Mining Publication: Longwall Shield and Standing Gateroad Support Designs - Is Bigger Better?

Roof support systems, longwall shields in particular, have persistently grown in size and capacity for the past 25 years. Why is this? Is it a good thing or is it unnecessary? What are the consequences of this bigger-the-better design philosophy? Rarely do we see a one size fits all approach to roof support except when it comes to longwall shields, where the historical trend for new procurements is to simply purchase the highest capacity support you can buy. Does high capacity ensure failures will not occur? The answer is no! The highest capacity tailgate supports are typically the ones that fail the most often. What does this tell us? It tells us that there are fundamental aspects of support design and ground control that we still do not understand or recognize when designing a support system. This paper provides an interesting evaluation of these issues and proposes a different approach to support design that attempts to match the support performance characteristics to the ground behavior. Along the way, some of the old premises of support design will be discarded, and new controversial ideas developed. Thinking outside the box never hurt any industry. Mining has made it a common practice.