Document Type

Conference Paper

Publication Date


Publication Details

This conference paper was originally published as Trueman, R, Callan, M, Thomas, R and Hoyer, D, Quantifying the impact of cover depth and panel width on longwall shield-strata interactions, in Aziz, N (ed), 10th Underground Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 2010, 97-107.


Results of a series of back-analyses of the interaction between longwall shields and strata at a number of mines are presented. The purpose of these back-analyses was to quantify the impact of cover depth and panel width on shield performance. Recently developed shield load cycle analysis theories were used to quantify the interaction between shields and strata. A load cycle is the change in support pressure with time from the initial setting of the shield against the roof until the subsequent release and movement of the support, which typically corresponds to a single shear. Historical shield pressure data from five longwall mines in Australia and Europe were back-analysed, together with strata delay data for the longwall faces. An assessment of the geology of the near-seam overburden was also made for each site. The longwall panels incorporated cover depths ranging from 50 to 770 m and panel widths ranging between 168 to 319m. Use was made of a modified version of the longwall visual analysis (LVA) software that was specifically extended for this project and provided maps of the critical load cycle parameters implicit to the utilised analysis methodology. The major extension of the software involved presenting the outputs on the basis of individual load cycles for every shield as opposed to a time or chainage basis, thus allowing load cycle analysis to be carried out. In total about 6.5 km of longwall retreat and over 2 000 000 individual load cycles were back-analysed. Together with the strata delay and geological data, this enabled the effects of panel width and cover depth to be quantified within the range of the data.