Forensic analysis of hydraulic props in longwall workings

Abstract Forensic mining engineering tackles the application of mining engineering principles and methodologies to determine the causes of deficient performance in a given excavation or support, elaborating conclusions in the shape of expert opinions. Study of real cases, as well as development of campaigns for in-mine measurement and instrumentation, constitutes an element of unquestionable interest for forensic engineers. For that reason, the present work studies support in several coalmines in which the longwall exploitation method is employed through hydraulic-prop control. A methodology—based on prop-pressure measurement—is defined to analyse support in longwall workings. Subsequently, equipment designed for in situ measurement of roofwall pressures on support is put forward. Such measurements have been undertaken in a total number of twelve workings located in the coal basin of Castile-Leon (northern Spain). A detailed description of two of these workings is undertaken (Seam 24 and Seam Ancha), where pressure measurements were simultaneously performed in several prop rows and analysed according to the working’s exploitation stages. Prop behaviour is also analysed when undertaking in-mine blasting labours or whenever specific prop failures take place. Average values of support pressure obtained for the mines studied are indicated as conclusions.