generalised stress path (P, Q, B, α), advanced HCA loading procedures and dynamic HCA loading. Triaxial testing with optional items.

Upgrade Options:Sample sizes, transducers, celltop counter balanced lift, optional large cell for 200mm samples, internal bore LVDT, outside diameter non-contacting proximetors and unsaturated testing.


Axial Displacement Encoder: <1μmAxial Load Resolution: 0.3N (for 10kN systems)Axial/Torque Force Range: 10kN/200Nm, 12kN/200Nm, 15kN/400NmTorque Resolution: 0.06kN (200kN Systems)

Dimensions (mm): 700 X 700 X 1000 (cell de-mounted), 1450 (cell mounted), 2350 with cell top lifting frame

Load Range (kN): 10, 12 or 15Operating Frequency (Hz): 0.5, 1, 2 or 5Pressure Range (MPa): 1, 2Sample Sizes (mm): 100/60/200 or 200/160/400 (OD, ID, height)Weight Approx (kg): 500

Overview: The GDS Small-Strain Hollow Cylinder Apparatus (SS-HCA) allows for rotational displacement and torque to be applied to a hollow cylindrical specimen of soil. Using this device it is possible to control the magnitude and direction of the three principal stresses.

Two version of the apparatus are available, SS-HCA s (static) and SS-HCA d (dynamic).

Small-Strain Hollow Cylinder Apparatus (SS-HCA)



Key Features: Benefits to the User:Rowe and Barden type cell: Direct stress control on specimen via either a flexible or rigid porous disk.

Flexibility in the capacity of the system: Specimen size, load, pressures can be chosen to ensure the system is created specifically to suit the testing required and the budget.

Advanced testing (ADVCTS):

Remains the leading Rowe & Barden type consolidation system for research testing throughout the world. All elements of the ADVCTS system are biased towards achieving the greatest resolution and accuracy, for the highest quality tests achievable in a research environment.

Standard testing (STDCTS):Provides a low cost alternative with all the features of the ADVCTS system with slightly reduced accuracies by using GDS standard pressure/volume controllers.


Accuracy of Pressure Measurement: Standard set-up (STDCTS): <0.25% measured valueAdvanced set-up (ADVCTS): <0.1% full range

Accuracy of Volume Measurement: Standard set-up (STDCTS): <0.25% measured valueAdvanced set-up (ADVCTS): <0.1% measured value

Data Acquisition: 16 BitResolution of Measurement and Control:

Standard set-up (STDCTS): 1kPaAdvanced set-up (ADVCTS): 0.5kPa

Resolution of Volume Measurement: Standard set-up (STDCTS): 1mm3

Advanced set-up (ADVCTS): 0.5mm3

Sample Sizes (mm): 50, 70, 100

Standards: ASTM D-4186, ASTM D-2435, ASTM D-3877, BS 1377-6, CEN ISO/TS 17892-5

Tests that can be Performed:Stepped loading, constant rate of loading (CRL), constant rate of strain (CRS) and hydraulic gradient controlled tests.

Upgrade Options:Radial drainage, UNSAT (High air entry stone bonded into a specially modified base) and bender elements. The GDS consolidation system can become a GDS stress path triaxial testing system by changing the test cell, adding a further 200cc pressure/volume controller and software.

Overview: The GDS Consolidation Testing System (GDSCTS) is a state-of-the-art, fully-automated consolidation testing system designed for soil.

The system is based on the Rowe and Barden type consolidation cell using GDS pressure/volume controllers from the Enterprise, Standard, or Advanced range. Two of these pressure controllers link to the computer, one for axial stress & displacement control and one for setting back pressure.

Consolidation Testing System (Rowe Type) (GDSCTS)


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Stress increments applied gradually: The advantage of this method is that the time required to complete a consolidation test can be reduced significantly.

Controlled back pressure (water) is applied to the sample and drainage is allowed through the base of the apparatus:

Allows excess pore pressure to be monitored so tests can run at maximum speed and hence increase specimen throughput.

Run the entire test from start to finish: More efficient testing as no waiting for user inputs.

Interchangeable range submersible loadcell:

Enables the user to run tests on soils of different stiffness and match the load transducers accordingly, giving greater accuracy of results and seal friction does not effect load readings.

Construction material: Anodised aluminium with perspex outer cell wall for long life.

Integral cutter / sample ring: Disturbance on samples is reduced by having a cutting edge integrated into the sample confinement ring.

