The shape effect and rock mass structural control for mine pillar design

摘要

The shape effect, widely studied by researchers as Hustrulid (1973), Protodyakonov (1964),rnObert and Duvall (1967) and Bieniawski (1984), has had its importance recognized in the scientific and technicalrncommunity since a long time ago (Bunting apud Hustrulid, 1973; Bunting, 1911). In all its technicalrnapplications however, the rock mass structure has not been taken into account. But as Bell (2000) also stresses,rnit is of fundamental importance for the determination of compressive strength in rock masses. This study aimedrnto investigate the variability of the results obtained in uniaxial compressive stress tests, using prismatic andrncylindrical specimens, considering their slenderness (respectively L/H and D/H), which Bieniawski (1984a,b)rndefines as the relationship between the smaller size of the section and its height. In order to quantify the influencernof the rock mass structure on the result of the shape effect expression, one intended to correlate its parametersrnwith the value of Q-system of Barton (2007).