MTS Model 286-30 Pore Pressure Intensifier - Manual (Page 35)

Operating Procedures
286.30 Pressure Intensifier Operation 35
Filling the Specimen’s Pores with Pore Fluid
This procedure will cause pore fluid to flow into (and purge air from) the lines
between the PPI’s pressure intensifier and the triaxial cell, the triaxial cell, the
specimen’s pores, and the lines between the triaxial cell and the PPI’s Pore Fluid
Output valve. (Pore fluid will be allowed to flow through the PPI’s Pore Fluid
Output valve until a very small flow of pore fluid is seen entering the PPI’s
reservoir.)
Note During this procedure, the PPI will be operated under closed-loop control
in the pressure control mode. Because of the variety of electronic
controller equipment in use, explicit instructions cannot be provided for
some steps. Refer to the system operation manual.
Preliminary steps or
conditions:
• The pressure intensifier is full of pore fluid and the piston is (approximately)
at the 10% displacement position, as established in the preceding procedure.
• The Intensifier Fill, Reservoir Return and Reservoir Drain/Fill valves
are all closed.
• A jacketed specimen is installed in the triaxial cell and the cell is sealed for
operation.
• Hydraulic power (from the external hydraulic power supply) is not applied
to the PPI at this time.
Pore fluid pressure should not be higher than confining fluid pressure.
If pore fluid pressure is higher than confining fluid pressure, the jacket on
the specimen will rupture.
Always maintain confining fluid pressure at a higher level than pore fluid pressure.
(Refer to the manual for the Confining Pressure Intensifier for instructions on
controlling confining pressure.)
CAUTION