Tests that can be Performed:Constant rate of loading (CRL), constant rate of strain (CRS) and stepped loading.

Upgrade Options:

20MPa version and bender elements.


Load Range (kN): Low Pressure: 50High Pressure: 100

Pressure Range (MPa): Low Pressure: up to 1High Pressure: up to 20

Sample Sizes (mm): Low Pressure: 38, 50, 70, 100, 150 - 500High Pressure: 38, 50

Standards: ASTM D-4186, ASTM D-2435, ASTM D-3877, CEN ISO/TS 17892-5

Constant Rate of Strain Cell (GDSCRS)

Overview: The GDS Constant Rate of Strain Consolidation cell (GDSCRS) is designed primarily for advanced commercial testing laboratories who want to reduce the time required to complete a consolidation test. The cell fits in a load frame in place of a triaxial cell.

The load frame based one dimensional consolidation cell is capable of applying back pressure and measuring pore pressures up to 1MPa (low pressure version) or 20MPa (high pressure version).




Axial Force Accuracy: 0.1%FROAxial Force Resolution: 0.001kNDisplacement Accuracy: 0.1% - dependant on selected transducerDisplacement Resolution: 0.0003mm - dependant on selected transducerLoad Range (kN): Max Load 10Power: 110 to 240 AC Volt Input, 60 WattsSample Sizes (mm): 38, 50, 63.50, 71.40, 75, 100, 101.6, 112.80

Standards: AASHTO T-216, ASTM D-2435, ASTM D-3877, ASTM D-2435M, BS1377/5, CEN ISO/TS 17892-5, EN ISO/TS 17892/5, JGS 0411, JGS 0412

Tests that can be Performed:Constant rate of loading (CRL), constant rate of strain (CRS) and stepped loading.

Upgrade Options:

Oedometer module – Automated testing (step loading) and data acquisition. An external displacement transducer can be added to increases the accuracy of strain measurements. With the addition of an RFM the device can measure and control from an additional transducer, i.e. axial displacement or pore pressure. The GDSAOS can be arranged in greater numbers connected to a single PC or to multiple PCs.


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: (increasing sample throughput)

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.

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 data logger and transducers as many data loggers, even those from other manufacturers, are compatible with the GDSLAB software.

Automatic Oedometer System (GDSAOS)

Overview: 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 of a hanging weight oedometer.


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Overview: The Enterprise Level Pressure/Volume Controller (ELDPC) is a general-purpose water pressure source and volume change gauge for the precise regulation and measurement of fluid pressure and volume change.

The enterprise level controller is aimed at commercial testing and is available in one configuration, 1MPa pressure, 200cc volume.

Enterprise Pressure/Volume Controller (ELDPC)

Overview: The Standard Level Pressure/Volume Controller (STDDPC) is a general-purpose water pressure source and volume change gauge. Aimed at medium pressure commercial testing (≤4MPa), undergraduate teaching and research, the standard controller is the mid level controller from GDS.

Available in 200cc only, but with pressure ranges from 1MPa to 4MPa (the standard range is 3MPa).

Standard Pressure/Volume Controller(STDDPC)

Overview: The Advanced Pressure/Volume Controller (ADVDPC) has the highest precision for the regulation and measurement of fluid pressure and volume change. The advanced version offers the highest level of accuracy, resolution and control and is the defacto standard for research devices. The ADVDPC may be used with water, oil or air. Available in pressure ranges from 100kPa to 4000kPa and a volumetric capacity of 200cc, or up to 2000kPa with a volumetric capacity of 1000cc.

Advanced Pressure/Volume Controller (ADVDPC)

Overview: Based on the advanced controllers, the GDS High Pressure/Volume Controllers are a general purpose water pressure source and volume change gauge for the precise regulation and measurement of fluid pressure and volume change at much greater pressures. The advanced version offers the highest level of accuracy, resolution and control and is the defacto standard for research devices. The high pressure range of controllers are available in pressure ranges from 8MPa to 150MPa and a volumetric capacity of 200cc. High pressure controllers can be used with water or oil.

High Pressure/Volume Controllers 8MPa to 150MPa (HPDPC)



Key Features of GDS Controllers: Benefits to the User:Does not require a supply of compressed air to function: GDS pressure controllers do not rely on lab air supplies.

Controlled with or without a PC:The GDS pressure controllers can be controlled directly from a computer using the USB 2.0 interface and GDSLAB or with the Smart Keypad (optional for ELDPC) the controller can be configured as a completely stand-alone device.

