Hydraulic Load Frames for Rock

Product Code : HLF100, HLF250, HLF1000 & HLF1500

The GDS Hydraulic Loading Frames (HLF) are load frames with a hydraulic dynamic actuator mounted on the cross beam for axial stress/strain cyclic dynamic loading. The HLF frames are available in 100kN, 250kN, 1000kN and 1500kN loads.
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 an advanced capability of dynamic stress path testing. Using large diameter triaxial cells, the HLF enables tests to be performed on large particle sizes such as ballast.


Key features Benefits to the user
The GDS Hydraulic Axial/Radial Loading Frame can be synchronised with the cell pressure (radial stress):
To give a wider range of testing options for the user, the system can provide stable radial stress during testing, removing the requirement for a balanced ram system, with the ability to add an optional dynamic pressure controller to cycle the back/pore pressure during testing.
Advanced transducers available:
A number of optional advanced transducers can be added to the standard system to give measurement of local axial strain and mid-plane pore pressures. Cells can also be updated to incorporate acoustic velocity and acoustic emission transducers.
GDS load frames are extremely stiff and are designed to allow minimum backlash at the point of sample shearing:
Other, less stiff load frames can have adverse effects on the results at the point of specimen failure. At this critical point in the test, due to the compliance in the system under high load, the resulting backlash that is released after failure can affect the results of the test. GDS has overcome this by ensuring the frames are designed to be stiff and ridged at their maximum loads. 
The system is capable of both monotonic (static) and dynamic triaxial tests:
As well as other advanced triaxial tests usually expected from a GDS system, the system is able to perform static testing, allowing for a single system to perform a wider range of tests.
Dynamic control of axial displacement or axial force to 5Hz (frame dependent), sinusoidal waveform:
Direct (dynamic, 5Hz frame dependent) closed loop control of axial displacement, axial force and cell pressure.
Optional dynamic control of radial stress to 5Hz, 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.
Actuators

Hydraulic

Dimensions

Dependent on chosen specification

Displacement Range

100mm

Load Range (kN)

100, 250, 1500kN

Operating Frequency (Hz)

1500kN - 5Hz, (100kN - up to 20Hz, 250kN - up to 20Hz)

  • Triaxial.
  • Additional data acquisition channel.
  • An extensive range of Traixial and Hoek cells are available to a complete triaxial testing solution for rocks.
  • Temperature control (up to 200 Degrees C).