Facilities

The NCG geotechnical centrifuge facility is a 50g-Tonne machine capable of creating model acceleration of up to 150g, effectively increasing the model dimension by the same amount.  For safety reasons the machine is housed in a 0.5 m thick concrete chamber and can be used to test plane-strain and axis-symmetric models.  The main features of the centrifuge are:

• 2 m beam radius
• Fibre optic based data acquisition and experimental control system
• Capable of interfacing to 100's of transducers  to record strain, displacement, pressure, acceleration, temperature etc. 
• Automatic in-flight balancing system
• PLC based machine control system and safety interlocks
• Remote image/video capture

The GDS hollow cylinder apparatus can apply a uniquely wide range of stress paths on the test specimen.  The loading systems are computer controlled and strains can be measured directly on the test specimen.  Studies can therefore be made under the following test conditions:

• Plain strain
• Simple shear
• Very small shear strain

In addition, standard and advanced triaxial tests can be carried out in the apparatus on standard solid cylindrical test specimen, including:

• K-zero consolidation and swelling
• Continuous linear stress paths

The GDS Combined Dynamic Cyclic Simple Shear (DCSS) apparatus is a preferred device for research into dynamic soil behavior because of its simplicity and its ability to model many types of field loading conditions that are difficult to achieve with other laboratory  equipment.   The DCSS apparatus allows for a smooth and continuous rotation through 90 degrees of the principal stress directions.  The ability to simulate principle stress rotation is common to many geotechnical problems, including earthquake loading.  The simple shear device allows direct investigation of the shear stress v. shear strain in drained and undrained situations.  In addition, the dynamic cyclic capability  allows investigation of damping ratio and liquefaction.

The GDS High pressure triaxial testing system is used for research into the behavior of stiff soils.  It features the Virtual Infinite Stiffness (VIS) axial loading system.  Samples of up to 100mm diameter can be accommodated with a cell pressure and back pressure of up to 64Mpa and an axial force of up to 100k.

A PC-Controlled Advanced stress path triaxial testing system suitable for testing both sands and clays at two specimen sizes: 50 and 38 mm.

The system uses the proven GDSLAB software and the classic Bishop & Wesley - type 7kN/1700 kPa/38 mm/50 mm Stress Path triaxial cell with an internal submersible load cell.  Based on the GDS advanced pressure controller, having three pressure controllers linked to a computer to the test cell as follows: 

• One for axial stress and axial displacement control
• One for cell pressure control
• One for setting back pressure and measuring volume change

The GDS Large diameter cyclic triaxial testing system is hydraulically actuated with a large diameter triaxial cell suitable for testing samples with large particle sizes such as railway ballast.  The system is capable of both monotonic (static) and dynamic triaxial tests as well as other advanced triaxial tests.

• 100kN Load range
• 0 to 10Hz Load frequency 
• 450mm height 300mm diameter Sample size
• Volume change measurement

Dynamic triaxial testing system is the ultimate triaxial testing system providing PC automation of:

• Independently programmable cyclic control of axial load and radial stress
• Cyclic axial deformation control
• Stress path control to set up datum of cyclic loading
• B check and saturation ramps
• Classic axial compression and extension tests, stress controlled or strain controlled
• Generalized stress path control; mixed drained sand undrained. 
• K-zero consolidation and swelling

The system has the following major features:

• Local measurement of axial and radial strain by Hall Effect transducers
• Independent external measurement of axial deformation via axial motor shaft encoder
• Internal load cell for the measurement of axial load
• Two synchronized self calibrating PC-resident 16 bit data acquisition and control cards
• Pore pressure measured via transducer connected directly to the base pedestal
• Precise control of measured wave form
• Controlling software for a 100% PC compatible using Windows

Mounted on the back of an Isuzu chassis cab, the unit is furnished with a penetrometer system capable of applying 200 kN of down force and 260 kN pullout force.  The power pack includes manifolded hydraulic controls and valving, and a hydraulic  oil reservoir.

All of the equipment gives a total reaction weight of 8 tons.   The unit is equipped with a 10 ton digital electronic cone configured with one through five channel capacity with six channels from which to choose.

• Tip Resistance
• Local Friction
• Pore Pressure
• Temperature
• Inclination
• Seismic
• Resistivity Module can be added

Wholly digital in nature, a fast microprocessor stores not only calibration information but also identification information.  Plug this cone into the system and it will tell the data acquisition system its "name", what channels are installed, each channel capacity, the date of the last calibration and how many meters of work have been performed. 

The on-board Field Computer System has the capacity to accurately log cone penetrometer data from digital electronic cones plus cone profile plotting.

• Large working area 1m2 with adjustable height up to 1.5 m
• Servo-controlled triaxial cell with volumetric measurement
• Multistage triaxial testing software
• Permeability testing under triaxial stress conditions
• Wide range of additional instrumentation
• High speed computer logging

• Large working area 1m3

• Tensile gripping jaws

• Sample lengths up to 600 mm
• Sample diameters up to 100 mm
• Constant load up to 50 tonnes
• Test periods in excess of 20 days

• Cerchar
• Point Load testing
• NCB Cone indentor
• Shore Scleroscope
• Fracture toughness

• Capability to handle 4 tonne blocks
• extremely comprehensive instrumentation package capable of monitoring, logging, and controlling 16 influencing parameters.
• Bit wear evaluation

• Sample Lengths up to 600 mm
• Sample Diameters up to 100 mm
• Constant load up to 50 tonnes
• Test periods in excess of 20 days

• Cerchar
• Point Load testing
• NCB Cone indentor 
• Shore Scleroscope
• Fracture toughness

• 150mm Rock shear box with servo-controlled normal force
• TS 350FD Diamond Saw
• Large Masonary Saw
• Small Diamond Blade Saw
• Jones & Shipman 540 Surface Grinder for Rock Preparation
• Constant Head Permeability Lab Equipment
• Falling Head Permeability Lab Equipment