Experimental Investigation on the Mechanical Behavior of a New Three-Dimensional Pressure Transducer

Accurate measurements of in situ stress in deep soft rocks are needed to design the tunnel support system and to evaluate the stress redistribution process. Due to the difficulty and weakness of current methods in deep soft rock stress measurement, a new one, rheological stress recovery method to determine the three-dimensional stress tensor is proposed. It is supposed that rock stresses will recover gradually with time and can be measured by embedding transducers into the borehole. According to this method, an original three-dimensional pressure transducer to measure rock stresses is designed and manufactured. In order to investigate the accuracy of the measurement, calibration test and model test have been performed. Both uniaxial and tri-axial calibration tests are conducted to evaluate the transducer performance. For model test, the cement mortar was used to simulate the effect of the surrounding materials. This test considered different rock strengths as well as different types of loading. The results indicate that this transducer is good for stress measurement.