Assessment of dynamic loading and rapid yield valve requirement for powered roof supports in longwall workings

Abstract

Longwall working under difficult to cave strata condition are prone to en masse caving of strata during periods of major roof weighting. The major concern for support selection, to ensure safe working under such strata condition, should be to design the face supports to sustain the dynamic loading resulting due to en masse caving. Merely increasing the capacity of support may not be useful for safe working under such strata conditions. This paper describes an approach to assess the dynamic load and estimation of the various selection parameters of rapid yield valve such as the minimum and the peak discharge rate and the response time. This can be useful as a tool to ensure safe working of the rational capacity powered roof support by safe release of dynamic loading energy under the given loading condition.