Thesis EVALUACIÓN DEL DESEMPEÑO DEL INDICADOR SÍSMICO CALOR LIBERADO
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Date
2021-09
Authors
MARTINOLI SANTOS, ANDRÉS
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Abstract
El manejo de la sismicidad inducida por la actividad minera extractiva es uno de los mayores problemas que enfrenta la minería. Si bien, es un problema documentado en países de gran tradición minera (Estados Unidos, Canadá, Australia y Chile) durante más de un siglo, este se ha acentuado con el tiempo debido a las profundidades que ha alcanzado la extracción mineral y, por ende, al trabajo directo sobre roca primaria. Los niveles de esfuerzos y tensiones involucrados influyen en un aumento de la posibilidad de ocurrencia de estallidos de roca y eventos sísmicos al interior de la mina provocando importantes pérdidas de vidas humanas e infraestructura. Para enfrentar este problema se han puesto en práctica diversas medidas. Una de ellas es la implementación de indicadores sísmicos que permiten, mediante el estudio de distintos parámetros, identificar periodos en los que es más probable que ocurran eventos sísmicos de magnitudes significativas. El objetivo de este trabajo es relacionar la influencia del calor liberado, generado por la microsismicidad en la mina, con la ocurrencia de eventos sísmicos en la mina y de esta forma determinar los parámetros que permitan el mejor desempeño del indicador calor liberado. Utilizando una base de datos de sismicidad registrada en la mina Bobrek durante un periodo de 15 meses se aplicaron dos metodologías distintas: calor emitido acumulado y bandas de alerta. Mediante estas se encontraron parámetros bajo los cuales el indicador mostró un desempeño óptimo, determinado por la maximización del PSS, identificando periodos de alerta por riesgo sísmico. Se concluyó que la metodología del calor liberado acumulado crítico se desempeñó en mejor forma que la metodología de bandas de alerta. Además, los parámetros óptimos para el funcionamiento del indicador corresponden a un calor liberado acumulado crítico Q*+=8.75 [GJ], con un intervalo T de 24 horas y una magnitud crítica Mw*= 1.5.
The effects of the induced seismicity caused by mining activities are one of the biggest problems that the mining industry faces. Although it has been documented by countries with a great mining tradition (United States, Canada, Australia and Chile) for over a century, the problem has been intensified throughout the years due to the greater depths that mineral extraction reaches, and thereby, to the work on primary rock. The stress levels and tensions involved increase the possibility of a rockburst occurrence. Seismic events inside the mine cause important losses of human lives and infrastructure damage. To face this problem several protocols have been implemented. One of those is the implementation of seismicity indicators which allow to identify, through the study of different parameters, periods of time when it is most likely for a seismic event of considerable magnitude to occur. The objective of this work is to connect the influence of the radiated heat, generated by the microseismicity inside the mine, with the occurrence of seismic events and thus determine the parameters that allow the best performance of the radiated heat indicator For certain values of seismic parameters – magnitude, frictional heat and time -, the indicator should show an optimal performance, determined by maximizing the PSS value, identifying alert periods for seismic hazard. To do so, we used two different methodologies: the accumulated radiated heat and the alert strips. It was concluded that the critical accumulated radiated heat methodology performed better than the alert strips methodology. Furthermore, the optimal parameters for the operation of the indicator correspond to critical accumulated radiated heat Q*=8.75 [GJ], with a T interval of 24 hours and critical magnitude Mw*= 1.5.
The effects of the induced seismicity caused by mining activities are one of the biggest problems that the mining industry faces. Although it has been documented by countries with a great mining tradition (United States, Canada, Australia and Chile) for over a century, the problem has been intensified throughout the years due to the greater depths that mineral extraction reaches, and thereby, to the work on primary rock. The stress levels and tensions involved increase the possibility of a rockburst occurrence. Seismic events inside the mine cause important losses of human lives and infrastructure damage. To face this problem several protocols have been implemented. One of those is the implementation of seismicity indicators which allow to identify, through the study of different parameters, periods of time when it is most likely for a seismic event of considerable magnitude to occur. The objective of this work is to connect the influence of the radiated heat, generated by the microseismicity inside the mine, with the occurrence of seismic events and thus determine the parameters that allow the best performance of the radiated heat indicator For certain values of seismic parameters – magnitude, frictional heat and time -, the indicator should show an optimal performance, determined by maximizing the PSS value, identifying alert periods for seismic hazard. To do so, we used two different methodologies: the accumulated radiated heat and the alert strips. It was concluded that the critical accumulated radiated heat methodology performed better than the alert strips methodology. Furthermore, the optimal parameters for the operation of the indicator correspond to critical accumulated radiated heat Q*=8.75 [GJ], with a T interval of 24 hours and critical magnitude Mw*= 1.5.
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Keywords
SISMICIDAD INDUCIDA , EXPLOSIVOS EN ROCAS , SISMOLOGÍA