Accurate measurement: Pressure is measured by an integral pressure transducer. Volume change is measured by counting the steps of the incremental motor.

GDS controllers automatically protect themselves from pressure and volume over-ranges:

All GDS pressure controllers are self-protecting and can also be programmed to protect any attached equipment.

Controllers are an ideal back-pressure source:

Allowing the measurement of change in volume of the test specimen with no requirement for a separate volume change device.

Controllers can be used with different media:

The ELDPC, STDDPC and ADVDPC run using water or oil and GDS have an ADVDPC (1000cc) specifically for use with Air.

Manufactured in the UK: All GDS Pressure Controllers are designed, machined and assembled to the highest quality standards and materials in the UK.

Compliant: All GDS Digital Pressure Controllers are fully RoHS and CE Compliant.

Upgrade Options: Optional: Digital Remote Feedback Module (Digi RFM) - for STDDPC and ADVDPC Controllers

Normally, the feedback to the main control circuit board comes from the internal pressure transducer. However, this input could come from a different source, such as a remote transducer. GDS has developed this into an elegantly engineered enhancement, which is the Remote Feedback Module (RFM). The RFM enables the output of an external transducer to be measured and displayed by the controller. It also enables the controller to be controlled from the feedback of the external transducer. The internal pressure transducer and the external transducer readings are displayed and transmitted over the computer interface.

Benefits of the Digi RFM include:-

• Precision when regulating from the external transducer, as it can be positioned closer to the experiment.• Can increase the accuracy of the application by choosing a transducer closer to the range of the experiment.• Can be used with wet-wet differential pressure transducer to increase the accuracy and measurement, e.g. For precise

control between back pressure and cell pressure for accurate measurement and control of very small effective stresses.

Legacy BoardMany customers have been using GDS advanced pressure controllers for many years with their own software. The software interface has remained unchanged since 1980. A legacy interface board is available to allow new USB based controllers to operate on RS232 with the same PC interfaces as advanced controllers sold between 1980 and 2013, to avoid changing existing software.


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Features ELDPC STDDPC v2 ADVDPC / HPDPC

Accuracy of measurement: 0.25% FRO 0.15% FRO Better than 0.1% FRO

Pressure range (MPa): 1 1, 2, 3, 4 0.1, 0.2, 0.4, 0.8, 1, 2, 4, 8, 16, 20, 32, 64, 100, 128 and 150

Pressure Display Readable to: 1kPa0.1kPa on 1MPa range, 1kPa on 2MPa and above ranges.

0.1kPa up to 64MPa range, 0.8kPa for 64MPa and above ranges

Resolution of logging via software: 1kPa (1000 device)

0.1kPa on 1MPa version, 1kPa on 2MPa and above

0.1kPa up to 4MPa range, 1kPa up to 150MPa

Pressure calibration: 2 point calibration (FRO) 2 point calibration (FRO) Multipoint calibration, certified with table.

Resolution (volume): 1mm3 (0.001 cc) 1mm3 (0.001 cc) 0.5mm3

Volumetric range: 200cc 200cc 200cc or 1000cc (2 MPa only)

Ball screw: Rolled – lead error 100 µm in 330mm

Rolled – lead error 100 µm in 330mm

Ground – lead error <25 μm in 330mm

Gearbox: Class C Class C Class A, precision

Interface options: USB USB USB or RS232

Material and finish of pressure cylinder: Brass, painted Brass, painted

Brass, bright nickel plated and polished stainless steel

Size (mm): 500 x 100 x 125 620 x 100 x 140

860 x 230 x 220 (2MPa)860 x 230 x 230 (1000cc)860 x 230 x 260 (32MPa)860 x 230 x 330 (64MPa)

Weight (kg): 5.5 (empty) 10.2 (empty) 20-250

Electrical supply(universal):

100-240V AC, 50-60Hz, 0.7A. Max Consumption: 20W. Typical Consumption: <12W

100-240V~1.6A MAX, 50-60Hz

85 VAC to 260 VAC;47 – 60 Hz

The table below is a controller comparison chart for the Enterprise (ELDPC), Standard (STDDPC), and Advanced (ADVDPC/HPDPC) level pressure / volume controllers.



Key Features: Benefits to the User:Built in pressure transducer measures the air pressure: The result is a compact, neat, self-contained unit.

Pressure measurement from the system is sent via a separate datalogger to the PC:

10V output signal can be connected to most existing data loggers.

Automated control:The automated control of the pneumatic controller allows the user to run and log a series of tests without having to be continually monitoring or manually adjusting the pressure.

