A holistic examination of the geotechnical design of longwall shields and associated mining risks

摘要: This paper examines the design of longwall shields, focusing on those geotechnical aspects that are critical to either their success or failure during extraction. The driver for is recognition in many instances, shields assessed and designed along similar lines roadway ground support systems, namely according typical normal conditions. However will contend this inappropriate as unlike cannot be supplemented with additional secondary localised areas adverse In other words, shield needs what judged worst case conditions, outcome being a well-designed significantly over-rated majority its working life. it argued capital cost such can readily justified prudent risk-based essential minimising future business risks due strata instability face. Shield geometry discussed including relevant factors leg angle, inclination top caving shield, canopy ratio, operating height range tip face distance, these all well established considerations most importantly, whereby inadequate render highly ineffective. issue distance considered detail, particular extent by which an important consideration. importance maximising set yield ratio within practical limits discussed. Overall aim provide industry suggested guidelines use when designing hopefully initiate discussion subject not covered entirety published technical literature.