Análisis geológico-estructural con el sistema hidrogeológico de túnel en construcción, Ollachea, provincia de Carabaya, Perú
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Fecha
2022
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es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
El túnel Ollachea forma parte de la carretera Interoceánica Sur, ubicada en la ciudad de
Ollachea, Provincia de Carabaya, en Perú, y se caracteriza por su contexto hidrogeológico,
encontrándose aguas subterráneas termales de altas temperaturas, alcanzando los 80°C. Es
por ello que, en este trabajo, se establece una relación entre las unidades geológicas y
discontinuidades con el sistema hidrogeológico, analizando, además, las permeabilidades
del macizo rocoso con el fin de identificar los sectores más críticos.
Con esto, se reconoce que la litología a nivel túnel consta de depósitos coluviales, siendo
los más recientes vinculados a acuífero, y los más antiguos a acuícludo y acuitardo;
andesitas y cuarcitas, comportadas como acuíferos; areniscas, vinculadas a acuitardo; y
pizarras, a acuícludo. Estructuralmente, se hayan diaclasas y fallas, de orientación Norte Sur al inicio y centro del túnel, y Noreste-Suroeste al final de él. Además, se reconocen 6
tipos de rellenos en las discontinuidades, carbonato, óxido de hierro, arcilla, limolita,
cuarzo y yeso. Con respecto al análisis de infiltración del túnel, se encuentran ingresos de
caudales provenientes del sistema hidrotermal y/o aguas meteóricas que van desde los 30°C
hasta los 80°C, siendo mayor en la zona central del túnel. Las permeabilidades, calculadas
con el método Garshol (2013), indican gran variedad de valores, siendo los mayores en la
zona centro y la final del túnel.
Con lo descrito anteriormente, se reconocen 2 sectores críticos, el primero ubicado en el
centro y el segundo en la salida del túnel, caracterizados por poseer temperaturas mayores a
los 60°C y por sus características geológicas estructurales e hidrogeológicas. El primero
corresponde a andesitas de la Unidad Volcánica con comportamiento de acuífero, con clase
de roca tipo II-III, discontinuidades de orientación NW-SE, NNE-SSW y W-E rellenas de
carbonato y arcilla.
El segundo sector crítico pertenece a la Formación Sandia, compuesta por cuarcitas y con
comportamiento de acuífero. Tiene una roca de clase tipo V-VI y se compone de diaclasas
y fallas orientadas NNW-SSE preferentemente, rellenadas por arcilla y limolita. Ambos
sectores, presentan una permeabilidad suficiente del macizo rocoso para facilitar, junto con
las características anteriores, la infiltración de agua en la zona, haciéndolas propensas a
sufrir riesgos en la sociedad.
The Ollachea Tunnel is part of the South Interoceanic Highway, located in the city of Ollachea, Carabaya Province, Peru, and is characterized by its hydrogeological context, finding underground hot springs with high temperatures, reaching 80°C. That is why this work establishes a relationship between geological units and discontinuities with the hydrogeological system, also analyzing the permeability of the rock mass in order to identify the most critical sectors. Thus, it is recognized that the lithology at the tunnel level is made up of colluvial deposits, being the most recent ones those linked to aquifers and the oldest aquicludes and aquitards; andesites and quartzites behaved like water carriers; sandstones, connected to the aquitard; and slates, accumulated. Structurally, there are slopes and unevenness, North-South orientation at the beginning and center of the tunnel, and North-Southwest at the end of it. In addition, 6 types of charges are recognized in discontinuities: carbonate, iron oxide, clay, siltstone, quartz and gypsum. Regarding the analysis of the infiltration of the tunnel, there are inflows of flows from the hydrothermal system and/or meteoric waters that oscillate between 30°C and 80°C, being higher in the central zone of the tunnel. The permeabilities, calculated with the Garshol (2013) method, indicate a wide variety of values, being the highest in the central zone and at the end of the tunnel. As previously described, 2 critical sectors are recognized, the first located in the center and the second at the exit of the tunnel, characterized by temperatures above 60°C and by its geological, structural and hydrogeological characteristics. The first corresponds to andesites of the Volcanic Unit with aquifer behavior, with discontinuities of rocky orientation of classes II-III, NW-SE, NNE-SSW and W-E filled with carbonate and clay. The second critical sector belongs to the Sandia Formation, composed of quartz and aquifer behavior. It presents type V-VI rock and is composed of joints and falls with a NNO-SSE orientation, preferably filled with clay and limestone. Both sectors present a permeability of the rock mass sufficient to facilitate, together with the previous characteristics, the infiltration of water in the area, making them prone to risks in society.
The Ollachea Tunnel is part of the South Interoceanic Highway, located in the city of Ollachea, Carabaya Province, Peru, and is characterized by its hydrogeological context, finding underground hot springs with high temperatures, reaching 80°C. That is why this work establishes a relationship between geological units and discontinuities with the hydrogeological system, also analyzing the permeability of the rock mass in order to identify the most critical sectors. Thus, it is recognized that the lithology at the tunnel level is made up of colluvial deposits, being the most recent ones those linked to aquifers and the oldest aquicludes and aquitards; andesites and quartzites behaved like water carriers; sandstones, connected to the aquitard; and slates, accumulated. Structurally, there are slopes and unevenness, North-South orientation at the beginning and center of the tunnel, and North-Southwest at the end of it. In addition, 6 types of charges are recognized in discontinuities: carbonate, iron oxide, clay, siltstone, quartz and gypsum. Regarding the analysis of the infiltration of the tunnel, there are inflows of flows from the hydrothermal system and/or meteoric waters that oscillate between 30°C and 80°C, being higher in the central zone of the tunnel. The permeabilities, calculated with the Garshol (2013) method, indicate a wide variety of values, being the highest in the central zone and at the end of the tunnel. As previously described, 2 critical sectors are recognized, the first located in the center and the second at the exit of the tunnel, characterized by temperatures above 60°C and by its geological, structural and hydrogeological characteristics. The first corresponds to andesites of the Volcanic Unit with aquifer behavior, with discontinuities of rocky orientation of classes II-III, NW-SE, NNE-SSW and W-E filled with carbonate and clay. The second critical sector belongs to the Sandia Formation, composed of quartz and aquifer behavior. It presents type V-VI rock and is composed of joints and falls with a NNO-SSE orientation, preferably filled with clay and limestone. Both sectors present a permeability of the rock mass sufficient to facilitate, together with the previous characteristics, the infiltration of water in the area, making them prone to risks in society.
Notas
Tesis (Geólogo)
Palabras clave
Geología, Hidrogeología, Construcción de Túneles, Perú, Ollachea