The pneumatic controller is available as either a 1 or 2 channel controller:

Two channel units are a very efficient way of replacing existing cell and back pressure manual regulators.

Calibration certificate: The pneumatic controller is calibrated at GDS, and is supplied with a certificate. No user adjustment to the hardware is necessary.

Media that can be used with pneumatic controllers:

• Nitrogen.• Air.• Argon.• Helium.• Most inert gases.


Computer Interface: RS232Dimensions (mm): 600 x 230 x 100Pressure Range (MPa): 1, 2 or 3Weight Approx (kg): 6

Overview: The GDS Pneumatic Pressure Controller (GDSPPC) is an economical source of computer controlled regulated air pressure. The controller regulates an external pressure source of compressed air from a compressor or compressed air cylinder to provide a controlled output pressure. The control of the valves is via the serial bus (RS232) from the PC and software.

The pneumatic controller is a cost effective route for upgrading manual regulator systems to automated systems.The GDSPPC is available with one or two channels.

Pneumatic Pressure Controller (GDSPPC)


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Primary (Master) and Secondary (Slave) Controllers:The GDSIVC system works by connecting two GDS pressure controllers in parallel, automatically switching between them when they run out of volume. One controller is designated as the primary controller and is used as the main pressure/volume source. While acting as the pressure and volume source this controller is called the master controller.

Careful switching sequencing in the software ensures that valves are energized for the minimum period necessary, and remain unenergised for most of the test because soleniod valves generate heat when energised that could affect the downstream experiment. The configuration also ensures any pressure calibration differences between the primary and the secondary controller are compensated for.

Key Features: Benefits to the User:Continuous volume flow: Allows long term (laminar flow) permeability tests to be carried out.

Secondary controller follows primary:The second controller will match the output pressure of the primary controller, this feature allows for minimum time switching. Empty controllers are automatically refilled from a reservoir (not supplied).

The GDSIVC system automatically switches between controllers when they run out of volume:

Infinite Volume!

Controller flexibility: Can be used with all types of GDS controller (ELDPC, STDDPC or ADVDPC).


Dimensions (mm): Panel: 440 x 260 x 100, Control Box: 440 x 260 x 50 Pressure Range (MPa): 3, options available for higher pressures

Overview: The GDS Infinite Volume Controller (GDSIVC) is designed to remove the constraint of volume capacity such that a test can continuously flow fluid under pressure or volume control. By connecting two GDS pressure/volume controllers in parallel, the GDSIVC system automatically switches between them when they run out of volume, thus providing a seamless supply of pressure with unlimited volume capacity.

The GDSIVC can be used with any two pressure controllers from the GDS range, i.e. Advanced, Standard or Enterprise.

Infinite Volume Controller (GDSIVC)

Primary controller in control (Master)

Secondary controller tracking primary controller pressure (slave)

Primary controller runs out of volume

Primary controller closed to experiment and opened to reservoir to refill

Secondary controller takes over as the master temporarily while the primary controller is refilling.

When primary controller has refilled, it will resume control of the experiment by once again becoming the master controller.

Secondary controller will refill as necessary, return to its mid point and pre-pressurise.

With the secondary controller already pre-pressurised, both the primary and secondary controller are put on hold volume and both opened to the experiment to check any calibration offset between the two controllers at pressure. The primary is considered the ‘correct’ controller, and so any offset found will be applied naturally to the target pressure sent to the secondary controller. This ensures smooth volume hand over.



Key Features: Benefits to the User:USB interface: Allows the system to be swapped to any PC in the lab with a USB interface.Titanium element inserts: Reduces the weight of the top-cap.

Utilising existing products: Pedestals and top-caps can be made for other manufacturers cells as well as GDS cells.

The GDS Bender elements are bonded into a standard insert:

This method of manufacture has 2 advantages, it makes the bender element insert a modular device that can then be easily fitted into a suitably modified pedestal/top-cap. Should an element fail, it is simple and quick to replace the complete insert.

2 Mega Samples/Second Data Acquisition:

High speed data acquisition is essential as the sample interval provides the resolution for determining wave speeds.

Elements are manufactured to allow S and P wave testing to be performed:

Determining S & P wave velocities allows more specimen parameters to be determined.

Vertical and horizontal elements are available as standard: Specimen anisotropy can be studied.


Computer Interface: USB Data Acquisition Speed: 2MHzElement type: Single element S and P wave.

