USP

Unsaturated Stress Path Triaxial Cell

This advanced system has been developed to test soil in natural conditions where saturation is not complete.
The system we have developed in cooperation with the Department of Geotechnical Engineering of the University of Naples is based on an improved Bishop & Wesley type triaxial cell.
All the controls and data logging are built into the system providing complete test control. The acquired data are presented, printed and saved in a file while will be easy to switch from stress to strain control thanks to a dual axial control.
The system comes as a complete, self-contained unit with all of the equipment required to perform triaxial stress/strain path tests. The control box size is 800 mm (h) 500 mm (w) 500 mm (d).

The improvements to the standard triaxial cells are:

A modified area of the lower bellofram in order to perform the first part of the shearing stage under stress controlled condition with a standard 1000 kPa pressure supply.
Longer stroke of piston to increase the maximum axial displacement and the axial compliance eliminating the need for a feed screw.

The system includes:

An improved Bishop & Wesley triaxial cell for 70 mm samples (optional 38 mm, 50 mm, and 85 mm) including pedestals, interchangeable stones, top cap
A series of transducers including submersible load cells, pressure sensors, an axial strain LVDT, water content set-up using a differential pressure transducer and a volume gauge based on a second differential pressure transducer
A stepping motor driven screw pump for the axial strain control
An electropneumatic converter for axial stress control via a included air-water interface
An electropneumatic converter driving the cell pressure (radial load) by means of included air-water interface
An electropneumatic converter to control the sample water pore pressure
An electropneumatic converter to control the sample air pore pressure
A control box including all the electronic, pneumatic and hydraulic parts, including the pressure gauges and the valves to accomplish the test and check the operation
A complete PC with data acquisition and control boards
An open source software able to control the four electropneumatic converters and the screw pump and to acquire all sensors.

The system has been designed for advanced research and test work providing space for local strain transducers.