(1. Department of Civil and Structural Engineering，The Hong Kong Polytechnic University，Hong Kong，China； 2. Shenzhen Graduate School，Harbin Institute of Technology，Shenzhen，Guangdong 518055，China)
Abstract：A new type of in-place inclinometer based on fiber Bragg grating(FBG) sensing technology and the related analysis method are presented. Based on the linear relationship between the wavelength change of FBG and strain，the strains at different measuring points on the new in-place inclinometers are obtained. Using the classical beam bending equation and finite difference method，the displacements of the inclinometer can be calculated. This new type of in-place inclinometer overcomes certain disadvantages of the conventional in-place inclinometer，such as low accuracy，poor durability，and complex operation. Laboratory calibration results verify the reliability of the new in-place inclinometer and its analysis method. For a cut slope along the Panzhihua—Tianfangcun highway，three new FBG in-place inclinometers were placed in three vertical boreholes in the same cross-section of the slope, ensuring that the inclinometers passed through the potential slip surface. Then the field monitoring started. Monitoring data derived from the inclinometers are collected and analyzed. An optimal model is adopted to calculate the position of the potential slip surface and the factor of safety of the slope，which is well compared with the results obtained from Bishop¢s method. It is shown that the method presented provides a new and reliable approach for assessment of slope stability based on slope monitoring data.
