Estudio de las características geomecánicas del macizo rocoso en la construcción del túnel Papallacta del proyecto hidroeléctroco Quijos

Abstract

The current research proposes to determine the significant geometric characteristics in the drilling area of Papallacta Tunnel to install the adequate tunnel support and guarantee the stability of the tunnel. Quijos Hydroelectric project is located between Cuyuja and Baeza parishes, Quijos County, Napo province, this project was carried out with the use of maps, geologist compass, geological hammer, measuring tape and mapping sheets. It also used the bibliographic map research, exploratory probing, geomechanical laboratory tests, as well as all the previous studies carried out. These were complemented with the field trip research which was carried out through the analysis of parameters such as: unconfined compressive strength, RQD, separation, persistence, roughness, slit, filler material, weathering, humidity, orientation of structures, lithological changes. As a result, six types of lithologies were determined, they were: alluvial, basaltic lava, paleoslope deposit, paleochannel, volcanic dross and schists. According to the geological and geotechnical classification theories with the use of RMR Bieniawski and Barton Q index, it was possible to obtain the following values: Rock mass 10 m. type I quality, 1167.35 m. type II quality, 745.60 m. type III quality, 472.07 m. type IV quality, and 499.25 m. type V quality. The tunnel drilling is manual and conventional. The support regarding to IV and V quality must be placed as soon as possible to avoid the deformation of the section due to the lessening of the blocks of the tunnel collapse. The amount of support to be installed is up to the rock mass quality which will be used to stabilize the rock mass, guarantying the safety of both, people and machinery in the area.