Abstract:

Value engineering is applied to evaluate the two construction methods, i.e., twintube pipe jacking method and singletube shield tunneling method, for a bulk power transmission tunnel to connect two power distribution substations. Power cable connection function and environmental impact due to construction, cooling system for power transmission, easy for cable installation, convenient for different stage cable installation, construction flexibility, building protection during tunneling, schedule and cost of the two methods are evaluated for the two construction methods respectively in this paper. Singletube shield tunnel method is selected as the proper tunneling method for this project. Larger size bolt is used to reduce the intervals between the bolt holes and to increase the precision of segment erection; therefore, sharp curve tunnel is successfully applied without entering into the existing adjacent buildings. For the encountered huge size cobbles and compact gravel beneath the ground water table, the shield machine cutter head is fully replaced.

Key words: power transmission tunnel, value engineering, pipe jacking, shield tunnel, curve tunnel, sharp curved shield tunnel, segment erection precision, cobble/gravel stratum, shaft