A calibration test on optical fiber sensing device for karst collapse monitoring

In line with the deformation characteristics of the sinkhole collapse, the mechanic relation between the soil body and the sensing fiber is analyzed, the mechanic model of collapse is simplified, and simulation test device is processed and tested. Firstly, the sinkhole formation process is stimulated with the orderly changes under load on the optical fiber. And then, the impact of the changes in sinkhole size on the sensing fiber monitoring is analyzed. The study shows that the key factors affecting the application of the technology include the stress field distribution changes led by overlying loads and hole size change during the formation of the holes, and the difference of responding sensitivity to the stress field change among different optical cables. The calibrated optical fiber sensing device in the study can preferably show the features of the stress field changes during the formation and evolution of the hole, which states that the optical fiber sensing device can be used in monitoring and early warning for karst collapse.