Geostatistical modelling of pore pressure data: An application to Smart Markers (ENSM) in Open-Pit Mining

Abstract

scription Edit For the mining industry, it is essential to know the distribution of the pore pressures exerted by the groundwater in the walls of the pit, which depends on the hydrogeological characteristics of the rock and the excavations. An inadequate management of pore pressures in open-pit mining can obstruct access to operating areas, increase the use of explosives and increase their failure, generate acid drainage and geotechnical instability in the pit itself. However, in mining practice pore pressure measurements are scarce. In order to overcome this limitation, intelligent markers (Enhanced Networked Smart Markers-ENSM) have been developed, which have pore pressure and deformation sensors coupled to pit drillings in depths of up to 200m. This network of intelligent sensors (ENSM) could provide a wealth of data never before recorded in open-pit mining operations, which allows knowing more accurately the hydrogeological conditions and anticipate the dynamics of pit deformation. In the present contribution, we propose a strategy to model the spatial continuity of the regionalized data set that will capture the intelligent markers, through a variographic analysis, to then predict the pore pressure in space and represent the variability in all spatial scales. The methodological approach proposed allows understanding how the rocks and the water contained, respond to changes in the tensional state and the hydraulic pressure regime originated by mining operations. Moreover, the proposed approach identifies the spatial variability of pore pressures and the existence of heterogeneities and allow to achieve better coupled geotechnical models. However, in a system strongly controlled by geological structures where the flow of water in the hydrogeological units can be diverted and the measurement depends on the direction of sampling, its implementation is limited and requires extensive theoretical development, considering two dimensions for the cross space i.e., the azimuth and the inclination additionally to the three conventional coordinates (north, east and elevation).