SP1

Stress-Path Triaxial Cell

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 with on-line graphics. The acquired data are presented, printed and saved in a file while it’s 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 650 mm (h) 450 mm (w) 350 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 conditions 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 38 mm samples with pedestal, top cap, submersible load cell, a pressure sensors, an axial strain LVDT sensor and a dial gauge
A stepping motor driven screw pump for the axial strain control
An electropneumatic converter for axial stress control via an 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 pore pressure via an included volume gauge, a second LVDT sensor, and a second pressure sensor
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 three electropneumatic converters and the screw pump and to acquire all the sensors.

The system has been designed for advanced research and testing, with space for local strain transducers. The cell is provided with a transducer access ring.