Investigation of the excavatability properties of the rock masses along the T3 tunnel (Pehlivantaşi-Rize)

In this study, the excavatability properties of the rock masses along the T3 tunnel (Pehlivantaşı-Rize) alignment were investigated. The engineering geological studies were carried out in three stages as field investigation, laboratory and analyses studies. In order to determine the quantitative descriptions of the discontinuities in rock masses considering the ISRM suggested method, the borehole studies and scanline-surveys were utilized. Laboratory studies were carried out in order to determine the physico-mechanical properties of the intact rocks. In evaluation stage, the rock masses were classified according to the GSI system using the data obtained from field and laboratory studies. Finally, the rock masses were classified according to the excavatability classification systems suggested by Pettifer and Fookes and Tsiambaos and Saroglou, and excavatability characteristics were defined. According to classification of Pettifer and Fookes, the rock masses are hard diggable and easy rippable; diggable and rippable according to Tsiambaos and Saroglou. It was concluded that both methods are compatible with each other. If these results take into account, it is suitable using the hydraulic breaker in ripping process and face shovel in digging process. However, because high daily excavation rate is required in underground excavations, it is suggested to use controlled blasting instead of hydraulic breaker.