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Abstract

Many tunnels in Costa Rica have been excavated through volcanic lithology and a large portion of them excavated through volcanoclastic breccias. These breccias form continuous and isotropic masses without fractures that limit the application of common systems of rocks classification based on information of fractured media. The engineering design of these works needs investigations and the establishment of methods for characterization and evaluation of this kind of material. The rock analyzed in this study corresponds to breccias found through Tertiary volcanic geology of the Doán Formation in Costa Rica. The strength properties were determined by means of laboratory and in situ tests. RMi criterion for massive rocks was adopted as a tentative to describe the tunnel behavior in these materials. Finally, comparisons and discussions about the observed tunnel behavior with the predictions by RMi criterion are presented.

Limitaciones de la previsibilidad del comportamiento de túneles en macizos de brechas volcanoclásticas

Keywords:
Reservoir Characterization, massive breccia, xv colombian geotechnical congress, machine learning, Upstream Oil & Gas, Palmström, Artificial Intelligence, strength, massive rock, structural geology
Subjects:
Reservoir Characterization, Exploration, development, structural geology
Resumen

Muchos de los túneles en Costa Rica fueron excavados a través de litologías volcánicas y la mayor parte de ellos en brechas volcanoclásticas. Esas brechas forman materiales continuos e isotrópicos sin fracturas que limitan la aplicación de sistemas de clasificación geomecánica, los cuales fueron establecidos para medios fracturados. Los proyectos de esas obras necesitan de investigaciones y la definición de metodologías para la caracterización de estos materiales. La roca analizada en este estudio corresponde a las brechas encontradas en macizos volcánicos terciarios de la formación Doán de Costa Rica. Las propiedades de resistencia fueron determinadas a partir de ensayos de laboratorio y campo. El criterio RMi aplicable a rocas masivas fue implementados como una tentativa para describir el comportamiento del túnel en estos materiales. Finalmente, hay una comparación y discusión sobre el comportamiento observado durante la excavación con las previsiones obtenidas a partir del criterio RMi.

Palavras chaves: Brecha volcaniclástica, rocas masivas, rocas blandas, túnel, efecto escala.

Keywords:
Reservoir Characterization, massive breccia, xv colombian geotechnical congress, machine learning, Upstream Oil & Gas, Palmström, Artificial Intelligence, strength, massive rock, structural geology
Subjects:
Reservoir Characterization, Exploration, development, structural geology
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2016. Sociedad Colombiana de Geotecnia. Permission to distribute - International Society for Rock Mechanics
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