Liquefaction potential of paste fill at Neves Corvo mine, Portugal

AbstractA trial stope was used at Neves Corvo mine, Portugal, to help to establish the minimum cement content required to avoid liquefaction of the mine's paste fill. About 40 m of paste fill at cement contents varying from 0.5 to 5% was placed in the stope. When the paste had cured an investigation comprising cone penetration tests (CPT), drilling and sampling of the paste and laboratory testing was carried out. The emphasis of the study was on the density of the paste and the effect of cement content on its properties. For the study of liquefaction density is best quantified by the state parameter, which measures how far the current state of a material is from the steady state or the ultimate state that a soil will reach when sheared to large strains. The in-situ state was evaluated by methods based on CPT, density measurements and laboratory triaxial tests on 'undisturbed' samples. The CPT results gave a direct measure of state and were found to be the most reliable of the methods used.The main conclus...