Abstract:

 Ground collapse accidents pose a large threat to the safety of cities due to their suddenness. It is very important to understand the development process of internal deformation of collapsed soil for prediction of ground collapse. In this study, based on the optical frequency domain reflectometry (OFDR) and particle image velocimetry (PIV) technologies, ground collapse model test was performed, and the tempo-spatial distributions of ground settlement in the collapsed area were investigated. The influence of anchoring methods of distributed strain sensing cables on the fiber optic monitoring results was explored. The results show that the fiber optic strain measurements reflect the deformation state of the overlying soil in different collapse stages and reveal the internal strain evolution mechanism of the ground soil. The coupling effect of the cable-soil interface is effectively enhanced by adding circular micro-anchor plates and is better with the increase of the diameter of the anchoring circulars at a certain burial depth. The research results show that the distributed strain sensing technology has good applicability in monitoring ground collapse and can provide a powerful tool for mitigating such geohazards.

Key words: fiber optic sensor, ground collapse, settlement monitoring, interface behavior, model test