Safety of longwall mining with caving in the light of data from monitoring systems

Abstract

Shield supports are usually perceived as devices consisting mainly of mechanical and hydraulic parts, while other apparatus, mainly related to electronics, is often treated as a necessary supplement to the system which ensures its control. However, the development of features closely related to the latest electronic equipment in the mining complexes, mainly connected with measuring and registration possibilities, also allows for more and more frequent use of various types of monitoring. It enables observation of the operation of the mining complex in real time or with a slight time delay. What is more, it also enables signalling the operating states of the shield constituting specific threats or irregularities. The most advanced systems found abroad are equipped with functions analysing changes in specific monitored parameters to develop warnings about possible future threats to allow the operator to react with sufficient time in advance. Developing such a forecast system requires gathering and then analysing a sufficiently large and complete database of measurements and observations. These are primarily associated with various difficulties in operating a shield support, and especially with strictly emergency states, such as rock slides, shield clamping conditions, etc. The developed warning identifiers also depend on the mining and geological situation of the specific mining panel. The monitoring currently used, concerning a part of the mining complex related to the shield support, mainly concerns the pressures in the hydraulic props of the shield and the measure of the shifter advance. It allows determining the position of the section on the longwall panel length. The current instantaneous shield geometry and dimensions of the excavation itself, such as height, setting and inclination, are determined in-situ much less often. The information obtained is often also sent to the surface of the mine. The data from monitoring of shield support operation, through proper development of dependencies and analysis results, can optimize the safety of crew, reduce difficulties in maintaining the roof of longwall excavations and thus have a positive impact on the obtained economic results.