Reardon, D 2026, 'Evolution of parabolic arch design rationale for intersection support and variations between sites', in D Cumming-Potvin & J Wesseloo (eds), Ground Support 2026: Proceedings of the 11th International Conference on Ground Support in Mining, Australian Centre for Geomechanics, Perth, pp. 1-14, https://doi.org/10.36487/ACG_repo/2625_28
(https://papers.acg.uwa.edu.au/p/2625_28_Reardon/)
Abstract: Cable bolting is commonly used in most underground mines in Australia to support large spans and intersections. The assessment methodology currently employed by many mines adopts a ‘parabolic arch’ design rationale to support a tension arch of estimated volume with known rock mass density. Once the weight is determined, a number of cables are applied to the span. These are typically evenly-spaced and include allowance for a Factor of Safety. 
During routine review work, the author has observed 6 differing versions of intersection support design rationale including 4 different versions of ‘parabolic arch’ design across mine sites in Australia. Calculations across multiple mine sites vary for cable bolt capacity, rock mass density selection, measuring of intersection span, cable bolt spacing, and tension arch depth to span ratio. Each assessment method observed has varying advantages and disadvantages for different ground conditions, excavation geometry, structural settings, rock mass properties and stress regimes. 
This paper aims to collate and contrast the methods for intersection design – which are currently employed by multiple sites – to offer junior engineers a point of reference for intersection support. It is hoped that rather than copying and pasting the same intersection cable bolting design spreadsheet across operations, engineers may pick and choose between different design approaches based on the most relevant failure mode and ground conditions observed at each mine.
Other observations are noted regarding current trends in cable bolting installation, QA/QC testing, plate and tensioning, smart cable installation, intersection excavation sequence, closure pillar intersection management and historical failures.

Keywords: intersection, cable bolting, parabolic arch