Underground » Strata Control and Windblasts
Previous projects C22008 and C24015 funded the development of a roof support design approach that takes account of differing roof conditions, effect of support type and stiffness that can be used for mine design and in the strata management process.
In this project an analytical framework was developed for roadway stability that provides a measure of both support load and roof convergence which can be matched and updated against roof monitoring data. The developed Roof Beam Support Analysis (RBSA) program is based on beam-column principles and incorporates bending, immediate roof failure and shear. The approach relies upon inputs from the Geophysical Strata Rating (GSR), roof bolt characteristics including pull-out stiffness/load, in-situ stress ratio and unconfined compressive strength (UCS).
It has been used to investigate the impact of varying stress conditions and different support types for both roadways and intersections via comparison with monitoring data at several Australian underground coal mines. Using this model, estimates of roof convergence for various heights of softening (or surcharge loading) above a roadway can be obtained for a given support pressure and plotted on a curve, i.e., ground response curves. A unique set of ground response curves can be derived for any support configuration, stress conditions and strata characteristics.
Outcomes from this project include the User Guide including installation instructions for the RBSA program and examples.