Surface pasting methods and analyses of strain transfer in rock deformation tests using FBG

The key technology and theory of rock deformation tests using fiber Bragg grating (FBG) sensing are studied, and the surface pasting method to be applied in uniaxial compression experiments is proposed. A strain transfer model of fiber sticking on surface is established, and the strain transfer coefficient is obtained by deducing. On such a theoretical basis, a comparative experiment in MTS is conducted, and the tests are along the axial and radial directions. The results indicate that the converted axial strain of FBG accords with that of MTS, and the relative error rate is only 2.8%. The effect of the ring strain tests is better than that of MTS radial strain gauge, and the two methods are all obviously better than the electrical strain gauges at the same position. This validates the proposed transfer model of surface pasting and also indicates that this method can be used in rock uniaxial compression experiments. Compared with the traditional tests, FBG has unexampled advantages. It has important meaning to increase the test level of rock deformation and to achieve long-term and on-line monitoring in rock engineering.