Currently, thousands of former coal mines are abandoned and flooded across Europe. They have to be inspected, in order to detect any warning signs indicating potential instability. However, the traditional inspection methods come up against technical and environmental difficulties: great depth, chemically aggressive waters and other hazards. The main objective of the STAMS project was to develop and test tools to inspect these abandoned mining works.
To overcome the difficulties, two categories of equipment have been developed during this project:
- The first makes it possible to undertake periodic inspections.
A multi-functional periodic monitoring module (MMM), fitted with high precision cameras, an ultrasound module and an anti-collision system has been developed. These instruments were designed to analyse the condition of the shaft lining in turbulent water under high pressure (100 bar). A reference point installation module has also been developed. Installation is possible with the assistance of a remote operating vehicle (ROV), which makes it possible to install reference points to a depth of 1,000 m. These points have been specially designed to withstand the difficult conditions in abandoned shafts. In addition, software has been developed to monitor these instruments and analyse the data and measurements in real time. The functionality of the tools developed has been successfully verified in laboratory conditions and in actual abandoned, flooded shafts in Germany, Spain, Poland and the United Kingdom.
- The second category covers equipment designed to continuously sample the water and gas in the mine environment.
Detailed studies have been conducted on electronic sensors, that do not require connection to an electricity supply. A system of tubes has been designed for the very long term monitoring of hostile environments. Moreover, laboratory tests have been conducted to study the production of gas as an indicator of the deterioration of the lining of the flooded shafts. Coupled digital modelling (HMC) has made it possible to quantify the effect of deterioration of the walls on the local and global instability of the flooded shafts, as a function of the aggression of the water in the flooded shafts.
This equipment has been successfully tested in a number of abandoned shafts in coalfields in Europe (Germany, Spain, Poland and the United Kingdom).
The field of derived applications at other types of abandoned underground works has yet to be explored.