TY - THES

T1 - Geotechnical characterization of the rock mass surrounding the Aljustrel mining compound

AU - Goncalves Nunes Rodrigues, Tiago Manuel

N1 - no embargo

PY - 2022

Y1 - 2022

N2 - In an underground production environment, the most evident impact from rock blasting activities are ground vibrations. In mining operations near urban areas disturbance and complaints on behalf of populations are not uncommon. This document studies the ground surface geotechnical properties of the Aljustrel town (Alentejo province, Portugal). To achieve the objectives of this study, a database is considered compiling information relative to 2.175 vibration records measured at ten structures within different sections of Aljustrel between 2018 and 2022. These served as a basis to estimate, by means of multiple linear regression, 23 valid characteristic attenuation equations according to the mathematical expression presented by Johnson (1971). Such equations consider categorical variables like the existence of a rock mass discontinuity created by an initial production blast; section of the Aljustrel town where the records were monitored; geographical orientation between the blasting and the monitoring points; initiation pattern geometry; and time delay between adjacent holes. Results suggest that for reduced distances, the inexistence of a rock mass discontinuity directly above the blasted volume and the north-south direction influence the propagation of seismic waves released by the explosive charges, being that smaller maximum charges per delay are recommended in these situations. For great distance values, a spiral initiation geometry contributes to the measurement of greater vibration amplitudes. A detailed study considering four structures, where the respective building materials� waves propagation velocity and geometrical parameters are measured, indicates that no significant vibration amplification caused by resonance has occurred for events registered at these locations.

AB - In an underground production environment, the most evident impact from rock blasting activities are ground vibrations. In mining operations near urban areas disturbance and complaints on behalf of populations are not uncommon. This document studies the ground surface geotechnical properties of the Aljustrel town (Alentejo province, Portugal). To achieve the objectives of this study, a database is considered compiling information relative to 2.175 vibration records measured at ten structures within different sections of Aljustrel between 2018 and 2022. These served as a basis to estimate, by means of multiple linear regression, 23 valid characteristic attenuation equations according to the mathematical expression presented by Johnson (1971). Such equations consider categorical variables like the existence of a rock mass discontinuity created by an initial production blast; section of the Aljustrel town where the records were monitored; geographical orientation between the blasting and the monitoring points; initiation pattern geometry; and time delay between adjacent holes. Results suggest that for reduced distances, the inexistence of a rock mass discontinuity directly above the blasted volume and the north-south direction influence the propagation of seismic waves released by the explosive charges, being that smaller maximum charges per delay are recommended in these situations. For great distance values, a spiral initiation geometry contributes to the measurement of greater vibration amplitudes. A detailed study considering four structures, where the respective building materials� waves propagation velocity and geometrical parameters are measured, indicates that no significant vibration amplification caused by resonance has occurred for events registered at these locations.

KW - Bodenvibration

KW - Vorhersagemodelle

KW - Eigenfrequenz

KW - Produktionssprengung unter Tage

KW - Bergbaukomplex Aljustrel

KW - Ground vibration

KW - Prediction models

KW - Natural frequency

KW - Underground production blasting

KW - Aljustrel mining compound

U2 - 10.34901/mul.pub.2023.85

DO - 10.34901/mul.pub.2023.85

M3 - Master's Thesis

ER -