A New Roof Strata Cavability Index (RSCi) for Longwall Mining Incorporating New Rating System

Abstract

This paper presents a new index to assess caving potential of roof strata above longwall panels. Nine inherent parameters were chosen as significant affecting factors in three categories, including roof strata characteristics, roof discontinuities properties and local features. Fuzzy hybrid multi criteria decision making was used by combining fuzzy analytic network process technique and fuzzy decision making trial and evaluation laboratory method to develop a new rating system. Subsequently, roof strata cavability index (RSCi) was defined as a simple summation of ratings for all parameters, indicating the cavability level qualitatively. The RSCi was applied to determine the cavability of various actual cases of worldwide longwall panels. In addition, the correlation between RSCi and span of main caving was examined where reliable performance of the new index was noted. It was concluded that RSCi is a simple and efficient tool to assess the cavability of immediate roof and evaluation of caving intervals in longwall mining.