The Geotechnical Laboratory at Virginia Tech has a thermo-mechanical triaxial device built in house. This device is capable of evaluating the effect of temperature change on volume change, pore water pressure generation and shear strength of the soil. The thermo-mechanical triaxial device has two main components, the isothermal equipment and thermo-mechanical components. The isothermal component comprises of conventional triaxial testing apparatus. The thermo-mechanical component, is the part used for applying temperature change to the soil samples. In our approach, the temperature of the sample is increased by using an external heater. A stainless steel water bath and an immersion heater are employed for heating of the samples.
This device can be used to measure the properties of soils subjected to temperatures ranging from 70⁰C to about 150⁰C. Two T-Type Thermocouples are placed in the triaxial cell through the NPT drillings on top plate of the triaxial cell, and sealed using compression fittings. Six additional thermocouples are placed in the steel water bath to ensure the uniformity of the temperature of the water.
A temperature data logger with 8-channels is utilized to record the temperature data collected by the thermocouples. A transmitter is connected to each of the thermocouples to send data from the thermocouple to the multichannel data logger which is later connected to a computer to download the recorded data. The temperature readings are logged and graphed directly by the help of a software.