Mining Contract: Real-Time Ground Movement Monitoring for Improved Safety Near Large Excavations Using Distributed Fiber Optic Sensing

Contract # 75D30120C09233
Start Date 9/1/2020
Research Concept

The current state of ground movement monitoring in active underground mines cannot mostly provide real-time, distributed, continuous, and low-cost data acquisition over a large area within a rock mass. This problem can be addressed via advances in the application of distributed optical fiber sensing technology that have the following attributes; the ability to take real-time measurements, to collect data in an active mine environment and survive potential mining-related interference (blasting shock waves, vibration from mining activities, dust, water, corrosion), to measure ground movement across large and inaccessible areas without the need for multiple measurement sites, and to detect ground movement in scales that directly relate to the safety of mine personnel. The main objective of this proposed research is to enhance the safety of miners through real time, distributed ground movement monitoring using distributed optical fiber optic sensor (DOFS) with the goal to further the use of fiber optic-based ground movement monitoring for the mining industry, thus improving the safety of mine personnel.

Contract Status & Impact

This contract is ongoing. For more information on this contract, send a request to mining@cdc.gov.

Optical Fiber Sensors (OFS) have the ability to make continuous strain and temperature measurements in real time. OFS are immune to water damage, corrosion, and high temperatures; however, fiber optic-based ground movement monitoring remains novel to the mining industry. Many case studies have been executed, demonstrating that fiber optics can be used for this application in various configurations (FBG, OTDR, Brillion and Rayleigh scattering) using both purpose built and commercial equipment.

Since the interactions between the OFS, rock mass, and installation packaging are invisible to the observer, data collected from OFS are often difficult to accurately interpret. Due to the wide range of options available for OFS design and installation, a standardized guideline is needed to calibrate the OFS for mining applications. Research will be conducted to close the gap between ground movement in underground mines, and the interpretation of its OFS signal through detailed laboratory scale calibration to critical scenarios common in the underground environment.

Laboratory scale testing will be conducted to analyze the DOFS response in a controlled manner to allow accurate interpretation of field data. This testing will allow the researchers to select the optimal configuration of DOFS installation (bare fiber vs snakelike OFS, grout stiffness, borehole diameter etc.), and will provide necessary calibration data. Full installation and testing will be conducted at the Missouri S&T experimental mine in Rolla, Missouri, to ensure a seamless transition from the development of the DOFS to its deployment at the mine site. This will ensure that the sensor design will be optimized for use in a large-scale setting and that an installation procedure will be developed to place and grout the DOFS in a borehole.

The DOFS will then be installed underground at a mine site near a large excavation with the primary aim of the experiment to measure the ground movement from the rock mass over time. Data collection will take place over the course of one year, after which numerical modeling will be performed using a Multiphysics based simulation platform. The final calibrated model will be used for experimenting different mining layouts, excavation sizes, pillar widths, and other factors that relate to the health and safety of mine personnel.


Page last reviewed: 6/25/2021 Page last updated: 6/23/2021