Abstract: A substantial number of geotechnical projects, including massive concrete structures, necessitate distributed crack monitoring, which can be accomplished through the implementation of fiber optic monitoring technology. In order to investigate the coupling performance of distributed optical fiber and mass concrete, a multifaceted approach was employed, encompassing theoretical analysis, numerical simulation, and indoor experimental studies. These investigations were applied to a mass concrete raft slab foundation. The findings indicate that the strain transfer model of optical fiber under compression, established based on shear-slip theory, can achieve precise quantification of the strain transfer efficiency of optical fiber. Numerical simulations are employed to verify the accuracy and reliability of the model. The coupling performance between optical fiber and concrete under different arrangement methods is studied by using different optical fiber arrangement methods for reinforced concrete beams and conducting three-point graded loading tests. The results show that the optical fiber laid along the vertical direction of the reinforcement has a better coupling effect with the concrete. The on-site fiber optic monitoring of mass concrete raft foundation demonstrates the efficacy of fiber optic sensors in coupling with the mass concrete structure, facilitating precise strain evolution process monitoring and key area law determination post-casting. The research findings establish a theoretical foundation and essential technology for distributed fiber optic technology in geotechnical engineering structure deformation monitoring.

Key words: distributed optical fiber sensing technology, coupling performance, strain transfer mechanism, strain monitoring of massive concrete raft foundation