Stabilizing-sensing synergistic geogrid for high-speed railways.

High-speed railway systems demand robust substructure performance and real-time monitoring to ensure operational safety and efficiency. To meet these challenges, we introduce the stabilizing-sensing synergistic geogrid (SMART geogrid), which employs geogrids as soil-stabilizing materials and integrates Fiber Bragg Grating sensors within the geogrid to detect soil variations. Extensive theoretical, numerical, and experimental studies have been conducted on the coupling characteristics between the optical fiber, adhesive, and geogrid in the SMART geogrid. These studies indicate that the SMART geogrid demonstrates superior reliability and testing accuracy. Pull-out and compression tests validate its real-time monitoring capabilities for shear resistance and compressive strain of soil, as well as its ability to enhance soil bearing capacity. The application in full-scale railway tests, enduring 2 million cycles of loading, verifies the SMART geogrid's effectiveness in full life cycle monitoring. Moreover, a Foreign Object Intrusion Detection System built upon the SMART geogrid, combined with machine learning algorithms, achieves a position prediction R² of 0.9999 and 100% classification accuracy, highlighting its potential for intelligent trackbed sensing in high-speed railway applications.