The paper describes a case study of the safety hydraulic system damage in the working of a longwall in a Polish coal mine. The safety elements are a component of the powered roof supports which secure the shield against damage during rock burst incidents. The damage event, which occurred in the hydraulic system during the mining process, caused the uncontrolled lowering of the powered roof support height during the mining process. The uncontrolled lowering of a shield may cause the danger of the loss of the stability along the longwall working in the form of a rock burst and collapses and may represent a serious and immediate danger to the safety and health of employees. Based on the results of the computational fluid dynamics methods (CFD) analysis of the safety elements in the hydraulic system of longwall 2-leg shield, the causes of damage were diagnosed and presented. The CFD and the strength analysis by the finite element method (FEM) were used for numerical modeling. The diagrams and maps of changes of parameters having an impact on the damage mechanism in safety elements of the hydraulic leg were developed based on the results of model tests. The forecasted values of stress distributions in the safety system of the hydraulic leg have made it possible to identify the reasons of the damage causes, verified by real observations.
The article discusses a case of security hazard in a longwall equipped with a properly selected chock shield support with two legs, technically efficient, introduced to the market and for operation in compliance with the requirements covering Polish hard coal mining. As a cause of the hazard an accidental coincidence was indicated, such as the occurrence of a tremor at an area with unfavourable geometry for the operation of the support section and leg (including the shift of the double-telescopic leg from the 1st to the 2nd hydraulic stage) at the time of the mining process. Immediate safety measures were applied successfully. They were aimed at minimizing the conditions dangerous to the crew. The section was withdrawn and spragged again. As a result, the leg operated in full extension mode of the 1st hydraulic stage, obtaining the required strength and geometry of the section and leg. The presented case study will be additionally supplemented in the future with selected analytical and bench tests.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.