... than 80 m long. It can be seen, from these photographs, that, even enclosed yieldable steel set in 500mm center was employed an ultimate roadway collapse was unavoidably incurred as a consequence of either floor heave, roof lowering or wall convexity. This phenomenon implies that the stress state...

... on the approach defined by Kovari et al. (1988). At that, the influence of desaturation on activation of the swelling rock potential was taken into account. The proposed curve is nonlinear on a semilogarithmic scale which emphasizes even more the observed phenomenon that a small allowed floor heave significantly...

... The characteristics of the floor Strata and how they react to external factors (such as increases in water content and applied stress)usually are not include in the mine design process. Floor heave has long been a nagging if not critical problem-- not only in coal mines, but also in uranium mines, tunnels and other...

... of the plastic deformation and the tensile fracturing of elements around the 4th crosscut are shown in Fig.4. In Fig.5, the deformation of the crosscuts and in Fig.6, the amount of the floor heave are illustrated. All these figures are obtained at the stage when the secondary rock stress (P=2 kg/cm2) was ap...

... the floor and the stress redistribution in the rock due to the excavation of the open- ing (Terzaghi 1925). The relief of the iso- tropic stress component results in the per- colation of water into the affected zone from distant parts of the rock mass,so that floor heave is still to be expected if the entry...

... Reservoir Characterization metals & mining Engineering Upstream Oil & Gas tension crack Rock mechanics reservoir geomechanics geotechnical consultant floor heave foundation shaft geotechnical study weak rock construction deformation multi-discipline approach evaluation...

... shaft, the rate ?f floor heave attained as much as 15cm/day JUSt after the area absorbed sufficient amount of water due to the similar accident ~entioned above. It is clear that increase ~n moisture in the rock mass causes severe SlYelling. Stress increase due to mining operations is another unfavorable...