Investigation of the Effects of Weak Floor Conditions on the Stability of Coal Pillars

摘要

Failure of a mine floor supporting coal pillars frequently occurs when the subcoal strata include 'underclays' or other low-strength strata. The failure process has been studied to define the response of these materials to applied coal pillar loads and to determine the applicability of bearing capacity analysis to evaluate unsafe conditions. An investigation was conducted of both the intact and in-situ geotechnical properties of the subcoal strata and the installation of floor movement monitoring instrumentation. The results of these studies indicated that both the shear strength of the underclay and the stratigraphy of the subcoal strata must be considered in the analysis. The shear strength was the major controlling factor determining the ultimate load-carrying ability of the materials, but the thickness and stratigraphic position of the weak layers influenced the mechanism of the failure process.