Abstract：In order to detect the deformation and development of deep rock strata，a FBG-GFRP-cement mortar- unconsolidated soil layer strain transfer system is formed；based on the theoretical analysis results of the strain transferring of FBG sensor，the effects of the mechanical parameters of optical fiber，middle layer and host material on the strain transfer rate are analyzed；and the FBG sensor used for rock deformation monitoring and the borehole parameters are designed，which provides a basis for engineering application. The results show that，in the monitoring of rock strata，the diameter of the borehole is adopted to be about 100 mm，the critical length of FBG sensor used in this system is 149.23 mm. This system is then applied to the settlement monitoring of Quaternary system unconsolidated soil layer in Jining coal mine No.3，it is shown that FBG sensors can be used to monitor strain change of unconsolidated layer.
