In Perm, a sensor has been developed to monitor the condition of soil beneath construction sites.

In the construction of buildings, roads, dams, bridges, and tunnels, geotextiles—a synthetic material—are widely used to reinforce the soil foundation and enhance its load-bearing capacity. Currently, the concept of "smart geotextiles" is being actively researched, which involves embedding specialized sensors within the material for remote monitoring of soil conditions. This innovation could significantly improve the safety of structures by providing early warnings for necessary repairs or potential emergencies. Researchers at PNIUP have developed a fiber-optic system for continuous monitoring of geotextiles. This system reliably detects shifts as small as 0.5 millimeters and is much more cost-effective than the fiber sensors currently used to monitor the condition of buildings and infrastructure.

2024-11-11 10:00:16https://naked-science.ru/article/column/grunta-pod-stroitelnymi-o

The results are presented in the journal "Scientific and Technical Bulletin of Information Technologies, Mechanics, and Optics," 2024. The research was conducted within the framework of the strategic academic leadership program "Priority 2030."

Geotextiles are characterized by low production and replacement costs, compactness, ease of transportation, rapid installation speed, long service life, and low sensitivity to environmental impacts. Additional monitoring of their condition will enhance the safety of construction sites and allow for the prediction of serious emergency situations before they reach a critical state.

“This material is laid in layers with soil. Fiber-optic displacement sensors can be secured to the geotextile, enabling remote monitoring of soil conditions. The system is similar to those used for monitoring railway embankments and reinforcing slopes. Continuous control through fiber optics significantly increases the safety of operating such construction objects,” explains Illarion Nikulin, Professor of General Physics at Perm National Research Polytechnic University and Doctor of Technical Sciences.

Currently, various optical systems are employed to monitor the condition of structures. The most accessible and effective are those based on fiber Bragg gratings. They are used to capture the main parameters of load-bearing construction structures: deformation, vibration, and temperature. However, they are unsuitable for monitoring geotextiles, as soil is more susceptible to changes in environmental conditions. The use of more precise and expensive sensors, compared to telecommunications fibers, is impractical and economically unfeasible.

Scientists from Perm Polytechnic University have developed a fiber-optic system that can be used to monitor the state of geotextiles in granular soils (sand, clay, peat), which are particularly affected by aggressive and unstable environments.

The polytechnic researchers emphasize that the sensor's design must ensure quality measurement of geotextile displacements on the order of one millimeter. This displacement magnitude indicates dangerous deformation of the structure, alerting the need for repair work. Additionally, the system should be easy to install, cost-effective, durable, and environmentally friendly.

“We have implemented a point amplitude fiber-optic displacement sensor made of ABS plastic and Corning SMF-28 optical fiber. It reliably captures displacements of up to 0.5 millimeters. This level of precision is sufficient for monitoring soil conditions. Furthermore, it is significantly cheaper than sensors using fiber Bragg gratings, which enhances its potential,” explains Illarion Nikulin.

The sensitive element of the optical fiber is designed in the form of loops secured within the sensor's housing. During the experiment, it received emissions of varying power from the displacement source, which then propagated through the fiber and reached the photodetector. The signal from there was processed using a program developed on a personal computer.

The fiber-optic system developed by the scientists at Perm Polytechnic University holds promise for high-quality and effective monitoring of geotextile conditions. It enables precise tracking of soil foundation displacements, ensuring the safety of construction structures.