GDS Bender Element Analysis Tool:The subjectivity and lack of satisfactory standards for interpreting shear wave travel times across the industry from bender element test data, has led GDS to develop a bender elements analysis tool. The tool allows the rapid, automated analysis of bender element tests to objectively estimate the shear wave travel time. The analysis tool is available to download from GDS’ website. The aim is to share the software with the geotechnical community and help the progression towards accepted standards for these tests.

Tests that can be Performed:Gmax, maximum shear modulus and S & P wave velocities in vertical and horizontal directions.

Upgrade Options:Pedestals for unsaturated testing and bender elements (i.e. with bonded high air entry porous disc) & Horizontal bender elements.

Overview: The GDS Bender Element System (GDSBES) enables measurement of the maximum shear modulus of a soil at small strains.

The GDS system is unique in that it is a turn-key system that has been designed to make bender element testing reliable and easy to perform. The GDSBES system can be added as an option to most GDS systems, as well as systems from other manufacturers. To date GDS have installed bender elements in triaxial, consolidation, simple shear, resonant column, core holders and many other systems manufactured by GDS and equipment from other manufacturers.

Bender Element System (GDSBES)


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Key Features: Benefits to the User:Axial and radial deformation measured directly on the triaxial test specimen: Removes bedding errors or “end effects”.

Light compact semiconductor chip:The Hall Effect semiconductor chip is very light, has compact assembly and is compensated against changes in ambient temperature and changes in DC voltage supply.

Accurate determination of soil stiffness:

True soil strains can be masked by deflections which originate in the compliances of the loading system and load measuring system. Such equipment compliance errors add to a variety of sample bedding effects to give a poor definition of the stress strain behaviour of the material under test, particularly over the small strain range.

Small strain measurement:Recent work has demonstrated that soils can be equally as brittle as rocks and that an understanding of their behaviour at levels of shear strain below 0.05% is very important.

Measurement is taken in the middle third of the sample which is less restrained than the end zones:

Therefore, it is highly desirable that radial and axial deformations are measured locally in this region if realistic deformation moduli are to be found.


Displacement Range: +/-3.0mmPressure Range: Up to 1700kPaResolution of Measurement: <0.1μmSample Sizes (mm): 38, 50, 70, 76, 100,150, custom

Accuracy: +/-0.2% FRO over 4mm range, +/-0.3% FRO over 5mm range and +/- 0.4% FRO over 6mm range

Weight Approx (kg):Radial caliper weight: 38mm caliper = 24g, 70mm caliper = 46g. Axial apparatus weight: (1 off) = 16g. Transducer weight: (1 off encapsulated HE Chip) = 5g

Hall Effect Local Strain Transducers(GDSHE)Overview: The GDS Hall Effect Local Strain Transducers (GDSHE) provide on sample small strain measurements of axial and radial strains for triaxial testing. GDSHE are very light and easy to handle, therefore can be mounted to the sample for small strain measurement with minimal disturbance to the sample.

Small strain stiffness values are becoming more commonly required by consultants due to the parameters required for FE models. It has been recognised for many years that small strain measurement is more representative to the operational strain, and that the small strain stiffness curve is required for any advanced modelling of the soil.



Key Features: Benefits to the User:Axial and radial deformation measured directly on the triaxial test specimen: Removes bedding errors or “end effects”.

Inherently robust LVDT’s as they have no physical contact across the sensing element:

Zero wear ensuring longer life and lower friction effects.

Submersible low pressure version: Water version can be used up to 3500kPa.

Vented high pressure version: High pressure version for use in non-conducting oil up to 200MPa (Pressure relieved).

Temperature limits -20°C to 60°C: Suitable to use with Environmental Triaxial Testing equipment, see page 9 for more information). Higher temperature versions available.

Measurement is taken in the middle third of the sample which is less restrained than the end zones:

Therefore, it is highly desirable that radial and axial deformations are measured locally in this region if realistic deformation moduli are to be found.

Through bore configurations: Allows test to continue after the LVDT has passed its measurement range.Radial sprung aluminium-bronze hinge for no backlash and low friction: The transducers measure sample effects not those of the measuring calipers.


