Shaping the Future of Underground Monitoring with Carbon-fiber Self-sensing Smart Materials

Amid global warming, energy shortages, and the increasing frequency of extreme climate events, the development of sustainable and intelligent underground infrastructure has become a critical strategy for addressing major societal challenges. Unlike surface structures, underground infrastructures are subjected to high stress, dynamic loading, and groundwater erosion. Under such conditions, traditional cement-based materials are prone to strength degradation, fatigue damage, and permeability failure, which significantly limits the service life and operational safety of underground constructions. Incorporating short carbon fibers into cement-based materials not only enhances their mechanical strength but also enables real-time monitoring of internal stress, deformation, and damage states through changes in the electrical resistivity of the carbon fiber network. The application of this material in underground engineering leverages its dual functions of structural reinforcement and damage monitoring, realizing the concept of "material as a sensor." However, several challenges remain in the practical application of this material. First, groundwater erosion may affect the stability of the mechanical and damage monitoring performance of carbon fiber composites. Second, the reliability of its damage monitoring performance under long-term high-stress environments has yet to be verified. Additionally, large-scale engineering applications must also consider the economic feasibility of the material. Conducting in-depth research in these areas will vigorously promote the large-scale application of carbon fiber composites in high-stress and water-bearing underground environments, providing key technical support for the long-term safe operation of engineering structures.