Model test research of wave-induced submarine landslide based on Fibre Bragg Grating sensing technology

Submarine landslides are common marine disasters that pose significant threats to human safety. However, there is no established method for monitoring submarine landslides. To effectively prevent and control such disasters, this study conducted a series of investigations based on the Zhujiajian Landslide. Based on optical fibre sensing and numerical simulation technology, this study proposed a sensor optimisation method for a submarine landslide simulation experiment. Three types of fibre-optic sensors with high sensitivity and corrosion resistance were developed, and the designed sensors have broad application prospects for monitoring complex environments. A wavelength-division multiplexing sensor-networking method for submarine landslide simulation tests was proposed. A simulation test of a submarine landslide under wave action was conducted to verify the practicability of the optical fibre monitoring system, and experimental data were collected. The variation characteristics of the seepage pressure, displacement, and velocity fields were studied. The results showed that submarine landslides are the products of liquefaction and shear failures. Continuous wave action causes the accumulation of pore water pressure in the soil mass inside the slope, which leads to a decrease in the shear strength. The shearing action of waves is the driving force for submarine landslides. When a submarine landslide occurred, both displacement and pore water pressure showed a sudden change, but the sudden change in pore water pressure occurred approximately 5 s earlier than that of the sudden change in displacement. A 50:1 on-site prototype was obtained by converting the time similarity scale, and the on-site pore water pressure mutation time was approximately 30s earlier than the submarine landslide occurrence time. Therefore, when conducting on-site submarine landslide monitoring, pore water pressure can be prioritised as an evaluation index for the stability of submarine slopes. The research results provide effective technical support for the prevention and control of submarine landslides and have reference significance and application value for similar projects.