Analysis of the Causes of Damage to the Stabilisation Actuator of the Cap Piece of the Powered Roof Supports and a Proposal to Reduce the Effects

Abstract

The mining and geological conditions in which coal mining is carried out are highly variable, which results in dynamic rock manifestations. These include rock mass dynamic failure (seismicity), causing dynamic impacts and also quasi-static rock movements that do not result in seismicity but increases pressure in the powered roof support. The paper analyses the resulting damage to the stabilisation actuator of the cap piece. The analysis was carried out based on the research results conducted in real conditions (a mining longwall). This research study aims to obtain information about the pressure created in hydraulic actuators. Exceeding the design pressure limits caused damage to the bolt holes of the cap piece actuator. The pressure in the sub-piston space of the hydraulic prop was also analysed. The previous research conducted on mechanically powered roof supports focused mainly on bench tests. The results of the analysis carried out under real testing conditions currently comprise the starting point for the development of a new method to reduce adverse effects. Under the mining and geological conditions where the research was carried out, a high load on the roof’s side was under the load applied directly on the powered roof support. The load of the test’s results identified problems related to the safety valve in the sub-piston space of the actuators as it did not reach its opening time during the build up of the load.