Displacement Range: +/- 2.5mm or +/-5.0mmData Acquisition: 16 BitResolution of Volume Measurement: +/- 2.5mm = <0.1μm, +/- 5.0mm = <0.2μmSample Sizes (mm): 50, 70, 76, 100, 150, up to 300 as standardVolume Accuracy: 0.1% FRO

Weight Approx (kg): Radial caliper weight: (based on a nominal 70mm caliper) = 74g : Axial apparatus weight: (1 off) = 26g : Transducer weight: (1 off LVDT) = 20g

Overview: The GDS Local Strain Transducers (LVDT) provide on-sample small strain measurements of axial and radial strain for triaxial testing. Accurate determination of soil stiffness is difficult to achieve in routine laboratory testing. Conventionally, stiffness of a triaxial test specimen is based on external measurements of displacement which, include a number of extraneous movements.

True soil strains can be masked by deflections which originate in the compliances of the loading system and load measuring system. Such equipment compliance errors add to a variety of sample bedding effects to give a poor definition of the stress-strain behaviour of the material under test, particularly over the small strain range.

LVDT Local Strain Transducers (LVDT)


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Can be used in a multitude of ground conditions:

Typically used in site investigations for foundation engineering design and settlement prediction. The SASW is also suited for the rapid sub-grade evaluation for roads, tracks and runways.

Fast Fourier Transform (FFT):

The system performs an on-line Fast Fourier Transform (FFT) on the acquired data with automatic stacking and trigger arming allowing for as many as 15 separate records per minute to be acquired for a single test. The stacked data can be manually or automatically ‘picked’ to create an on-line stiffness v depth plot.

Portable design: The SASW runs continuously for up to 8 hours with user supplied 12V battery and is supplied with a padded transport case with built in laptop weather hood.

Set up in 5 minutes, tests performed in 10: Providing stiffness v depth results immediately in field.

Non-invasive testing: No samples are required to be obtained from the test site.

Tests that can be Performed:Non invasive shear wave velocity and shear modulus profiling.

Upgrade Options:Can be upgraded to a CSWS system (Continuous Surface Wave System) with the addition of an amplifier, a ground vibrator and the CSWS software.


Computer Interface: USB ConnectionData Acquisition: 16 BitDimensions (mm): 400 x 380 x 150Power: 12-24V DCWeight Approx (kg): 5.5 + Source + Battery

Overview: SASW provides a portable, quick and nondestructive insitu ground stiffness profiling tool. Typically a test can be carried out in under 15 minutes with initial results available whilst still on site.

Spectral Analysis of Surface Waves (SASW)

Battery or Generator

Sledge Hammer Geophones

Control UnitUSBConnector




Provides depth profile up to 30m: Provides on-line shear modulus with depth profile to depths of up to 30m depending on the type of soil or rock

Rapid results through non-invasive test methods:

Enables rapid assessment of ground variability across a site in terms of stiffness via a non-invasive test.

Insitu nondestructive testing: Provides stiffness parameters for ground that is difficult or impossible to sample in a representative manner, e.g. granular soils and highly fractured rock.

Quick test: Verifies soil improvement, from dynamic compaction, vibrofloatation and classic consolidation.

Enables the measurement of Gmax: Enables the measurement of Gmax which can provide a valuable benchmark for stiffness investigations in soils and sample quality.

Automated test software:

The user enters the required test frequencies and the software runs the complete test automatically. Output can be imported directly into Microsoft® Excel. Data output includes time domain, frequency domain (magnitude and phase), coherence and stiffness v depth using the Lambda/3 method.

Lightweight & portable design:Rugged, robust, smaller and lighter control unit (version III control unit weighs only 5.5kg) and is supplied with a padded transport case with built in laptop weather hood.


Computer Interface: USB ConnectionData Acquisition: 16 BitDimensions (mm): Unit: 400 x 380 x 150 Ground Vibrator: 450 x 350 x 180Power: 12-24V DCWeight Approx (kg): Ground Vibrator: 70, Control Unit: 5.5

Tests that can be Performed:Non invasive shear wave velocity and shear modulus testing.

Upgrade Options:Standard system for 2-6 geophones, upgradeable to a maximum of 12. Can be used as a Spectral Analysis of Surface Waves (SASW) test system using an impact source.

Overview: CSWS provides the user with the ability to generate a wider and more controlled frequency range for carrying out surface wave testing. This will usually achieve greater penetration depths and resolution than the SASW.

Continuous Surface Wave System (CSWS)PowerGenerator

Geophones

Control Unit USBConnector

Amplifier

Vibrator

GDS InstrumentsUnit 32 Murrell Green Business Park,London Road, Hook,Hampshire, UK, RG27 9GR.Tel: +44 (0)1256 382450Fax: +44 (0)1256 382451Email: [email protected]: www.gdsinstruments.com

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