Abstract: Land subsidence as a common geological hazard poses a great threat to urban development. Effective monitoring of vertical
deformation process of soil layers is an important task for land subsidence prevention and control. In this paper, Brillouin Optical
Frequency Domain Analysis (BOFDA) technology is used to monitor the vertical deformation of sand-clay layers in draining-recharging
cycles by using an indoor land subsidence model. Moreover, a compression test is used to analyze the vertical deformation of the soil.
The results show that the clay layer is the main deformation layer. In the draining-recharging cycles, the soil also experiences
compression-rebound cycles. In addition, BOFDA technology can effectively capture the vertical deformation of sand-clay layers in
draining-recharging cycles and monitor in real-time the soil vertical deformation in the process of land subsidence development. The
research results provide some reference for the effective prevention and control of land subsidence.

Key words: land subsidence, distributed monitoring, BOFDA, physical model, vertical deformation