The Geological Survey by Horizontal Borings for Explorating ahead of the Tunnel Face and the Successful Fitness with the Actual Results in the Seikan Undersea Tunnel Works

Abstract

Since the start of the Seikan Undersea Tunnel construction, long horizontal exploratory borings have been employed in order to forecast geological conditions ahead of tunnel face.
This article describes how the geological charts were produced beforehand from the accumulateddata of the advanced borings, and the comparisons are made with the factual geological maps obtained at the excavation site.
This paper also presents the evaluation method for estimating of the rock condition and the water inflow.