Effect of Niche-Tunnel Face Distance and Excavation Time in Tunnel Construction

Abstract

Estimated time and costs of construction are one of the most important factors influencing the decision whether and how a tunnel is to be built. Underground excavation works carry a lot of uncertainties that effect the time and cost of tunnel construction so it is essential to make the decisions based on the past best experiences. This study has analyzed the time needed to load the muck in truck, measured in 89 tunnel faces which have different distance from tunnel face to nearest niche, measurements are done in excavation phase of 10.245,00 meters of tunnels which have different diameters varying from 4,20 to 9,40 m. Results indicate that the best distance between tunnel face and niche increase linearly the time of excavation from 0 to 200 meters and exponentially for distances longer than 200 m. It is concluded that in small and medium diameter tunnels the optimal excavation time is achieved when distance from niche and tunnel face is not longer than 200 meters.