As of October 2, 2022, the Alioth Group, acting in cooperation with DSI-Sandvik Undergound, introduced in the area of the exploited longwalls of the coal mine of the PGG group, a fiber-optic rock mass stress monitoring system based on the unique FORBS (Fiber Optic Rock Bolts System) sensors developed and patented by the Alioth Group (patent application No. P.442438 utility model application W.131019).

Intrinsically safe FORBS sensors have been installed in the longwall roadway arrow in the area of the exploited hard coal longwall at level 500. A grid of FORBS sensors connected by a fiber-optic cable to an analyzer and data recorder allows continuous monitoring of the behavior of rock masses (24H7) with ongoing visualization of measurement data from each anchor on a computer screen for those responsible for the safe operation of the workings.

Those interested in the continuous measurement of rock masses located directly above the longwall arch casing include the rock bump and casing department, the energomechanical department, the geological department with the mine director at the head.

The fiber-optic measurement system of the behavior of rock masses based on FORBS sensors makes it possible to obtain information on geological phenomena occurring at a distance of up to 2.5m from the anchorage point.

This system allows to:

– measurement and visualization of the forces acting on the existing pavement/chamber casing,

– measurement up to the anchor load capacity of 250-300[kN] depending on the type of measuring anchor used,

– indication of the moment of exceeding the elastic limit of the used measuring anchors,

– making a decision on the need to “tighten” the sensitive area.

Thanks to our unique system, mine employees can monitor rock mass movements from the surface level. This results in an unprecedented increase in occupational safety – the mine supervisor can track the behavior of rock masses in the excavation on an ongoing basis, take immediate action related to the withdrawal of workers from areas with exceeded strength parameters of anchor, anchor-arc or arc lining equipped with additional FORBS sensors.

We are pleased that the unrivaled measurement solution we have introduced is likely to contribute to improving the safety of people in sensitive areas of the mine.